Rationale

In Europe, pediatric intensive care followed shortly after the poliomyelitis epidemic in Denmark in 1952. In 1955, Dr. Goran Haglund, a pediatric anesthesiologist, established the first medical-surgical pediatric intensive care unit (PICU) for infants and children at the Children’s Hospital in Göteborg in Sweden.

In France, in 1963, a newborn presented with tetanus and was admitted to l’Hôpital des Enfants Malades of Paris. Shortly afterward, Dr. Gilbert Huault and J.B. Joly, both neonatologists, opened the first multidisciplinary PICU in France at Saint Vincent de Paul Children’s Hospital. This unit was the first pediatrician-directed PICU in Europe; it soon became a major influence on the development of PICUs.

In the mid-to-late 1970s, as pediatric cardiovascular surgery for more complex lesions in infants was developing, nurses provided postoperative care in designated units. Children with Reye syndrome suddenly appeared, requiring complex multisystem care. In addition, in the 1980s, emergency medical services (EMS) systems began transporting severely injured children to hospitals, where they required rapid assessment and intervention by nurses and physicians and initiation of cardiorespiratory and neurologic support.

• 2.
  

  Of the following, which most profoundly influenced the development of early distinct, geographically separate, multidisciplinary pediatric intensive care units?

  
  
  
  
  • A.
    

    Advanced forms of mechanical ventilation

    
    
  • B.
    

    Federal government finance programs

    
    
  • C.
    

    New therapeutic interventions for oncology patients

    
    
  • D.
    

    Nursing

  
  

Preferred response: D

Rationale

Pediatric critical care medicine (PCCM) developed initially through the efforts of pediatric anesthesiologists, as well as pediatric general and cardiac surgeons, and neonatologists. In fact, most of the original PICUs were founded by pediatric anesthesiologists. Before discrete, geographically separate, intensive care units evolved, critically ill children often received close monitoring, intensive nursing care, and pulmonary support in the postanesthetic recovery room.

Rationale

Avedis Donabedian, an early “systems thinker” in healthcare, stated that healthcare quality should be based upon three dimensions: structure-process-outcomes. Structure is the setting in which care is delivered. Process refers specifically to how care is provided, including incorporation of high reliability principles into daily activities. Outcomes refer to endpoints of care, including commonly used quality and safety measures, and other key outcomes such as length of stay, patient/family experience, and cost/value.

• 2.
  

  A care bundle is defined as:

  
  
  
  
  • A.
    

    A flow-chart to guide provider decision making for a disease process

    
    
  • B.
    

    A list of standardized, best practice interventions for a patient population or disease

    
    
  • C.
    

    A way of designing an intensive care unit to cohort patients according to their disease process

    
    
  • D.
    

    Collaboration between multiple hospitals to provide the best possible patient care

  
  

Preferred response: B

Rationale

A care bundle is a relatively short list of standardized, generally evidence-based or best practice interventions for a patient population or disease that, when implemented consistently, leads to improved outcomes. It is the combination of elements performed consistently and in aggregate that drive improvement. A clinical pathway is a flow chart to guide provider decision making.

• 3.
  

  The PICU leadership team at your hospital is discussing the results of a recent analysis of a quality and safety benchmark report showing a drop in performance measures over the previous three quarters. The PICU nursing director states that several PICUs have improved quality by learning from so-called high-reliability organizations. Which of the following industries are commonly cited as high-reliability organizations?

  
  
  
  
  • A.
    

    Coal mining

    
    
  • B.
    

    Commercial aviation

    
    
  • C.
    

    Healthcare

    
    
  • D.
    

    High-speed passenger railroad

  
  

Preferred response: B

Rationale

The most commonly cited examples of high-reliability organizations include U.S. Navy aircraft carrier flight deck operations, commercial aviation, nuclear power, and wilderness/forest firefighting. Whereas many healthcare organizations certainly aspire to become high-reliability organizations, there are few examples (if any) of high-reliability organizations in healthcare today.

• 4.
  

  High-reliability organizations are characterized by five core principles. Which of the following is a core principle of all high-reliability organizations?

  
  
  
  
  • A.
    

    Commitment to resilience

    
    
  • B.
    

    Deference to hierarchy (“command and control”)

    
    
  • C.
    

    Lack of transparency

    
    
  • D.
    

    Preoccupation with success

  
  

Preferred response: A

Rationale

The five core principles of high-reliability organizations include deference to expertise, reluctance to simplify, sensitivity to operations (which often means greater transparency), preoccupation with failure (and learning from failures), and commitment to resilience.

Rationale

All huddles should be led by a designated leader to keep the discussions brief and focused. Mandatory participation of all team members is required for a successful huddle. Huddles should be held in a central location to encourage all team members to attend. Huddles should be incorporated in an institution’s standard work. The duration of huddles should be 10 minutes or less, whenever possible.

• 2.
  

  What is the focus of team training programs?

  
  
  
  
  • A.
    

    Avoiding errors during training to prevent confusion

    
    
  • B.
    

    Developing communication strategies that promote hierarchy among team members

    
    
  • C.
    

    Emphasizing individual tasks, duties, and responsibilities

    
    
  • D.
    

    Facilitated debriefings

  
  

Preferred response: D

Rationale

Team training programs focus on facilitated debriefings to transform experiences into retained knowledge. Members are encouraged to learn all team tasks, duties, and responsibilities. Incorporating errors during training allows for the creation of contingency plans. The focus of communication strategies is to flatten hierarchy and encourage assertiveness. Closed-loop communication maintains a shared mental model among all team members.

Rationale

The charter sets forth a social contract by which professionals justify the privileges of their profession by performing as professionals. It lays out principles that underlie 10 commitments of physicians to patients and society. It is not a description of the good and virtuous doctor. All recognize that doctor by his or her behaviors toward patients and others. It views the social contract in the context of the “medical marketplace” and social and financial pressure. Although it emphasizes altruism and putting the patient first, it goes well beyond that in defining broad commitments to society. The charter recognizes the patient’s right to make informed choices among the available options, but it also lays out commitments under which the physician distributes finite resources equitably and informs patients honestly and as completely as possible so that they can choose wisely.

• 2.
  

  Which is true of the Physician Charter?

  
  
  
  
  • A.
    

    It describes professional responsibilities.

    
    
  • B.
    

    It expresses ethical values.

    
    
  • C.
    

    It mandates professional behaviors.

    
    
  • D.
    

    It sets guidelines for regulatory agencies.

  
  

Preferred response: A

Rationale

The charter describes the responsibilities that fulfill the physician’s professional contract with society. It does not have the force of law and has no power to mandate professional behavior. It does not reduce physician responsibilities to guidelines for actions. It is not so much a statement of ethical values as it is a commitment to 10 practical physician responsibilities.

Rationale

While all five answers are reasonable components of developing a new patient care guideline, only answer C describes an initial planning process that maps out a plan for gaining understanding of the scope of the challenge and for identifying needed participants in the development and implementation of the new guideline. Depending on this preliminary planning work, any of the other four approaches could be needed components of the overall strategy. However, beginning with any of the other four answers could create significant resistance to change (answer A), create significant time-intensive data collection that does not answer targeted questions (answer B), repeat training that does not address the necessary gaps in knowledge (answer D), or fail to recognize the role of other PICU team members in addressing the situation (answer E).

• 2.
  

  You and your team have developed a new patient care guideline for post-op pain management for these patients. The MOST EFFECTIVE and MOST RESPONSIVE means of evaluating the initial impact of these new guidelines is to:

  
  
  
  
  • A.
    

    Develop data collection tools that populate quarterly reports for review.

    
    
  • B.
    

    Track monthly patient satisfaction scores and surveys and review the results with PICU staff.

    
    
  • C.
    

    Perform rapid, real-time data collection for each patient impacted by the new analgesia and solicit verbal feedback on whether or not the patient’s pain has been adequately managed.

    
    
  • D.
    

    Perform rapid, real-time data collection of pre-determined objective and subjective data elements and solicit input from bedside PICU team members for ways to improve the new guideline that can be immediately incorporated and evaluated after ad hoc review by a core team of identified project leaders.

    
    
  • E.
    

    Hold monthly meetings during which the current bedside team caring for any patients undergoing posterior spinal fusions can provide their input on how the guidelines are working.

  
  

Preferred response: D

Rationale

Rapid Plan-Do-Study-Act (PDSA) cycles allow immediate assessment of the impact of change as well as timely and responsive adjustments to new initiatives that address unanticipated consequences of the new guidelines. PDSA cycles evaluate pre-determined outcomes and promote transparency about the effort for all involved PICU team members. In order to avoid premature changes based on single instances, a core leadership team should evaluate proposed changes and adjust planned performance metrics accordingly.

• 3.
  

  Since deployment 6 months ago, these postoperative analgesia management guidelines have been very successful and are being used as a model for interprofessional pain management and team communication among other surgical specialty patients. A senior anesthesiologist who started the pain service and was away on extended sabbatical over the past year returns to clinical service. When first informed, he was skeptical about the guidelines, citing 30 years of personal experience in postoperative pain management as being superior to the approach used in the guidelines. He has cancelled two previously informally scheduled meetings with you to review the new guidelines and discuss his specific concerns. In the past 2 weeks, he has become more vocal in his objections and has voiced his disagreement in front of families in the middle of morning rounds, leading to multiple complaints by PICU team member and family members. You have firsthand experience working with this physician on other successfully implemented patient care initiatives and have always found his brusque comments and opinions to be insightful and well-meaning. You believe that you have a productive, honest, and friendly relationship with him based on your prior shared successes. The BEST initial method for addressing this physician’s disruptive behavior is:

  
  
  
  
  • A.
    

    Meet with the hospital Chief Medical Officer and the department chair of anesthesiology to discuss this individual’s behavior and request that he be removed from participation in clinical care for these patients until he has been counseled and completed education and training on these guidelines.

    
    
  • B.
    

    Meet him in his office with two cups of coffee to begin an impromptu conversation to better understand the basis of his disagreements with the guidelines.

    
    
  • C.
    

    Hold an intervention meeting with the anesthesiologist, yourself, and one or two members of your core guideline development leadership team to acknowledge that the anesthesiologists recent behavior has been disruptive and counterproductive to your shared goals for delivering optimal patient care, to describe the ways in which the guidelines have improved patient care, acknowledge the instances in which the guidelines could still be optimized, and to ask for specific thoughts on how the guidelines can be modified to address his specific concerns and misgivings.

    
    
  • D.
    

    Collect statements from witnesses of his disruptive behavior to share with him and his department chair as examples of the negative impact of his actions, demand that he apologize to the PICU team, and set the expectation that he comply with the analgesia guidelines.

    
    
  • E.
    

    Refer the situation to the hospital professional standards committee.

  
  

Preferred response: C

Rationale

Addressing disruptive behavior directly can be uncomfortable and challenging but is essential in maintaining morale and momentum when leading and implementing change initiatives. Depending on the situation, the specific approach can be preventative and informal (answer B), accusatory (answer D), or punitive (answers A and E). However, in a situation in which the disruptive individual has cancelled previously scheduled meetings, has not commented on the strengths and weaknesses of the guideline, and is interfering with constructive interprofessional team communication and collaboration, a direct confrontation that emphasizes a shared common goal (improving patient care) and outlines unacceptable behavior that still leaves room for education (review of the guideline development process and observed outcomes) and dialogue (specific solicitation of guideline critique) can preserve relationships and avenues for partnership on future projects.

Rationale

The elements of professionalism, namely accountability, respect, and teamwork, need to be consistently present in order for best practice, clinical research, and shared education to occur.

• 2.
  

  Which of the following accurately characterizes gender disparity in the medical workspace?

  
  
  
  
  • A.
    

    About 10% of female physicians have experienced sexual harassment.

    
    
  • B.
    

    A significant gender pay gap persists in medicine.

    
    
  • C.
    

    Male and female physicians are both likely to be introduced as “doctor.”

    
    
  • D.
    

    Women receive similar research start-up funding when compared to men.

  
  

Preferred response: B

Rationale

30% of female physicians have experienced sexual harassment. Women receive significantly less research start-up funding when compared to men. Male physicians are more likely to be introduced as “doctor,” compared to female physicians. In addition, women are less likely to be first authors in top tier journals; women are less likely to be included on expert guideline consensus panels; there are fewer women in leadership positions, even in pediatrics; and there are fewer women full professors as compared to men.

• 3.
  

  Which of the following characteristics of clinical standard work is correct?

  
  
  
  
  • A.
    

    Amplifies occurrence of nuisance variables

    
    
  • B.
    

    Complicates communication among providers

    
    
  • C.
    

    Establishes a baseline for continuous improvement

    
    
  • D.
    

    Increases waste transiently with implementation

  
  

Preferred response: C

Rationale

Standardization utilizing clinical standard work facilitates identifying and eliminating waste, communicating between providers, establishing a baseline for continuous improvement, and minimizing noise/controlling for nuisance variables. Standardization represents the foundation for iterative improvement, and without standardization, measurements of improvement are not possible.

• 4.
  

  Which of the following outcomes has been reported in a dose-response fashion as a function of proportional compliance with the ICU Liberation ABCDEF bundle elements?

  
  
  
  
  • A.
    

    Decreased incidence of anemia requiring transfusion

    
    
  • B.
    

    Decreased ventilator-associated lung injury

    
    
  • C.
    

    Improved ICU and hospital survival

    
    
  • D.
    

    Increased proportion of rapid eye-movement sleep

  
  

Preferred response: C

Rationale

Two independent cohort analyses demonstrated that proportional compliance with ABCDEF bundle elements resulted in significant and dose-related improvements in patient-centered, clinically meaningful outcomes such as survival, duration of mechanical ventilation, neurological organ dysfunction (i.e., delirium and coma), use of physical restraints, ICU readmission rates, and discharge disposition of ICU survivors. Anemia, ventilator-associated lung injury, and sleep quality data have not been published.

• 5.
  

  Which aspect of simulation in an interdisciplinary teaching model is particularly effective?

  
  
  
  
  • A.
    

    Real time debriefing

    
    
  • B.
    

    Role playing

    
    
  • C.
    

    Systems thinking

    
    
  • D.
    

    Teamwork practicing

  
  

Preferred response: A

Rationale

All activities related to simulation-based education are important, but real-time team debriefing around critical events (doing in context) represents a particularly effective interdisciplinary (simulation) teaching modality.

• 6.
  

  In addition to identification of best available evidence to support best practice, what is the other benefit of a learning healthcare environment?

  
  
  
  
  • A.
    

    Encouraging empiric treatment modalities

    
    
  • B.
    

    Facilitating craftsman care attitude

    
    
  • C.
    

    Promoting wellness and resiliency

    
    
  • D.
    

    Training basic researchers

  
  

Preferred response: C

Rationale

The second, sometimes less obvious benefit of a learning healthcare environment is promoting wellness and resiliency among critical care providers. Participation of the interdisciplinary team in shared education and research/quality improvement activities provides opportunities for critical care providers to debrief and reflect, to provide mutual support, and to reinvigorate a sense of purpose.

Rationale

The majority of childhood deaths under the age of 5 years in low-and middle income countries are related to neonatal problems (34%), followed by lower respiratory (16%) and diarrheal illnesses (10%), as well as malaria (7%). Road traffic injuries play an important role in children 5 to 14 years old.

• 2.
  

  You are the attending consultant in a tertiary care center in a low-middle income country. The unit is equipped with facilities for mechanical ventilation (1 available ventilator), intermittent arterial blood gases, vasopressors, intermittent blood products. You are on call, and there are two patient calls:

  
  
  
  
  • 
    

    The first call is from the casualty senior resident for an 11-year-old child with chronic liver disease with pneumonia of 5 days duration with pediatric acute respiratory distress syndrome (PARDS) requiring mechanical ventilation and monitoring.

    
    
  • 
    

    The second call is for a child admitted in the pediatric ward. A colleague of yours is requesting shifting this 10-year-old child with a rare genetic disorder, who he followed since birth to the ICU with septic shock, PARDS, and multiorgan dysfunction. The child is also being referred from the ministry of health.

    
    
  • 
    

    Which of the following policies regarding admission to PICU are to be considered while deciding admissions in units in low resource settings?

    
    
    
    
    • A.
      

      Chronological order in which PICU requests are made do not matter.

      
      
    • B.
      

      Optimization of overall benefit that could result from use of PICU resources

      
      
    • C.
      

      Preference is to be given for requests made by the central and state health authorities or hospital administration.

      
      
    • D.
      

      The trainee can decide “who to admit” or “who not to admit’” without discussion with the attending physician.

    
    

  
  

Preferred response: B

Rationale

In resource limited countries, many children do not have access to ICUs. With a growing demand for intensive care and availability of limited resources, having policies for ICU admission therefore is of significant importance in such settings. Guidelines available for admission and discharge policies from high income countries may not be applicable to low- and middle-income countries with high burden of mortality from acute illnesses. However, the broad principles that could be adopted based on the patient population and resource availability have been discussed by Argent et al. At Red Cross War Memorial Children’s in South Africa, for example, general principles for PICU admission are the following:

• •
  

  Children will be considered for admission in terms of the chronological order in which that request is made

  
  
• •
  

  Preference will not be given to children from the Red Cross War Memorial Children’s Hospital. In fact, where possible, preference will be given to children who are referred from other areas (where they have very limited access to alternative intensive care)

  
  
• •
  

  No child will be refused admission to the PICU without a decision by the ICU attending on call at the time

  
  
• •
  

  No trainee will be asked to make a final decision about the appropriateness of PICU admission. This MUST be a consultant decision.

• 3.
  

  Which of the following statements is false regarding performance of PCCM research in low resource settings (LRS)?

  
  
  
  
  • A.
    

    Investigators in LRS would benefit from participation in networks that include other investigators within LRS and collaborations with investigators outside of LRS.

    
    
  • B.
    

    Research programs based on high-income countries should lead efforts to solve problems in LRS as they have better resources.

    
    
  • C.
    

    Research led by investigators in LRS have informed important changes in clinical guidelines for fluid resuscitation for shock and for cost-effective delivery of noninvasive respiratory support.

    
    
  • D.
    

    The research agenda for LRS should be informed by research priorities identified in LRS.

  
  

Preferred response: B

Rationale

Research priorities are ideally based on indicators such as the leading causes of child morbidity and mortality and thus vary by region. Clinicians and researchers in low-resource regions should lead prioritization of the research agenda, even though there are less research resources available including training opportunities and funding. Collaboration, research network, and training opportunities in concert with investigators and programs in high-resourced regions may serve to benefit overall strengthening of research infrastructure in low-resourced regions.

Rationale

Preparing for a potential pandemic should prompt each unit to review their own internal emergency plans and ensure all key staff are aware of how decisions will be made and communicated during the public health emergency (PHE). The primary way decisions are centralized and made with the best available information is the Incident Command System (ICS). ICU leaders will need to know what information they are expected to provide the incident command center and what decisions the incident commander will make versus what the local leaders will make. As the current resources are adequate to provide for the patients there is not a need to utilize crisis standards of care yet; hopefully conservation and contingency strategies will help avoid the need to utilize crisis standards of care. Personal protective equipment (PPE) should not be used for all patients as this will exhaust supplies of critical equipment. Manual ventilation should only be used as part of emergency mass critical care (EMCC) and when mechanical ventilators are not available; as such, this technique should not be a high priority for education and instead educational efforts should focus on reviewing the hospital and unit disasters plan for infectious outbreaks.

• 2.
  

  The emergency department calls to alert the ICU that a local shopping center building has collapsed on a Saturday with many people inside, and they are expecting many casualties to arrive within minutes. What is the correct order of steps to take?

  
  
  
  
  • A.
    

    Communicate with the incident commander, send a triage team to the ED, rapid transfer/discharge of any non-ICU level patients

    
    
  • B.
    

    Rapid assessment of surge capacity, communicate with the incident commander, send a triage team to the ED

    
    
  • C.
    

    Rapid transfer/discharge any non-ICU level patients, communicate with the ICS, assemble a triage team

    
    
  • D.
    

    Send a triage team to the ED, communicate with the incident commander, rapid assessment of surge capacity

  
  

Preferred response: B

Rationale

In any potential surge knowing the available hospital surge capacity is a critical first step. Upon notice of an incident each unit performs a rapid assessment of which patients can be safely transferred or discharged and communicates this information succinctly to the incident commander. Units should not proactively transfer or discharge patients without word from the ICS as this could result in uncoordinated, unneeded, or inappropriate allocation of resources. After alerting the incident commander, members of the ICU designated for the triage team should proceed to the ED to aid in helping with identifying patients appropriate for rapid transfer to the ICU.

• 3.
  

  A prolonged surge event due to severe influenza has caused the hospital to activate their incident command center (ICS) and utilize strategies to meet surge needs. The incident commander sends word that the ICU should begin converting OR spaces to ICU spaces, that personal protective equipment goggles should be cleaned and reused whenever possible, and that ICU staff are being asked to work overtime. What level of surge response is this?

  
  
  
  
  • A.
    

    Conventional

    
    
  • B.
    

    Contingency

    
    
  • C.
    

    Crisis

    
    
  • D.
    

    Emergency mass critical care

  
  

Preferred response: B

Rationale

Converting reasonably equipped hospital spaces to ICU space, selective reuse of supplies, and extension of existing ICU staffing pool are all contingency strategies. Conventional strategies lie in conserving resources, utilizing available staff without significantly extending staffing, substituting only where equivalent, and making use of supply caches. Crisis strategies include converting poorly equipped or non-hospital areas to ICU spaces, using non-ICU staff for ICU care, and reallocating (rationing) scarce resources. EMC refers to the global category of needing to provide ICU care to a much larger than usual number of patients.

• 4.
  

  Another hospital in the area calls to request that some of their ICU level patients be moved to your hospital’s ICU. They were the hospital closest to a school bus crash and received 15 critically ill pediatric victims from the crash. Their usual ICU capacity is 16 patients, and they were at capacity before the event. Your ICU’s usual capacity is 80 patients and it is usually >90% occupied. What size of surge did the 15 victims create at the outside hospital and what size surge would your ICU have if you accepted all 15?

  
  
  
  
  • A.
    

    Major surge at outside hospital, minor surge for your ICU

    
    
  • B.
    

    Minor surge for outside hospital, usual volume for your ICU

    
    
  • C.
    

    Moderate surge for both

    
    
  • D.
    

    Moderate surge for outside hospital, minor surge for your ICU

  
  

Preferred response: D

Rationale

For a 16 bed ICU an additional 15 patients is a 94% increase, which meets the range of a moderate surge (20–100% increase from usual capacity). For an 80 bed ICU, an additional 15 patients is an 18% increase which is a minor surge (up to 20% above usual capacity). This scenario would not constitute a major surge (>100%) for either unit.

Rationale

The six core competency domains established by the ACGME are:

• •
  

  Practice-Based Learning and Improvement

  
  
• •
  

  Patient Care and Procedural Skills

  
  
• •
  

  Systems-Based Practice

  
  
• •
  

  Medical Knowledge

  
  
• •
  

  Interpersonal and Communication Skills

  
  
• •
  

  Professionalism

  
  
  
  
  • 
    

    These six domains should be used to guide and coordinate evaluation of all residents or fellows in their development.

  
  

• 2.
  

  A critical care fellow is preparing a simulation scenario to practice communication skills during cardiopulmonary resuscitation with the bedside team. This type of simulation is an example of which of the following?

  
  
  
  
  • A.
    

    Crew Resource Management

    
    
  • B.
    

    Procedural Training

    
    
  • C.
    

    Resuscitation Manikin Teaching

    
    
  • D.
    

    Standardized Role Play

    
    
  • E.
    

    Task Training

  
  

Preferred response: A

Rationale

Crew resource management was initiated in the aviation industry to improve safety in critical environments by focusing on interpersonal communication, leadership, and decision making.

• 3.
  

  You are preparing a curriculum to teach residents about pediatric acute respiratory distress syndrome. Which of the following is an example of a method you might use that embraces adult learning principles?

  
  
  
  
  • A.
    

    Behavior management strategy

    
    
  • B.
    

    Didactic lecture using PowerPoint

    
    
  • C.
    

    See one, do one, teach one

    
    
  • D.
    

    Small group learning

    
    
  • E.
    

    Videotaped lecture with question and answer period

  
  

Preferred response: D

Rationale

Adults are self-directed and autonomous. They learn best when they are active participants in the learning process and are allowed to practice newly acquired skills and concepts. As a consequence, education is typically most effective when programs facilitate self-learning with specific goals of acquiring practical information. Efforts to be inclusive of curricular methods that support adult learning principles are occurring in undergraduate, graduate, and continuing medical education. Problem-based and small group learning, flipped classrooms, and simulation exercises allow many venues for reaching learners in different ways.

• 4.
  

  You are preparing to take the American Board of Pediatrics Critical Care Subspecialty examination. Which of the following is not required to take the examination?

  
  
  
  
  • A.
    

    A job as a pediatric intensivist

    
    
  • B.
    

    Evidence of meaningful scholarly project during pediatric critical care fellowship

    
    
  • C.
    

    Initial certification in General Pediatrics

    
    
  • D.
    

    Successful completion of a Critical Care Medicine fellowship program

    
    
  • E.
    

    Valid unrestricted license to practice

  
  

Preferred response: A

Rationale

To qualify for the ABP subspecialty examination, applicants are required to have a valid unrestricted allopathic and/or osteopathic license to practice, initial certification in general pediatrics, and successful completion of critical care medicine training in a program accredited by the ACGME. The applicant must also provide evidence of meaningful scholarship during training which can include research, an educational project, or a quality project.

• 5.
  

  You are planning to teach a group of critical care fellows how to manage a patient with acute respiratory distress syndrome. Which of the following instructional techniques takes best advantage of the qualities of the adult learner?

  
  
  
  
  • A.
    

    Attending a webinar about ventilation strategies followed by a short quiz

    
    
  • B.
    

    Engaging in a detailed review of real patient cases followed by discussion of ventilation strategies

    
    
  • C.
    

    Attending a lecture with a PowerPoint presentation followed by a quiz

    
    
  • D.
    

    Reading a research article on ARDS and then discussing the merits of the study

  
  

Preferred response: B

Rationale

Adult learners thrive with active, engaged learning environments. Although all options have the potential for active, engaged learning, response B, review of real patient cases followed by discussion of care strategy, is an example of problem-based learning and requires active engagement by the learners. It is also clearly related to their experience.

• 6.
  

  Which of the following is an example of an entrustable professional activity (EPA)?

  
  
  
  
  • A.
    

    Identifies subtle or unusual physical exam findings

    
    
  • B.
    

    Recognizes a patient requiring urgent or emergent care and initiates evaluation and management

    
    
  • C.
    

    Routinely provides vital signs and other laboratory data on rounds

    
    
  • D.
    

    Shows self-awareness of one’s own knowledge, skill, and emotional limitations that leads to appropriate help-seeking behaviors

  
  

Preferred response: B

Rationale

Domains of competence refer to the six groups of physician subcompetencies defined by ACGME, including medical knowledge, patient care, practice-based learning and improvement, interpersonal and communication skills, professionalism, and systems-based practice. Milestones are the developmental levels of knowledge, skills, and attitudes for each subcompetency and describe the progression of a physician’s ability. Entrustable professional activities (EPAs) are tasks or responsibilities that trainees are entrusted to perform unsupervised once they have attained sufficient competency. EPAs have been developed with patient safety in mind, but they also provide a framework for curricular development and lifelong progression of learning. Response B, “recognizes a patient requiring urgent or emergent care and initiates evaluation and management,” is a discrete, concrete skill that can be observed and entrusted.

Rationale

Ascertainment bias exists when those responsible for determining outcomes are aware of treatment group assignment. In this study, it would not be possible to blind bedside nurses and treating physicians to study group assignment, and knowledge of the treatment group assignment might influence their responses regarding illness trajectory. Bias due to loss of data occurs when substantial patient outcome data is missing, or when data is missing related to treatment arm assignment. Lead time bias is a risk in screening intervention studies, where time to an outcome may increase only because an illness was identified earlier than it would have naturally presented, but the screening intervention did not actually impact the occurrence of the outcome. Finally, selection bias occurs when certain patients are preferentially enrolled in the treatment or control arm of a study, creating imbalance between the study arms.

• 2.
  

  A randomized controlled trial of a biologic immunomodulating drug in patients with severe sepsis decreased mortality to 7% among patients receiving treatment, compared to 21% among patients in the control arm. Among patients with similar baseline risk of mortality, what is the number needed to treat (NNT) with this medication to save one life?

  
  
  
  
  • A.
    

    3

    
    
  • B.
    

    3.5

    
    
  • C.
    

    7

    
    
  • D.
    

    14

    
    
  • E.
    

    Not enough information to answer

  
  

Preferred response: C

Rationale

NNT is the inverse of the absolute risk reduction (ARR) × 100, or 1/(risk _untreated – risk _treated ) × 100. In this case, ARR = 21% − 7% = 14%, and 100/14 ∼7. The NNT can be adjusted for baseline risk; among septic patients with twice the baseline risk of mortality (∼42%), the NNT would be halved, at 3.5.

• 3.
  

  An interventional study for patients with traumatic brain injury randomizes half to receive an early physical therapy and mobilization bundle, compared to standard of care. What is the most appropriate statistical test to compare the hospital length of stay between the two groups?

  
  
  
  
  • A.
    

    ANOVA

    
    
  • B.
    

    Chi square test

    
    
  • C.
    

    T-test

    
    
  • D.
    

    Wilcoxon rank-sum test

  
  

Preferred response: D

Rationale

Hospital length of stay is a good example of a continuous variable with a skewed distribution, as most patients have short lengths of stay, but a handful of patients have very long lengths of stay. A nonparametric test, like the Wilcoxon rank-sum test , is most appropriate for comparing the median of this kind of outcome measure between two groups. A t-test is appropriate for comparing the mean of a normally distributed outcome measure between two groups (e.g., low-density lipoprotein cholesterol.) ANOVA is used to compare means of a normally distributed outcome measure between multiple groups. Finally, a chi square test is used to compare frequencies in a 2 × 2 table, typically used for binary outcomes.

• 4.
  

  An investigator wishes to conduct a randomized trial examining continuous renal replacement therapy (CRRT) for fluid overload in patients with severe acute respiratory distress syndrome (ARDS). Which of the following is true for this study?

  
  
  
  
  • A.
    

    If the study results demonstrate a relative risk of mortality of 0.8 in the treatment group, with a 95% CI of 0.55-1.05 and a p value of 0.12, then we can conclude that CRRT is not effective in improving outcomes for patients with severe ARDS.

    
    
  • B.
    

    Patients who are randomized to CRRT but do not receive it because their hemodialysis catheter malfunctioned should be analyzed along with patients who are in the control group.

    
    
  • C.
    

    The outcomes should be compared based on original treatment group assignment, regardless of what therapy the patient actually received.

    
    
  • D.
    

    The outcomes should be compared based on what therapy the patient actually received, regardless of original treatment group.

    
    
  • E.
    

    This study cannot be conducted because it is impossible to blind patients and providers to the treatment group assignment.

  
  

Preferred response: C

Rationale

Intention to treat analysis preserves the benefits of randomization, and patients who are randomized to a treatment group should be analyzed along with that group. It is legitimate to conduct studies in which blinding is not possible; however, study staff who ascertain subjective outcomes should be blinded to treatment group assignment. These study results suggest that there may be a treatment effect—the majority of the 95% confidence interval lies below 1.0—but, there is a reasonable probability (12%) that this estimate of effect was found by chance. It may be that there is no effect, but it may also be that this study was underpowered to identify this 20% decrease in mortality.

Rationale

PRISM scores are not designed to be interpreted for an individual patient, but instead provide a mechanism by which case-mix can be measured over a large group of patients. PRISM scores are calculated during the first 4 hours of a patient’s admission to the ICU and include physiologic and laboratory data for 2 hours prior to and 4 hours after admission. This time limitation is intended to more accurately represent a patient’s presenting physiologic status, as opposed to the provision of intensive care.

• 2.
  

  As part of a quality improvement initiative, a colleague has created a model to examine patients at risk of developing pressure injuries while in the intensive care unit. She reports in a divisional research meeting that the discrimination of the model is 0.92. Which of the following is the most correct interpretation of this value?

  
  
  
  
  • A.
    

    The model’s overall sensitivity is 92%.

    
    
  • B.
    

    The model’s overall specificity is 92%.

    
    
  • C.
    

    The positive predictive value of the test is 92%.

    
    
  • D.
    

    92% of variation in a patient’s likelihood of developing a pressure injury is explained by the model.

    
    
  • E.
    

    92% of patients with pressure injuries will meet all the components of the model.

  
  

Preferred response: B

Rationale

Discrimination is a model’s ability to correctly differentiate patients with a specified outcome from those without the outcome. This is in contrast to calibration, which is the model’s ability to predict overall event rates. The model’s discrimination is often reported as the C statistic, which represents the average sensitivity of the model over the range of possible specificity values.

• 3.
  

  A fellow is planning a research project to study patient risk factors for mortality in patients with traumatic brain injury. She is hoping to include patients from multiple centers and would like your advice about how to control for variation in risk between hospitals. Which of the following is most useful for the research team to assess?

  
  
  
  
  • A.
    

    The sample size from each hospital.

    
    
  • B.
    

    The standardized mortality ratio for each hospital.

    
    
  • C.
    

    The hospital length of stay for each included patient.

    
    
  • D.
    

    The yearly number of traumatic brain injury patients admitted to each hospital.

    
    
  • E.
    

    The presence or absence of neurosurgical services at each hospital.

  
  

Preferred response: B

Rationale

Standardized mortality ratios represent the ratio of observed to expected mortalities and provide a mechanism by which researchers can control for case mix variation between institutions. This can help to isolate patient characteristics, which are of interest to the fellow, from systems-level characteristics. While the other choices represent important considerations, the standardized mortality ratio is most important to allow for control.

• 4.
  

  A 4-month-old former 35-week gestational age girl is admitted to the intensive care unit for hypoxic respiratory failure requiring mechanical ventilation. She was intubated at an outside hospital and was started on broad spectrum antibiotics for concern for pneumonia with an elevated white blood cell count (WBC) and infiltrate on chest radiograph. As part of her admission process, the bedside nurse completes a worksheet with information for the Pediatric Risk of Mortality (PRISM) score as well as the Paediatric Index of Mortality-3 (PIM3) score. Which of the following pieces of information will be included in the PIM3 but not PRISM?

  
  
  
  
  • A.
    

    The pH from an arterial blood gas obtained one hour after admission.

    
    
  • B.
    

    The measured systolic blood pressure at admission.

    
    
  • C.
    

    The results of pupillary reflex testing.

    
    
  • D.
    

    The fact that the child is undergoing mechanical ventilation.

    
    
  • E.
    

    The measured WBC obtained at the outside hospital one hour prior to admission.

  
  

Preferred response: D

Rationale

Both PIM3 and PRISM include evaluation of physiologic and clinical data for a patient but the methods differ slightly in the amount of included data, the observation period, and inclusion of nonphysiologic data. Specifically, PIM3 includes mechanical ventilation within an hour of admission, while PRISM includes more laboratory values. Both scoring systems include evaluation of systolic blood pressure and pupillary reflexes.

• 5.
  

  A researcher develops a model to predict the risk of patients admitted to the PICU of developing a deep venous thrombosis based on a number of demographic and clinical factors. The model is developed on 1000 patients with an area under the receiver operating characteristic curve (AUC) of 0.8. The model is subsequently validated on a separate dataset of 1000 patients with an AUC = 0.7. What term best describes the model’s performance as quantified by the AUC?

  
  
  
  
  • A.
    

    Calibration

    
    
  • B.
    

    External validity

    
    
  • C.
    

    Discrimination

    
    
  • D.
    

    Internal validity

  
  

Preferred response: C

Rationale

Discrimination is the accuracy of a model in differentiating outcomes groups and is most often assessed by the AUC. External validity is the extent to which the results of a study can be generalized to other situations and other people. External validity is typically assessed through the process of study replication. Calibration refers to the ability of a model to assign the correct probability of outcome to patients over the entire range of risk prediction. The most accepted method for measuring calibration is the Hosmer-Lemeshow goodness-of-fit test. Internal validity relates to the extent to which a causal conclusion based on study findings is warranted and is assessed by the degree to which the study design minimized systematic error or bias. The precision of a measurement system is the degree to which repeated measurements under unchanged conditions show the same results.

• 6.
  

  A previously healthy 7-year-old male is admitted to the PICU of a tertiary care children’s hospital in septic shock secondary to lobar pneumonia. He is tachycardic (heart rate, 130 beats per minute) and tachypneic (respiratory rate, 55 breaths per minute) and undergoes intubation of the trachea within 30 minutes of PICU admission for respiratory failure. Arterial blood gas reveals pH = 7.2, Paco ₂ = 40 mm Hg, Pao ₂ = 80 mm Hg, and HCO ₃ ⁻ = 12 mEq/L on F io ₂ of 0.6. Coagulation studies reveal an elevated INR = 1.8. Which scoring system is most appropriate to assess this patient’s physiologic status on the initial day of PICU admission?

  
  
  
  
  • A.
    

    PELOD

    
    
  • B.
    

    PRISM III

    
    
  • C.
    

    SNAPPE-II

    
    
  • D.
    

    STS-EACTS score

  
  

Preferred response: B

Rationale

CRIB II and SNAPPE-II are scoring systems for neonates. STS-EACTS score was developed for patients with congenital heart disease. PELOD is a scoring system designed to quantify the degree of organ dysfunction in PICU patients and correlates well with mortality. PELOD, however, is calculated based on the greatest degree of physiologic dysfunction to occur at any point during the entire PICU admission, not just the initial day of admission. PRISM III is a physiology-based acuity score that is calculated in the interval from the 2 hours preceding PICU admission to 4 hours following PICU admission.

• 7.
  

  You are asked to accept the transfer of a 2-year old child with respiratory failure secondary to viral pneumonitis from a rural emergency department (ED). The child was seen and discharged from that ED 2 days ago. This morning, her parents awoke to her loud breathing and called emergency medical services. The emergency medical technicians assessed the child, determined that she had respiratory failure, stabilized her airway, provided bag-valve-mask ventilation with oxygen, and provided respiratory treatments during transport to the local ED. They notified the ED of the child’s condition. The ED is performing additional steps for stabilization, along with some diagnostic tests, including a chest radiograph and basic laboratory studies. The ED has explained to the family that their child will need to be transported to the local children’s hospital, and someone from the ED is calling you for a helicopter transport. This scenario demonstrates appropriate system design for the critically ill child around which of the following issues?

  
  
  
  
  • A.
    

    Access

    
    
  • B.
    

    Cost

    
    
  • C.
    

    Outcome

    
    
  • D.
    

    Process

  
  

Preferred response: A

Rationale

Systems are designed to facilitate easy access to services for those who need them. Access (response A) describes organized and integrated care for critically ill children and their families who are in need of tertiary pediatric services. Cost (response B) is an important element of healthcare delivery that focuses on the monetary resources devoted to patient care. However, economic terms are not discussed in this scenario. Research is an important activity in generating new knowledge, but this scenario is concerned with the delivery of care to an individual patient. Although the child ultimately may be enrolled in a research project or database evaluating outcomes, research is not the primary focus of her care. Process measures (response D) are those that occur between patients and providers or between various providers. Although a number of clinical processes have occurred in the scenario, the scenario also includes a number of interactions between other structural components, such as institutions and emergency services, which establish an organized hierarchy of interactions for the delivery of care. The final outcomes of care from the ICU perspective (response C) are not discussed in the scenario. Although the child was effectively rescued and delivered to the rural ED and a number of intermediate outcomes may be described, the final outcomes in terms of vitality, economics, or morbidity are yet to be determined. Therefore, the most appropriate answer is A.

• 8.
  

  After the first ICU day, the child’s PRISM III score is 8. What should you do?

  
  
  
  
  • A.
    

    Ignore the score for today.

    
    
  • B.
    

    Remove the child from mechanical ventilation and provide comfort care.

    
    
  • C.
    

    Rescore the patient using the Pediatric Index of Mortality (PIM).

    
    
  • D.
    

    Recognize that this score is correlated with a population risk of mortality.

  
  

Preferred response: D

Rationale

The PRISM score is a physiologically based severity of illness measure calculated from variables determined within the first 24 hours of care. It is helpful for understanding the risks for mortality and length of stay for populations of patients with a given severity of illness. However, the score cannot be applied for prognostication at the level of individual patients; hence it should not be used to guide clinical decisions as suggested in response B. Repetitive scoring using PRISM during hospitalization (response A) has not been validated. Using the PIM (response C), which captures care at the point of admission rather than at 24 hours, provides a different measure of severity that also can be compared across populations. Importantly, a bias exists in relation to the inclusion of mechanical ventilation as a predictor variable in PIM. Therefore the most appropriate answer is D.

Rationale

The advantages of ground transport include easier and direct access to referring and receiving locations, lower cost, and ability to respond in most weather conditions. Circumventing traffic rules via use of lights and sirens does not improve the outcomes of pediatric transports and significantly increase the risk of an accident. Rotor-wing (helicopter) transport may be faster than ground transport for patients located 45–60 miles away from admitting institution, particularly in geographically challenging areas such as waterways, and can help to minimize out-of-hospital time. Fixed-wing transports are typically reserved for long-distance flights and have the ability for cabin pressurization. Disadvantages of both rotor-wing and fixed-wing transports are limited space and high cost.

• 2.
  

  A pediatric patient is intubated for acute respiratory failure secondary to pneumonia at a critical access hospital and now requires rotor-wing transport to the nearest pediatric intensive care unit for ongoing care. The referring facility is located at an altitude of 718 ft above sea level where the atmospheric pressure is 741 mm Hg. The flight path will take the patient over a mountain pass with an unpressurized cabin altitude equivalent to 5100 ft above sea level and an atmospheric pressure of 630 mm Hg. If the endotracheal tube cuff is inflated with 2 mL of air prior to departure from the referral facility, what is the expected volume of air in the cuff when at the highest altitude?

  
  
  
  
  • A.
    

    1.5 mL

    
    
  • B.
    

    2.4 mL

    
    
  • C.
    

    3.0 mL

    
    
  • D.
    

    3.2 mL

  
  

Preferred response: B

Rationale

Boyle’s law (P ₁ V ₁ = P ₂ V ₂ ) describes the relationship between pressure and volume of a gas in an enclosed space at a constant temperature. Given that this patient will be rising in altitude, atmospheric pressure is expected to decrease with increasing height. Any gases trapped in enclosed spaces are expected to expand proportionately to any decreases in atmospheric pressure. Substituting the known pressures and volumes into the equation allows for calculation of the unknown cuff volume at the highest altitude:

• 3.
  

  According to the Emergency Medical Treatment and Labor Act (EMTALA) established by the COBRA legislation, an appropriate transfer criterion includes which of the following?

  
  
  
  
  • A.
    

    The referring hospital must provide care and stabilization within its ability.

    
    
  • B.
    

    The referring physician certifies that the medical benefits expected from the transfer outweigh the risks.

    
    
  • C.
    

    The referring physician consents to transfer after being informed of the risks of transfer.

    
    
  • D.
    

    The receiving facility must have available space and qualified personnel and agree to accept the transfer.

  
  

Preferred response: B

Rationale

EMTALA delineates rules for inter-facility transfer. Appropriate transfers must meet the following criteria: (1) the transferring hospital must provide care and stabilization within its ability; (2) the referring physician certifies that the medical benefits expected from the transfer outweigh the risks; (3) the patient consents to transfer after being informed of the risks of transfer; (4) the receiving facility must have available space and qualified personnel and agree to accept the transfer; (5) copies of medical records and imaging studies should accompany the patient; and (6) the inter-facility transport must be made by qualified personnel with the necessary equipment.

• 4.
  

  Which of the following characterizes a typical skilled inter-facility pediatric transport team in comparison to care providers at a referring hospital?

  
  
  
  
  • A.
    

    Administration of drugs not typically available at non-tertiary centers

    
    
  • B.
    

    Aggressive, early institution of simple therapies

    
    
  • C.
    

    Availability of superior airway and breathing support modalities

    
    
  • D.
    

    Superior diagnostic capabilities

  
  

Preferred response: B

Rationale

For most pediatric critical illnesses, definitive care, ideally beginning with a skilled inter-facility transport team, does not involve miracle drugs or technologies but rather the early, aggressive administration of simple therapies. Therapy that includes timely initiation of resuscitation fluids, early administration of inotropes (frequently via peripheral intravenous or intraosseous catheters), and early antibiotic therapy can improve outcomes.

Rationale

CRBSI is the most common complication related to CVCs. In children, the location of the insertion site is not related to infection risk. The risk of infection is decreased by the use of a bundle of practices during insertion and ongoing maintenance of the CVC. The insertion bundle includes strict maximal sterile barrier precautions and aseptic technique. Dressing changes with chlorhexidine skin prep, minimizing catheter access, and daily assessment of the need of the catheter are all recommended as a part of CVC maintenance. Antimicrobial-impregnated catheters may decrease the risk of catheter-related infection, but more pediatric studies are needed.

• 2.
  

  Which of the following is the most common complication of intraosseous (IO) infusion?

  
  
  
  
  • A.
    

    Fat embolus requiring mechanical ventilation

    
    
  • B.
    

    Fracture requiring internal fixation

    
    
  • C.
    

    Hypercalcemia from bone demineralization

    
    
  • D.
    

    Infiltration of fluids into the surrounding tissues

  
  

Preferred response: D

Rationale

Significant complications of IO insertion and infusion are rare. The most common complication is extravasation of fluid. The causes of extravasation include incomplete penetration of the bony cortex, movement of the needle such that the hole is larger than the needle, dislodgment of the needle, penetration of the posterior cortex, and leakage of fluid through another hole in the bone, such as a previous IO site or fracture. Extravasation of a small amount of fluid is usually not problematic, but with larger volumes, compartment syndrome can develop and may require fasciotomy and even amputation. Use of the IO line for prolonged periods or with pressure bags increases the risk for this complication. If extravasation occurs, the needle should be removed, and the extremity diligently observed for signs of compartment syndrome. Experience to date suggests that the complications of the new mechanical insertion devices are similar to manual IO needle use.

Other rare complications include infection and bone fracture. Osteomyelitis, cellulitis, and sepsis have been reported in conjunction with IO infusion. Risk for infection is increased when IO access is prolonged, and these devices are used in patients with bacteremia.

• 3.
  

  Ultrasound guidance for needle pericardiocentesis should be standard practice for which of the following indications?

  
  
  
  
  • A.
    

    Cardiac tamponade with ongoing cardiopulmonary resuscitation

    
    
  • B.
    

    Elective pericardiocentesis with idiopathic pericarditis

    
    
  • C.
    

    Penetrating trauma of the right ventricle

    
    
  • D.
    

    Second procedure after a failed blind, landmark-based attempt

  
  

Preferred response: B

Rationale

Except in life-threatening tamponade, ultrasound imaging should be used to improve success and reduce complications. Drainage of a pericardial effusion due to any cause is absolutely indicated when cardiac tamponade is present. Often drainage is recommended if the effusion is large, even in the absence of tamponade, for diagnosis and fluid removal. For small effusions, pericardiocentesis may be indicated for diagnosis alone. With purulent pericarditis, open surgical drainage may be more effective because of the difficulty in draining purulent exudate. Traumatic pericardial effusions secondary to penetrating trauma often require surgical drainage of the blood, because tamponade is common. Pneumopericardium secondary to pulmonary air leaks in mechanically ventilated patients is usually well tolerated hemodynamically but may require drainage, especially in small infants, because of the development of tamponade.

There is no absolute contraindication to pericardiocentesis in an emergency situation. The presence of aortic dissection or myocardial rupture is considered a major contraindication. The presence of a bleeding diathesis or coagulopathy is another contraindication. Open drainage is preferred over closed drainage when the patient has traumatic tamponade and is in cardiac arrest. When the effusion is loculated in a location not easily reached via the subxiphoid approach, needle pericardiocentesis is contraindicated because the risk of complications increases, while the possibility of successful drainage is low.

• 4.
  

  Which of the following is most consistent with an exudative pleural effusion?

  
  
  
  
  • A.
    

    Pleural to serum lactate dehydrogenase (LDH) ratio < 0.4

    
    
  • B.
    

    Pleural fluid LDH < the upper limit of normal serum LDH value

    
    
  • C.
    

    Pleural to serum protein ratio > 0.5

    
    
  • D.
    

    Pleural fluid WBC count <5% of peripheral WBC count

  
  

Preferred response: C

Rationale

Analysis of pleural fluid is separated into two basic diagnostic categories: exudates and transudates. Transudates arise from imbalances of hydrostatic or oncotic pressures, such as seen in congestive heart failure or nephrotic syndrome. Exudates can be caused by a variety of mechanisms, most commonly from pleural and lung inflammation or impaired lymphatic drainage. The criteria used to distinguish between the two have evolved, but are rooted in Light’s Criteria Rule (see below). The updated combination of two or more of these criteria increases the diagnostic sensitivity for the rule. More recent diagnostic rules, including the “two-test rule” and “three-test rule,” include pleural fluid cholesterol level greater than 45 mg/dL and do not require concomitant serum levels to be obtained.

Additional pleural fluid studies should be sent to aid in diagnosis, especially fluid for culture, cell count with differential, and cytology. Low pleural glucose (<60 mg/dL) and pleural pH (<7.3) with very elevated nucleated cell counts (>50,000/mL) are highly suggestive of empyema. Elevated pleural triglyceride levels (>110 mg/dL) and lymphocyte predominance suggest chylothorax, while triglycerides <50 mg/dL effectively rule it out. Elevated amylase suggests pancreatitis or esophageal rupture. Advances in polymerase chain reaction (PCR) technology allow for rapid and accurate diagnosis of viruses and bacteria in pleural fluid.

Light’s criteria rule for diagnosing exudative effusions are as follows: If at least one of the following present, effusion defined as exudate:

• •
  

  Pleural to serum protein ratio >0.5

  
  
• •
  

  Pleural to serum lactate dehydrogenase (LDH) ratio >0.6

  
  
• •
  

  Pleural fluid LDH more than twice the upper limit of normal serum LDH value

• 5.
  

  Which of the following is suggestive of spontaneous bacterial peritonitis when evaluating fluid obtained from a paracentesis?

  
  
  
  
  • A.
    

    Ascitic fluid glucose 22 mg/dL with serum glucose 110 mg/dL

    
    
  • B.
    

    Multiple organisms in the culture

    
    
  • C.
    

    Neutrophils ≥250/mm ³

    
    
  • D.
    

    Total protein 2.2 g/dL

  
  

Preferred response: C

Rationale

• 6.
  

  Initial management of limb ischemia after arterial catheterization should include which of the following?

  
  
  
  
  • A.
    

    Aspirin and local application of nitroglycerin paste

    
    
  • B.
    

    Catheter removal and systemic heparin anticoagulation

    
    
  • C.
    

    Local infusion of alteplase

    
    
  • D.
    

    Thrombectomy within 4 hours

  
  

Preferred response: B

Rationale

Limb ischemia that develops after arterial catheterization first requires immediate catheter removal. If ischemia does not rapidly resolve and no contraindications to anticoagulation exist, heparinization should be considered. In larger vessels, thrombectomy or local infusion of thrombolytic agents such as alteplase may be considered in consultation with vascular surgeons and interventional radiologists.

• 7.
  

  During an ultrasound-guided pericardiocentesis, saline microbubble contrast (saline solution in a syringe that has been agitated) injected through the introducer needle demonstrates the appearance of contrast in the left ventricle. The most appropriate next step is:

  
  
  
  
  • A.
    

    Alerting a cardiovascular operative team for emergency open pericardiotomy

    
    
  • B.
    

    Catheter placement, followed by high-resolution computed tomography coronary arteriography

    
    
  • C.
    

    Insertion of the guidewire

    
    
  • D.
    

    Removal of the needle

  
  

Preferred response: D

Rationale

Several techniques are helpful to determine if blood obtained during pericardiocentesis is of cardiac or pericardial origin. One technique involves injection of small amounts of saline microbubble contrast (saline solution in a syringe that has been agitated) through the introducer needle while imaging with echocardiography. If contrast bubbles are seen in the heart, then the tip of the needle is intracardiac and should be removed. If bubbles appear in the pericardial sac, then the needle is appropriately placed in the pericardium.

Rationale

Placement of central venous catheters using active ultrasound guidance has been demonstrated to be superior to marking position prior to the procedure. Generalizable studies that demonstrate a significant safety benefit for subclavian vein central venous cannulation under ultrasound in children remain lacking. Advantages of ultrasound use for arterial catheter and umbilical vein catheter placement have been described. There have not been sufficient studies to determine whether transverse or longitudinal guidance approaches for vascular access are advantageous.

• 2.
  

  Which of the following statements is true regarding cardiac ultrasonography by intensivists in children?

  
  
  
  
  • A.
    

    It demonstrates good concordance with studies performed and interpreted by expert echocardiographers.

    
    
  • B.
    

    It is useful in cardiac arrest to determine the likelihood of failed return of spontaneous circulation (ROSC) if the heart is not moving.

    
    
  • C.
    

    It is not affected by high intraabdominal pressure.

    
    
  • D.
    

    When used for determining intravascular volume status, identical criteria for IVC measurement should be used for mechanically ventilated and spontaneously breathing patients.

  
  

Preferred response: A

Rationale

Cardiac ultrasonography by pediatric intensivists and emergency medicine physicians has demonstrated good concordance in terms of both interpretation and image acquisition with ICU ultrasound equipment. Though adult cardiac arrest studies have demonstrated cardiac standstill may predict failure to achieve ROSC, recovery of cardiac function in children on ECMO initiated during CPR has also been described. Increased intrathoracic pressure with mechanical ventilation affects the measurement of the inferior vena cava (IVC) for volume status assessment as well. Accordingly, heart position is also affected by elevated intrathoracic or intraabdominal pressures due to position of the diaphragm and lungs in these clinical scenarios.

• 3.
  

  What is true regarding pulmonary ultrasound in critically ill children?

  
  
  
  
  • A.
    

    It demonstrates reduced visibility of lung parenchyma and pulmonary vascular structures as consolidation progresses.

    
    
  • B.
    

    It is affected by changes in body composition, development, and size throughout the growth of a child.

    
    
  • C.
    

    It is prone to artifactual findings, which should be ignored during interpretation of the image.

    
    
  • D.
    

    It should be performed with a phased array transducer.

  
  

Preferred response: B

Rationale

The appearance of the lung changes throughout pediatric development as infant body water decreases and bones ossify. Early in life, intrathoracic structures may be more visible because of less impedance from lung and bony structures. Through late childhood into adolescence, ongoing growth affects available windows and the depth of visualization in patients. A phased array transducer can visualize areas within the thorax and the pleural line; however, this is not optimal for visualizing pleural sliding because the field of view with this type of sector transducer is narrow near the skin. Artifactual pulmonary ultrasound findings, such as B- and Z-lines, have been described as useful for assessing pediatric pulmonary pathology and should be incorporated into the assessment. Consolidation of lung parenchyma increases visualization of structures due to less interference from air as it is excluded from the tissue. B-lines are not apparent in pneumothorax due to separation of the visceral pleura from the chest wall.

Rationale

Explicit support of family decision-making, higher proportion of family speech, increased use of empathetic statements and expressing nonabandonment are all elements of high quality communication that is associated with increased patient survival, family and patient satisfaction, and is protective against physician and nursing burnout. Conflict is abundant in clinical practice. It may be unavoidable. Rather than side-stepping conflict, collaborative communication helps physicians identify conflict as an opportunity to develop a more complete understanding of the family’s differing perspectives.

• 2.
  

  Parental presence during invasive procedures and cardiopulmonary resuscitation has been shown to:

  
  
  
  
  • A.
    

    Complicate the ability of clinicians to teach trainees procedural skills

    
    
  • B.
    

    Increase the likelihood of adverse events

    
    
  • C.
    

    Increase parental emotional lability

    
    
  • D.
    

    Negatively impact physicians’ technical performance

    
    
  • E.
    

    Reduce parental anxiety surrounding their child’s care

  
  

Preferred response: E

Rationale

Parental presence during invasive procedures and cardiopulmonary resuscitation is associated with improved satisfaction, better understanding, reduced anxiety, better coping, more emotional stability, and improved adjustment to a child’s death. Parental presence during procedures or resuscitation has not been associated with negative impacts on technical performance, ability to teach, adverse events, or clinical decision making.

• 3.
  

  In general, what is the primary cause of stress in parents related to the admission of their child to an ICU?

  
  
  
  
  • A.
    

    They are concerned about the cost of care.

    
    
  • B.
    

    They are afraid their child will die.

    
    
  • C.
    

    They are stressed about being separated from their child.

    
    
  • D.
    

    They are concerned their child will not be the same after leaving the hospital.

  
  

Preferred response: C

Rationale

The admission process can be frightening for the parents and child, especially when the admission is emergent or unplanned. Every effort should be extended to help the parents acclimate to the new environment; they should be treated with compassion and courtesy, and time should be taken to meet their needs. Parents report a loss of control, which can be unbearable when they are separated from their ill child. To support the child and the parents, caregivers should invite the parents to be part of the admission process and enable them to remain with their child to the extent possible.

Rationale

The substituted judgment standard applies to situations in which the surrogate decision makers know what the patient would have wanted. Very young children are unable to communicate what they want. Even older children often have not have developed the ability to consider and verbalize their preferences about complex medical decisions prior to becoming incapacitated. Therefore, utilization of the best interest standard (as opposed to substituted judgement) as the basis of surrogate decision-making is most common in pediatrics. In situations where an older adolescent (commonly living with chronic medical conditions) has considered and conveyed their wishes to adults prior to the losing the ability to participate in decision-making, substituted judgment is appropriate to utilize in making surrogate medical decisions. In all situations where the wishes of the patient are unknown, the best-interest standard is the most appropriate decision-making tool.

• 2.
  

  Which of the following statements regarding adolescent decision-making is true?

  
  
  
  
  • A.
    

    A 15-year-old patient can seek medical care for reproductive and mental health needs without parental consent.

    
    
  • B.
    

    Adolescents are typically not developmentally ready to participate in discussions about their medical care.

    
    
  • C.
    

    Adolescents are legally required to provide assent as part of the informed consent process.

    
    
  • D.
    

    Pediatric patients designated as mature minors are still required to have adult caregiver consent for significant medical decisions.

  
  

Preferred response: A

Rationale

In pediatrics, parents or legal guardians must provide informed consent for non-adult children. If children are 7 years of age or older, their informed assent is desired but not legally required. However, there are exceptions. Adolescents who qualify as mature minors can provide consent for themselves. Similarly, all states allow adolescents to provide consent for specific healthcare needs like reproductive health and mental health services after a certain age (usually 14 or 15). Regardless of legal decision-making authority, clinicians should strongly consider including adolescents in medical decisions and should work with adolescents and their families to achieve agreement whenever possible.

• 3.
  

  During an influenza outbreak, the PICU is running out of ventilators. The MOST appropriate allocation strategy is:

  
  
  
  
  • A.
    

    Adhere to your institution’s predetermined standardized triage criteria

    
    
  • B.
    

    Perform a lottery

    
    
  • C.
    

    Prioritize neonates over older children since they have a longer life expectancy

    
    
  • D.
    

    Withdraw the ventilators from patients least likely to survive

  
  

Preferred response: A

Rationale

Allocation decisions for scarce resources are best made in advance, before a period of surge. This prevents triage decisions from being made at individual bedsides and eliminates potential injustices. Every institution should have a disaster plan in place to deal with surges—natural or manmade.

• 4.
  

  A 3-year-old girl suffered a cardiac arrest following cardiac surgery. She has had minimal neurologic recovery. She has been in the CICU for 5 months with chronic critical illness. Her parents adamantly demand that everything medically possible be done for her despite ongoing communication with the medical team. Many members of the medical team are distressed at caring for this patient and advocate for withdrawal of life support. The most appropriate response from the medical team is:

  
  
  
  
  • A.
    

    Allow distressed staff to refuse to care for the child

    
    
  • B.
    

    Continue to tell the family daily that their child is suffering and that life support should be withdrawn

    
    
  • C.
    

    Continue to support the family and the medical team, and engage the ethics consult service to apply a fair process-based approach to evaluate if continuing medical therapies is potentially inappropriate

    
    
  • D.
    

    The medical team should tell the family that life support will be withdrawn against their wishes

  
  

Preferred response: C

Rationale

Clinicians cannot simply refuse to care for a child based on a claim of moral distress, or unilaterally withdraw life-support against a family’s wishes without a fair process. The medical team should continue to support the family and staff through these challenging times, working diligently to maintain open lines of communication and trust with the family.

• 5.
  

  Which of the following is a true statement regarding the doctrine of informed consent?

  
  
  
  
  • A.
    

    Decisions must be voluntary and not subject to coercion, manipulation, or undue influence.

    
    
  • B.
    

    It does not apply to decisions involving research.

    
    
  • C.
    

    The patient needs to understand all the minutia of the treatment being discussed.

    
    
  • D.
    

    The decision making should be shared with a competent medical provider.

  
  

Preferred response: A

Rationale

The doctrine of informed consent applies to both medical decisions and research. Informed consent must satisfy four requirements that apply when surrogates provide permission as well as when consent is obtained directly from patients. With disclosure, the clinician should supply the patient with sufficient information that a “reasonable person” would desire to be able to make an informed medical decision. With understanding, the clinician should assess the patient’s understanding of the proposed course of action, the risks and benefits of that course of action, and any available alternatives along with the risks and benefits associated with those actions. Understanding may be particularly impaired in the critical care setting where the high stakes and time pressures can impact the ability to achieve optimal understanding. With capacity, the patient must meet legal requirements for competency, be able to understand the medical decision, form a reasonable judgment based on the consequences of the decision, and be able to communicate that decision to others. Legally, children under the age of 18 are not considered competent for medical decision making with the exception of emancipated and mature minors. Emancipated minors are considered competent based on characteristics that are defined by state law, but may include pregnancy, parenthood, or establishing financial independence. Mature minors represent another category that is defined by state law whereby a minor, usually above a certain age, can be judged competent to make certain medical decisions. Most states require a judge to make these determinations, and the judge may restrict the determination to the medical decisions at hand. With voluntariness, decisions must be voluntary and not subject to coercion, manipulation, or undue influence. Importantly, physicians should not withhold or deemphasize information in an effort to manipulate patients.

• 6.
  

  Which of the following is an important consideration that may justify seeking legal intervention to override a parent’s decision to refuse a medical therapy?

  
  
  
  
  • A.
    

    Mediation and negotiation efforts are initiated and conducted by the state courts.

    
    
  • B.
    

    Parental authority is absolute and cannot be challenged legally by medical professionals.

    
    
  • C.
    

    The intervention refused by the parent is one that is not commonly performed.

    
    
  • D.
    

    The parent’s decision places the child at a significant risk of serious harm.

  
  

Preferred response: D

Rationale

In most situations, parents are granted wide latitude in the decisions they make on behalf of their children, and the law has respected those decisions except when they place the child’s health, well-being, or life in jeopardy. Parental authority is not absolute, however, and when a parent or guardian fails to adequately guard the interests of a child, the decision may be challenged, and the state may intervene. A clinician’s authority to interfere with parental decision making is limited. Except in emergency situations where a child’s life is threatened imminently or a delay would result in significant suffering or risk to the child, the physician cannot do anything to a child without the permission of the child’s parent or guardian. Touching (physical examination, diagnostic testing, or administering a medication) without consent is generally considered battery under the law. The clinician’s options include either tolerating the parents’ decision (while continuing to try to convince them to act otherwise) or involving a state agency to assume medical decision-making authority on behalf of the child.

Only the state can order a parent to comply with medical recommendations. This can take different forms, but most frequently either includes involvement of child protective services (under a claim of medical neglect) or a court order. Both of these options represent a serious challenge to parental authority, and parents will generally perceive them as disrespectful and adversarial. Such action interferes with family autonomy, can adversely affect the family’s future interactions with medical professionals, and can negatively impact the emotional well-being of the child. Neither should be undertaken without serious consideration. Before initiating the involvement of state agencies to limit parental authority and override parental refusal, the clinician must establish that (1) the recommended course of action is likely to benefit the child in an important way, (2) the treatment is of proved efficacy with a reasonable likelihood of success, (3) the parent or surrogate’s decision to refuse intervention places the child at significant risk of serious harm in comparison to the recommendations of the healthcare team (applying the harm principle), and (4) all attempts at mediation and negotiation to find a mutually acceptable solution have been exhausted.

Rationale

The parents have a long established legal and ethical right to make decisions for their child, but they may not demand therapy that the physician deems inappropriate. However, before escalating the situation further, it is most appropriate to invest all necessary time and energy into listening to their concerns and fostering respectful communication by holding a family meeting as the next best step.

• 2.
  

  The parents and the attending physician have made the decision to withdraw life-sustaining treatment from the 10-year-old patient with recurrent AML, now one month post-stem cell transplant with progressive multiple organ failure. Which of the following options reflects current thinking in medical ethics:

  
  
  
  
  • A.
    

    Neither withholding life-sustaining treatments nor withdrawing life-sustaining treatments is allowed without the assent of the 10-year old child in addition to the permission of the parents.

    
    
  • B.
    

    There is no ethical distinction between withholding life-sustaining treatments and withdrawing life-sustaining treatments

    
    
  • C.
    

    Withdrawing life-sustaining treatments is more ethical than withholding life-sustaining treatments

    
    
  • D.
    

    Withholding life-sustaining treatments is more ethical than withdrawing life-sustaining treatments.

  
  

Preferred response: B

Rationale

There is no morally relevant or logically valid distinction between withholding and withdrawing life-sustaining treatments in mainstream bioethics or in the law in the United States. They are considered to be the same.

• 3.
  

  The decision is made to withdraw mechanical ventilation on a 10-year-old patient with recurrent AML, now one month post-stem cell transplant with progressive multiple organ failure and allow her to die. Which of the following options reflects current thinking in medical ethics on the goal of administering sedatives and analgesics in this context:

  
  
  
  
  • A.
    

    To hasten the patient’s death

    
    
  • B.
    

    To relieve the parent’s anxiety

    
    
  • C.
    

    To relieve the team’s anxiety

    
    
  • D.
    

    To treat patient discomfort

  
  

Preferred response: D

Rationale

The goal of administering these therapies is only to treat patient discomfort and not to hasten the dying process or treat concerns of family members or the team with medication to the patient.

• 4.
  

  The decision is made to withdraw mechanical ventilation on a 10-year-old patient with recurrent AML, now one month post-stem cell transplant with progressive multiple organ failure and allow her to die. Which of the following might be indicated in this context?

  
  
  
  
  • A.
    

    Antisialagogue

    
    
  • B.
    

    Caffeine

    
    
  • C.
    

    Neuromuscular blocking agent

    
    
  • D.
    

    Potassium

  
  

Preferred response: A

Rationale

Medications that have no comfort relieving properties, but will hasten the death of the patient, such as neuromuscular blocking agents, potassium, and calcium are contraindicated in this context. Similarly, caffeine would work at odds with sedatives and analgesics in a patient in this context. An antisialagogue might be indicated in this context to reduce the secretion burden in this patient being extubated from mechanical ventilation with the goal of allowing her to die.

Rationale

There is long-standing legal and moral precedent that pain and suffering at the end of life can and should be treated, and fears of legal repercussions should not prevent physicians from treating patients appropriately. It is also generally accepted, and supported by a series of court cases, that any medical technology can be discontinued if it is no longer providing a benefit to the patient, no longer desired by the competent adult patient, or merely prolonging imminent death. For children, parents are assumed to be the legal decision-makers except in unusual circumstances. Typically, there is little controversy when parents and the medical team agree on goals of care, the withdrawal of technology that is no longer helpful, and the management of suffering. The Doctrine of Double Effect is often used as an ethical justification for providing medications to treat pain and suffering at the end of life, since there is also a possibility that they will hasten death. The components that make the unintended consequence justifiable include:

• 1.
  

  The act itself (treating suffering) must be inherently good

  
  
• 2.
  

  The agent intends the good effect (treating suffering) rather than the bad effect (hastening death)

  
  
• 3.
  

  The good effect must outweigh the bad effect (e.g., hastening death by many years for mild pain would be unacceptable)

Many add that the bad effect must not be a means to the good effect—meaning death is not used as the means to end suffering. Practically, these arguments can shed light on what medications may or may not be acceptable to use at the end of life. Medications that treat pain or other symptoms should be used in reasonable doses based on the patient’s prior exposure and expected tolerance and may be escalated rapidly as needed for untreated symptoms. Medications that are unacceptable are those that would merely hasten the dying process without treating suffering (e.g., neuromuscular blockade, potassium chloride).

In the vignette, it would be appropriate to give any of the sedative or opioid agents listed with an intent to treat pain or dyspnea, even if the respiratory drive might be suppressed or the intracranial pressure affected. Vecuronium, however, would be inappropriate as the ventilator is being withdrawn since neuromuscular blockade would hasten death without treating suffering (and in fact would potentially make it difficult to detect distress). Agents that are considered to provide deep sedation (e.g., ketamine or propofol) are typically considered only when other agents have proven ineffective or when the patient is known to be very tolerant to less sedating agents, but their use can still be justified.

• 2.
  

  You are caring for an 8-year-old boy with end-stage metastatic osteosarcoma, with extensive bony and lung metastases. He was admitted to the PICU from home due to a pain crisis that could not be adequately controlled by his hospice team. He is currently on a hydromorphone PCA (patient-controlled anesthesia), with both a basal rate and a demand dose. You are escalating the dose aggressively, and he continues to complain of refractory pain, particularly in his right humerus and right scapula. Which of the following adjunctive pain treatments would be LEAST appropriate in this setting?

  
  
  
  
  • A.
    

    Bisphosphonates

    
    
  • B.
    

    Epidural analgesia

    
    
  • C.
    

    Ketamine

    
    
  • D.
    

    Lidocaine patch

    
    
  • E.
    

    Steroids

  
  

Preferred response: B

Rationale

Steroids and bisphosphonates are important adjuvant therapies for bone pain that is refractory to opiates. Ketamine would be a reasonable addition to the hydromorphone PCA, given its distinct mechanism of action (NMDA-antagonist) and its potential to help alleviate any component of neuropathic pain. Lidocaine patches can be useful adjuncts, particularly when the pain is highly localized to one or two areas. Epidural analgesia can be an invaluable adjunctive therapy for refractory pain in end-stage cancer, as long as the site of pain is at the chest or below. This patient’s site of pain (shoulder and scapula) would be inappropriately high to place an epidural catheter.

• 3.
  

  You are caring for a 2-year-old boy, formerly a 26-week premature infant, with chronic respiratory failure due to bronchopulmonary dysplasia, dependent on mechanical ventilation via a tracheostomy tube. He also has global developmental delay and a seizure disorder. He is admitted to the PICU with severe pneumonia, sepsis, and multiorgan dysfunction syndrome. What is the best strategy to begin a discussion of limitation of interventions with the family?

  
  
  
  
  • A.
    

    Ask the family to share their understanding of their son’s current medical condition, as well as their values, hopes, and goals with regard to their son and his care.

    
    
  • B.
    

    Impress upon the family that the severity of the child’s illness and poor overall prognosis do not justify further aggressive life support given the child’s underlying developmental delay.

    
    
  • C.
    

    Inform the family that the patient is not going to live through the night.

    
    
  • D.
    

    Present a list of interventions and ask whether or not the family would like them performed.

  
  

Preferred response: A

Rationale

Discussions of this nature should always begin by allowing the family to articulate their understanding of the child’s current condition, as well as their hopes, values, and goals for their child overall. After the clinician has heard this information, recommendations for or against various interventions can be made as they pertain to the family’s stated goals. Although it is important to ensure that the family understands the severity of illness and poor prognosis, it is not appropriate to make a recommendation against continuing life support based only on the presence of developmental delay. Physicians are poor at predicting the exact time of death for patients, so statements of certainty around death should be avoided. Physicians should avoid presenting families with a “menu” of options for care; rather they should elicit the family’s goals and make recommendations for pursuing or limiting certain interventions based on their stated goals. Physicians must avoid phrases such as “do everything,” as they are nonspecific and imply that “doing” is always the best course of action.

• 4.
  

  Which of the following is true of methadone use for symptom management?

  
  
  
  
  • A.
    

    It has a toxic metabolite that can accumulate and lead to seizures.

    
    
  • B.
    

    It has a long and variable half-life, which can lead to accumulation over time.

    
    
  • C.
    

    It is renally excreted and therefore should be avoided in patients with renal failure.

    
    
  • D.
    

    It shortens the QT interval.

  
  

Preferred response: B

Rationale

The half-life of methadone varies from less than 10 hours to greater than 75 hours, depending on a variety of host factors. It can easily accumulate as it is reaching steady state and lead to oversedation and even obtundation. Therefore dosing and titration must be performed carefully. Morphine is renally excreted and should be avoided in renal failure. Meperidine has a toxic metabolite that can accumulate and lead to seizures. Fentanyl is the only opiate available as a transdermal patch. Methadone prolongs the QT interval, and a screening electrocardiogram should be considered prior to its initiation.

Rationale

Early referral for organ donation to the organ procurement organization (OPO) is considered a best practice and enhances recovery of organs for transplantation. Donor management should be viewed as a continuum of care provided by the pediatric intensivist and the critical care team from the time of admission to recovery of organs for transplantation. Involvement of intensivists results in better donor management and recovery of more organs with better graft function following transplantation. The discussions and decision to authorize organ donation after cardiac death (DCD) should only occur after an independent decision to withdraw medical support has been decided upon by the parents or legal guardian. This firewall avoids the perceived ethical conflict that the patient is being allowed to die to recover organs. Authorization must occur from parents or legal guardians.

• 2.
  

  A 10-month-old unrestrained child who is a victim of a motor vehicle crash is admitted to your PICU. The child has sustained significant intracranial injury with subdural blood noted on the initial computed axial tomography scan of the head. The neurosurgical team has indicated that no surgical intervention is required at this time. This child has a Glasgow Coma Score of 3. No sedation or analgesia has been administered for the past 8 hours. The child is endotracheally intubated and mechanically ventilated with fraction of inspired oxygen (F io ₂ ), 0.8; peak inspiratory pressure, 30 cm H ₂ O; positive end expiratory pressure, 10 cm H ₂ O; ventilator rate, 22 breaths per minute. The chest radiographs show bilateral pulmonary contusions. Agonal respirations noted 24 hours ago have ceased. Blood pressure is being supported with an epinephrine infusion of 0.7 μg/kg/min. Urine output has remained acceptable since admission 2 days ago. The bedside nurse notifies you that the child has fixed and dilated pupils. Which of the following statements is most correct?

  
  
  
  
  • A.
    

    Ancillary studies are not required to make the diagnosis of neurologic death in infants younger than one year of age.

    
    
  • B.
    

    An observation period of 24 hours between neurologic examinations is recommended to determine neurologic death in this patient.

    
    
  • C.
    

    The partial pressure of carbon dioxide (Paco ₂ ) of 59 mm Hg during the apnea exam is sufficient to confirm brain death.

    
    
  • D.
    

    Two separate examinations and a single apnea test are required to determine neurologic death in infants and children.

  
  

Preferred response: A

Rationale

Determination of neurologic death is a clinical diagnosis that relies on the neurologic examination and an apnea test. Neurologic death can be determined in term infant 37 weeks estimated gestational age (EGA) to 30 days of age to 18 years of age. It can be more difficult to make a determination of neurologic death in the neonate and younger child; therefore, serial examinations are essential to ensure the clinical examination remains consistent throughout the observation and testing period. The recommended observation period for infants 37 weeks EGA to 30 days of age is 24 hours. A 12-hour observation period is recommended for children older than 30 days of age. Apnea testing must be performed with each examination, and the Paco ₂ must rise to >60 mm Hg and 20 mm Hg above the baseline Paco ₂ for the apnea test to be valid by current national guidelines. Ancillary studies are not required to make a determination of neurologic death in any patient of any age unless the clinical examination and apnea test cannot be completed, making choice A the correct response.

• 3.
  

  You have been asked by the organ procurement organization to assist with management of a 4-year-old child. This patient has been declared dead by neurologic criteria, and the parents have authorized donation. This patient has required extensive fluid resuscitation for blood pressure support. The child continues to receive vasopressor support with an epinephrine infusion of 0.6 μg/kg/min and dopamine of 12 μg/kg/min. Mechanical ventilation is instituted as follows: fraction of inspired oxygen (F io ₂ ), 0.65; peak inspiratory pressure, 28 cm H ₂ O; positive end expiratory pressure, 12 cm H ₂ O; ventilator rate, 22 breaths per minute. Laboratory evaluation reveals: hemoglobin, 7.6 g/dL; hematocrit, 22.3%; serum sodium, 162 mEq/L; potassium, 3.1 mEq/L; chloride, 119 mEq/L; blood urea nitrogen (BUN), 19 mg/dL; creatinine, 1.2 mg/dL. Which of the following statements is correct?

  
  
  
  
  • A.
    

    Corticosteroids can stabilize lung function and reduce free water accumulation in a donor

    
    
  • B.
    

    Desmopressin for treatment of diabetes insipidus can improve blood pressure and potentially reduce vasopressor requirements in a donor

    
    
  • C.
    

    Intranasal vasopressin is the preferred treatment for diabetes insipidus in a donor

    
    
  • D.
    

    Thyroid hormone prevents the anaerobic to aerobic cellular metabolic shift in a donor

  
  

Preferred response: A

Rationale

Hormonal replacement therapy (HRT) restores aerobic metabolism, replaces hormone derived from the hypothalamus and pituitary, augments blood volume, and minimizes the use of inotropic support while optimizing cardiac output. Common agents used for HRT include thyroid hormone, corticosteroids, and vasopressin or desmopressin for treatment of diabetes insipidus.

Corticosteroids such as hydrocortisone are another pharmacologic agent routinely used by many centers for HRT to assist with hemodynamic support. Treatment of the donor with high doses of corticosteroids reduces inflammation associated with neurologic death and modulates immune function. The potential benefit of hydrocortisone and other steroids may lie in their ability to alter adrenergic receptors and regulate vascular tone by increasing sensitivity to catecholamines. Steroids have also been shown to stabilize pulmonary function, reduce lung water accumulation, and increase lung recovery from donors, making A the correct response.

The effects of thyroid hormone on myocardial contractility can be immediate or delayed. Thyroid hormone is commonly used in the hemodynamically unstable donors. The acute inotropic properties of thyroid hormone may occur as a result of beta-adrenoreceptor sensitization. Additionally, thyroid hormone administration may play an important role in maintaining aerobic metabolism at the tissue level after neurologic death has occurred. Levothyroxine (Synthroid) and triiodothyronine (T3) are the two intravenous thyroid agents available for administration.

Vasopressin is commonly used to treat diabetes insipidus (DI) in the donor. This agent is not as potent as desmopressin on a weight per weight basis. Use of vasopressin for treatment of DI can reduce the need for vasopressor support. Vasopressin and desmopressin should be administered by the intravenous route. Intranasal administration is not recommended because of erratic or no absorption in the brain-dead donor.

• 4.
  

  You are caring for a critically ill 15-month-old patient who was a victim of abusive head trauma admitted to your PICU 5 days ago. This child is comatose with a Glasgow Coma Score of 3, fixed and dilated pupils, and no response to noxious stimulation. The child is mechanically ventilated with the following settings: fraction of inspired oxygen (F io ₂ ), 1.0; peak inspiratory pressure, 32 cm H ₂ O; positive end expiratory pressure, 8 cm H ₂ O. Blood pressure is being supported with an epinephrine infusion of 0.9 μg/kg/min, and 15 mg/kg/min of dopamine. The child has a markedly distended abdomen and has minimal urine output.

  
  
  
  
  • 
    

    A chest radiograph revealed posterior and lateral rib fractures and bilateral pleural effusions with a right upper lobe consolidation.

    
    
  • 
    

    Computed tomography scan of the head revealed bilateral subdural and subarachnoid hemorrhages, diffuse cerebral edema, and effacement of the lateral ventricles.

    
    
  • 
    

    Serum laboratory studies revealed white blood cell count, 10.6 × 103/µL; hemoglobin 7.8 g/dL; hematocrit, 24.2%; sodium, 157 mEq/L; potassium, 4.1 mEq/L; chloride, 116 mEq/L; bicarbonate, 16 mEq/L, blood urea nitrogen, 24 mg/dL; creatinine, 1.92 mg/dL; glucose, 136 mmol/L; lactate, 4.3 mg/dL; alanine aminotransferase, 93 U/L; aspartate aminotransferase,126 U/L; albumin, 2.6 g/dL; protein, 4.1 g/dL; prothrombin time (PT), 15 seconds; international normalized ration (INR), 1.6; activated partial thromboplastin time (aPTT), 62 seconds.

    
    
  • 
    

    Arterial blood gas revealed pH, 7.392; partial pressure of carbon dioxide (Paco ₂ ), 30 mm Hg; partial pressure of oxygen (Pao ₂ ), 83 mm Hg; bicarbonate, 18 mEq/L; base excess, −5 mmol/L.

    
    
  • 
    

    Which of the following statements is correct?

    
    
  • A.
    

    Early referral of the organ procurement organization after neurologic death has been declared can enhance chances for organ recovery.

    
    
  • B.
    

    Maintenance of euvolemia and correction of metabolic derangements will have little effect on graft function and viability of organs for transplantation.

    
    
  • C.
    

    Notifying the medical examiner or coroner’s office prior to death may expedite and facilitate organ donation.

    
    
  • D.
    

    Organ donation is not possible because of multisystem organ dysfunction.

  
  

Preferred response: C

Rationale

Involvement of the pediatric intensivist and critical care team in the management of critically ill and injured children, especially in pediatric donation, where there is a limited and decreasing number of donors improves the quality and number of organs recovered.

Preconceptions about eligibility for donation by the critical care team may not be current or accurate. Donor organ suitability for transplantation is best assessed by the organ procurement organization (OPO). Thresholds for acceptable organ dysfunction can vary according to time of evaluation, transplant program comfort levels, and recipient urgency. In many instances management of the potential organ donor can improve organ function and increase chances of successful organ recovery. Serial echocardiograms may demonstrate donor response to effective medical therapy enabling cardiac recovery for transplantation; a positive blood culture or bacterial meningitis may not preclude organ donation if antibiotic therapy has been administered. Organs from HIV positive donors can be transplanted into HIV-positive recipients, and organs from hepatitis positive donors are now being transplanted with good success.

Successful recovery of organs and the prosecution of the perpetrator may still occur in most cases of child homicide with close cooperation between forensic investigators, treating physicians, the transplant team, and OPO. Early involvement of the medical examiner or coroner prior to determination of death and protocols to facilitate organ recovery in homicide cases may reduce denials for organ donation, making answer C the correct choice. Efforts to reduce the number of medical examiner denials for donation are supported in the position statement by the National Association of Medical Examiners.

Early involvement and timely notification of the OPO prior to determination of death allows a greater amount of time for collaboration to coordinate the donation process. Notification of the OPO after determination of death is considered a late referral and may not allow adequate time for the OPO and critical care team to fully discuss donation opportunities. The OPO can also work closely with the medical examiner or coroner to facilitate donation in cases of homicide. Ensuring OPO engagement early in the course of caring for a critically ill patient allows the intensive care team to better understand the entire donation process and eliminate confusion that may disrupt end-of-life care and the process of donation. Early referral improves authorization rates and can assist families with understanding and coping with end-of-life care issues.

• 5.
  

  Which of the following substances is markedly elevated immediately following brain death:

  
  
  
  
  • A.
    

    Antidiuretic hormone

    
    
  • B.
    

    Catecholamines

    
    
  • C.
    

    Cortisol

    
    
  • D.
    

    Insulin

    
    
  • E.
    

    Thyroid hormone

  
  

Preferred response: B

Rationale

Neurologic death resulting from cerebral ischemia increases circulating cytokines, reduces cortisol production, and precipitates massive catecholamine release. Hemodynamic deterioration associated with neurologic death is initiated by a massive release of catecholamines, commonly referred to as sympathetic, catecholamine, or autonomic storm. The sympathetic storm results in intense but transient hypertension.

The tremendous physiologic derangements associated with neuroendocrine dysfunction require specific interventions to restore normal physiology. Agents such as thyroid hormone, corticosteroids, vasopressin, and insulin are commonly employed during donor management. Hormonal replacement therapy can reduce circulatory instability associated with thyroid and cortisol depletion, especially in situations where significant inotropic support is required.

• 6.
  

  Which of the following metabolic derangements is common following neurologic death?

  
  
  
  
  • A.
    

    Hypercalcemia

    
    
  • B.
    

    Hyperglycemia

    
    
  • C.
    

    Hypermagnesemia

    
    
  • D.
    

    Hypochloremia

    
    
  • E.
    

    Hyponatremia

  
  

Preferred response: B

Rationale

The critical care team should actively manage the potential donor and correct existing physiologic and metabolic derangements that follow neurologic death to preserve the option of organ donation for the family. Metabolic derangements such as iatrogenic hypernatremia from hyperosmolar therapy and hyperglycemia associated with catecholamine release and reduced cerebral metabolism should be corrected. Volume loss from osmotic diuresis associated with hyperglycemia and diabetes insipidus (DI) following neurologic death must be anticipated and addressed to prevent cardiovascular collapse.

Without substrate consumption by the brain, glucose needs are reduced, and the patient is prone to hyperglycemia. As neurologic death occurs, cerebral metabolism is further decreased and co ₂ production falls resulting in a reduction in Paco ₂ . Hypothermia should be anticipated as a result of hypothalamic failure and loss of thermoregulation. Additionally, impaired adrenergic stimulation results in loss of vascular tone with systemic vasodilation and amplified heat losses.

Hypocalcemia occurs commonly secondary to large volume replacement with colloids such as albumin, massive blood transfusions that result in large amounts of citrate reducing free calcium concentrations, and sepsis. Calcium is necessary for myocardial contraction and hypocalcemia can depress cardiac output, affect SVR, and organ perfusion. The use of calcium supplementation should be guided by ionized calcium levels.

• 7.
  

  Evaluation of a 3-year-old child for brain death is being considered. To determine brain death in this child, which of the following is most accurate?

  
  
  
  
  • A.
    

    A longer period of observation in this young child is required because of legal issues.

    
    
  • B.
    

    An ancillary study is required to make the diagnosis of brain death in children.

    
    
  • C.
    

    Ancillary studies such as electroencephalogram, radionuclide cerebral blood flow study, and computed tomography angiography are used in children.

    
    
  • D.
    

    A thorough neurologic examination and apnea test are required to make the diagnosis of brain death.

  
  

Preferred response: D

Rationale

In a child older than 1 year, brain death is a clinical diagnosis and does not require an ancillary study unless the examination and apnea test cannot be completed. A thorough neurologic examination and apnea test that is repeated after a specified observation period is required to determine brain death based on clinical criteria. A longer observation period is currently recommended in infants younger than 30 days and for children younger than 1 year. For children older than 1 year, an observation period of 12 hours is recommended. Ancillary studies such as an electroencephalogram and cerebral blood flow study can be used to assist with the diagnosis of brain death. Computed tomography angiography has not been validated in children and cannot be relied on as a diagnostic ancillary test to determine brain death in children. The apnea test must achieve a Pco ₂ of ≥60 mm Hg to be consistent with brain death.

• 8.
  

  Which statement about neurologic death in infants and children is true?

  
  
  
  
  • A.
    

    Ancillary studies are required to make the diagnosis of neurologic death in infants younger than 1 year of age.

    
    
  • B.
    

    A Paco ₂ of 59 mm Hg in a child with acute lung injury who desaturates 3 minutes into the apnea exam is consistent with brain death.

    
    
  • C.
    

    Neurologic death can be determined in term newborns at 37 weeks’ estimated gestational age.

    
    
  • D.
    

    The revised pediatric brain death guidelines require two separate examinations and a single apnea test to determine neurologic death in infants and children.

  
  
  
  

  Preferred response: C

Rationale

Determination of neurologic death can occur in a term infant at 37 weeks’ estimated gestational age (EGA) to 30 days of age. It can be more difficult to make a determination of neurologic death in the neonate; therefore serial examinations are essential to ensure that the clinical examination remains consistent throughout the observation and testing period. The recommended observation period for infants at 37 weeks’ EGA to 30 days of age is 24 hours. Apnea testing must be performed with each examination, and the Paco ₂ must rise to >60 mm Hg and 20 mm Hg above the baseline Paco ₂ to document apnea.

Two neurologic examinations and apnea tests separated by an observation period are required to establish the diagnosis of neurologic death in the United States. The duration of observation between examinations is based on age. Ancillary studies are not mandatory to make a determination of neurologic death. The physician caring for the child will determine the need for ancillary studies based on history and the ability to complete the clinical examination and apnea testing. If clinical examination and apnea testing cannot be safely completed, an ancillary study should be used to assist with determination of death.

Rationale

Quality of life is defined as an individual’s perception of his or her position in life in relation to the individual’s goals, expectations, standards, and concerns. HRQL is defined as quality of life in which a dimension of personal judgment over one’s health and disease is added, and encompasses the impact of health status on physical, mental, emotional, and social functioning.

• 2.
  

  A group of investigators is designing an interventional trial and planning to utilize health-related quality of life (HRQL) as the primary endpoint. Which of the following protocol elements would optimize assessment for this outcome measure?

  
  
  
  
  • A.
    

    Ascertain baseline medical complexity for chronic comorbid conditions

    
    
  • B.
    

    Conduct paired baseline and follow-up HRQL surveys

    
    
  • C.
    

    Control for duration of intensive care unit stay

    
    
  • D.
    

    Undertake illness severity measures (e.g., PRISM, PIM) of all patient participants

  
  

Preferred response: B

Rationale

Conducting paired HRQL assessments controls for each subject’s baseline status and permits change from baseline (paired) analyses. Semi-quantification of baseline chronic comorbid conditions represents an alternative but less specific approach.

• 3.
  

  Which of the following represents a risk factor for prolonged deterioration of functional status from baseline following pediatric critical illness?

  
  
  
  
  • A.
    

    Duration of stay >28 days

    
    
  • B.
    

    Elective PICU admission

    
    
  • C.
    

    Nononcologic diagnoses

    
    
  • D.
    

    Younger age at PICU admission

  
  

Preferred response: A

Rationale

Longer duration of PICU stay, oncologic diagnoses, older age, and emergent PICU admission are all risk factors for prolonged deterioration of functional status assessed by Pediatric Overall Performance Category.

• 4.
  

  Which of the following adverse events was most commonly documented among a cohort of children surviving critical illness at a median follow-up time of 5 months after PICU discharge?

  
  
  
  
  • A.
    

    Fatigue disorder

    
    
  • B.
    

    Post-traumatic stress disorder

    
    
  • C.
    

    Psychiatric disorders

    
    
  • D.
    

    Sleep disorder

  
  

Preferred response: D

Rationale

One study found that at a median of 5 months after discharge, 20% of PICU survivors were at risk for psychiatric disorders, 34% were at risk for PTSD, 38% were at risk for fatigue disorder, and 80% were at risk for a sleep disorder.

Rationale

Compassion fatigue is broadly defined as reduced capacity and interest in being empathetic for those who are suffering. Although often used interchangeably, burnout consists of three dimensions including depersonalization, emotional exhaustion, and diminished feelings of personal accomplishment. While compassion fatigue may result in burnout, they are not synonymous. Low energy in the workplace, unrelieved stress and tension, and alcohol use may all contribute to or be signs or symptoms of burnout; none is specific to define compassion fatigue.

• 2.
  

  Which of the following factors has been found to be significant in the development of burnout among pediatric critical care physicians?

  
  
  
  
  • A.
    

    Female gender

    
    
  • B.
    

    Older age of a practitioner

    
    
  • C.
    

    Presence of a palliative care consult team

    
    
  • D.
    

    Years in pediatric critical care practice

  
  

Preferred response: A

Rationale

A recent national cross-sectional online survey exploring burnout and psychological distress among over 250 pediatric critical care physicians in the United States found that the risk of any burnout was about two times more in women physicians (odds ratio, 1.97; 95% CI, 1.2–3.4). Association between other personal or practice characteristics and burnout was not evident in the study, while regular physical exercise appeared to be protective.

• 3.
  

  Which of the following measures is considered a successful organizational strategy for mitigating burnout in critical care providers?

  
  
  
  
  • A.
    

    Administering annual staff satisfaction surveys

    
    
  • B.
    

    Increasing helpful pop-up alerts within the EMR

    
    
  • C.
    

    Limiting family visitation hours

    
    
  • D.
    

    Using ethics and palliative care consultations in the ICU

  
  

Preferred response: D

Rationale

The Critical Care Societies Collaborative’s Call to Action to address burnout identified that ethics and palliative care consultations is a successful strategy to mitigate burnout by divesting some of the burden of end-of-life discussions to clinical experts. Additionally, providing healthy food options for clinicians, providing an on-site gymnasium, and offering stress-reduction courses are all considered to be useful for mitigating burnout in critical care providers.

• 4.
  

  What factor most specifically impacts the development of burnout in pediatric critical care providers?

  
  
  
  
  • A.
    

    Dealing with dying children

    
    
  • B.
    

    ICU shift length

    
    
  • C.
    

    Open visitation in the pediatric ICU

    
    
  • D.
    

    Pediatric resident and fellow rotation schedules

  
  

Preferred response: A

Rationale

Dealing with the death of a critically ill pediatric patient has been demonstrated to be a specific factor impacting the development of burnout in pediatric critical care providers compared to general ICU related factors.

Rationale

Ventricular morphology is defined by the atrioventricular (AV) valve it contains; however, the atria are not always related to the same sided AV valve (i.e., AV discordance), making answer A incorrect. Systemic venous return is typically to the right atrium and pulmonary venous return to the left atrium, but not always, making answer B incorrect. Answer D is also incorrect, since pulmonary venous return is typically a feature of the left atrium.

• 2.
  

  Which statement is true regarding the transition from fetal to postnatal circulation?

  
  
  
  
  • A.
    

    Compared to an infant at 6 weeks of age, the infant at birth relies mostly on stroke volume in order to have adequate cardiac output.

    
    
  • B.
    

    The ductus arteriosus is kept open in fetal circulation by a balance between prostaglandin E2 (PGE2) and endothelin-1 (ET-1). After birth, the vasoconstrictive effects of PGE2 become more dominant and the ductus constricts, leading to closure of the ductus within 24 hours to 3 weeks

    
    
  • C.
    

    There is a significant decrease in total body oxygen consumption and cardiac output after birth. Over time, with increased distensibility of the ventricular myocardium, the infant relies less on heart rate to augment cardiac output.

    
    
  • D.
    

    With cord clamping, the baby experiences a rise in systemic vascular resistance (SVR) and a reduction in pulmonary vascular resistance (PVR).

  
  

Preferred response: D

Rationale

During transition to postnatal circulation, there is a rise in SVR and a reduction in PVR, and there is a significant increase in total body oxygen consumption and cardiac output, which initially is heavily reliant on heart rate to increase output until ventricular distensibility improves. Cardiac output in the fetus is determined mainly by heart rate because of a limited capacity to increase stroke volume that results mainly from decreased diastolic distensibility. Consequently, fetal bradycardia is detrimental to blood flow and oxygen delivery. In addition, because at birth approximately 80% of the infant’s hemoglobin is in the form of fetal hemoglobin, the reduced ability of this hemoglobin to unload oxygen at the tissue level compels the infant to have a higher cardiac output than the infant will have 4 to 6 weeks later. Therefore the neonate has limited cardiac output reserve, and the heart has near-maximal contractility. These features make the neonate unusually susceptible to diseases that impair cardiac function.

• 3.
  

  When assessing a child with cardiomyopathy who has left ventricular dilation and moderate mitral regurgitation, the preferred method to evaluate and monitor systolic function via echocardiography is:

  
  
  
  
  • A.
    

    Change in ventricular pressure during isovolemic contraction before the aortic valve opens (dP/dT), taken from a continuous wave Doppler of the mitral regurgitation jet.

    
    
  • B.
    

    M-mode derived TAPSE (tricuspid annular plane systolic excursion).

    
    
  • C.
    

    M-mode generated ejection fraction.

    
    
  • D.
    

    No reliable echocardiographic method is available, and this patient should undergo cardiac MRI for functional assessments.

  
  

Preferred response: A

Rationale

TAPSE (tricuspid annular plane systolic excursion) is used to assess right ventricular systolic function (answer B is incorrect). Although an M-mode generated ejection fraction is a popular and common method used to assess systolic function in children, it is less accurate in the context of mitral regurgitation and left ventricular (LV) dilation (answer C is incorrect). Although cardiac MRI is useful for obtaining accurate chamber volumes and measures of systolic function, echocardiography is more practical and remains an accurate method for noninvasive regular surveillance of ventricular systolic function (answer D is incorrect). In the context of LV dilation and mitral valve regurgitation (MR), dP/dT (rate of pressure change over time during isovolumic contraction) is an accurate method of monitoring ongoing changes in contractility and is relatively unaffected by preload changes. However, the clinician must keep in mind that dP/dT is affected by changes in afterload. Therefore, in the context of heart failure therapy with afterload reducing agents, changes in dP/dT measurements of systolic function will need to be considered in this clinical setting.

• 4.
  

  Which statement is true in the context of reduced left ventricular contractility?

  
  
  
  
  • A.
    

    Due to the steep slope of the ventricular elastance line, small changes in afterload result in large increases in stroke volume and decreases in end diastolic pressure and volume.

    
    
  • B.
    

    In order to eject a normal stroke volume, even in the face of a normal afterload, the ventricle compensates by increasing end diastolic volume.

    
    
  • C.
    

    In order to maintain stroke volume and cardiac output, afterload is increased.

    
    
  • D.
    

    In order to keep ejecting the same stroke volume, preload reserve is maintained during periods of increased afterload.

  
  

Preferred response: B

Rationale

See Figure 136.1 . With decreased LV contractility, the ventricle compensates by increasing end diastolic volume (EDV) in order to maintain a normal stroke volume (answer B is correct). A higher afterload causes even further increases in EDV and EDP, which eventually leads to pulmonary edema (answer C is incorrect). In this setting, the normal preload reserve has already been used to maintain stroke volume (answer D is incorrect). Afterload reduction in this context is useful because a small decrease in afterload results in a large increase in stroke volume and large decrease in end-diastolic volume (EDV) and end-diastolic pressure (EDP). There is a relatively flat slope of the maximal ventricular elastance line, NOT a steep slope. Answer A is incorrect.

• 5.
  

  The main difference in the fetal/neonatal myocardium compared with mature adult myocardium is:

  
  
  
  
  • A.
    

    Complete coupling of β adrenoreceptors to G-proteins

    
    
  • B.
    

    More β adrenoreceptors

    
    
  • C.
    

    More contractile components

    
    
  • D.
    

    Sparse, disorganized, and immature T-tubule and sarcoplasmic reticular system

  
  

Preferred response: D

Rationale

The fetal/neonatal myocardium contains less β adrenoreceptors and less contractile components when compared to the adult myocardium. There is incomplete uncoupling of β adrenoreceptors to G-proteins in the fetal/neonatal myocardium as well. The T-tubule and sarcoplasmic reticular system of the fetal/neonatal myocardium are sparse and disorganized.

• 6.
  

  Except in young infants, the preferential source of energy for myocardial function comes from:

  
  
  
  
  • A.
    

    Glucose

    
    
  • B.
    

    Glycogen

    
    
  • C.
    

    Ketones

    
    
  • D.
    

    Long-chain fatty acids

  
  

Preferred response: C

Rationale

In all except young infants, the preferential source of energy for myocardial function comes from the β-oxidation of long-chain fatty acids. After fatty acids enter the cell, they are activated to fatty acid (or acyl) coenzyme A (CoA) compounds by palmitoyl-CoA synthetase, then linked by carnitine palmitoyl transferase I to carnitine to form acylcarnitines, thus releasing CoA. The acylcarnitines cross the mitochondrial membrane, and at the inner surface of the membrane another enzyme, carnitine palmitoyl transferase II, transfers the fatty acids back to CoA. The fatty acids can now undergo β-oxidation with the production of ATP. These enzymes also help transport acylcarnitine esters of CoA out of the mitochondria. These esters are toxic in high concentrations. Fetuses and neonates have decreased activity of carnitine palmitoyl transferase and palmitoyl-CoA synthetase, so glucose, lactate, and short-chain fatty acids are the preferred myocardial energy substrates at this age.

• 7.
  

  The true statement concerning endothelins is:

  
  
  
  
  • A.
    

    Bosentan is an endothelin agonist.

    
    
  • B.
    

    Endothelins act on ET-A receptor and cause vasodilation.

    
    
  • C.
    

    Endothelins act on ET-B receptor and cause vasoconstriction.

    
    
  • D.
    

    Endothelins cause either vasoconstriction or vasodilation.

  
  

Preferred response: D

Rationale

The vascular endothelium elaborates the endothelins (ET-1, ET-2, ET-3), a family of compounds that are vasoactive, structurally related peptides. ET-1 is the most potent vasoconstrictor known. It also promotes mitogenesis and stimulates the renin-angiotensin-aldosterone system and the release of vasopressin and atrial natriuretic peptide. These peptides act on one of two receptor subtypes: ET(A) and ET(B). ET(A) is located mainly on vascular smooth muscle cells and is responsible for mediating vasoconstriction and cell proliferation. ET(B) is present predominantly on endothelial cells and mediates vasorelaxation, as well as ET-1 clearance. Endothelins cause local vasoconstriction or vasodilation, depending on dose and location in the circulation. Individual endothelins occur in low levels in the plasma, generally below their vasoactive thresholds. This finding suggests they are primarily effective at the local site of release. Even at these levels, however, they may potentiate the effects of other vasoconstrictors such as norepinephrine and serotonin. Endothelin antagonists, such as bosentan, now are being used specifically in the setting of pulmonary arterial hypertension.

• 8.
  

  Regarding the regulation of vasomotor tone:

  
  
  
  
  • A.
    

    Adenosine causes vasoconstriction.

    
    
  • B.
    

    Hypokalemia causes vasodilation.

    
    
  • C.
    

    Hyperkalemia causes vasodilation.

    
    
  • D.
    

    Neuropeptide Y causes vasodilation.

  
  

Preferred response: C

Rationale

Local metabolic regulation of vasomotor tone provides an ideal homeostatic mechanism whereby metabolic demand can directly influence perfusion. Adenosine, which accumulates locally when tissue metabolism is high and tissue oxygenation is marginal, causes pronounced vasodilation in the coronary, striated muscle, splanchnic, and cerebral circulations.

Potassium is released from muscle in response to increased work, ischemia, and hypoxia. Hypokalemia causes vasoconstriction. Hyperkalemia, within the physiological range, causes vasodilation by stimulating KIr channels.

In all organs, sensory and efferent nerve endings contain nonadrenergic, noncholinergic (NANC) peptides, for example, neuropeptide Y, VIP, calcitonin gene-related peptide (CGRP), and substance P. Neuropeptide Y is colocalized and released with norepinephrine, and VIP is colocalized with acetylcholine and released upon stimulation of vagal nerve endings. Most of these peptides except neuropeptide Y are vasodilatory, and they help modulate blood pressure and regional flows.

• 9.
  

  What does the segment “A” denote in the Pressure-Volume loop depicted in Figure 136.2 below?

  
  
  
  
  • A.
    

    Ejection fraction

    
    
  • B.
    

    End diastolic pressure

    
    
  • C.
    

    Ejection time

    
    
  • D.
    

    Stroke volume

  
  

  
  

  
  

  

  
  

Preferred response: D

Rationale

The figure depicts the pressure-volume relationship for a single cardiac cycle. During diastolic filling, volume increases and diastolic pressure rises slightly because of the increase in passive tension. At the end of diastole, isovolumic systole occurs, and ventricular pressure rises with no change in volume. When ventricular pressure exceeds aortic pressure, the aortic valve opens, blood is ejected, and ventricular volume decreases. Ejection ends, and pressure falls to diastolic levels as isovolumic relaxation occurs. The pressure and volume reached at the end of systole are those that would have been attained by the isolated ventricle at that same end-systolic volume. In other words, at a given volume, no higher pressure can be generated. The decrease in volume during ejection is the stroke volume which, divided by the end-diastolic volume, gives the ejection fraction; normally, ejection fraction is greater than 65%.

• 10.
  

  In what situation would the left ventricular (LV) pressure-volume relationship in a previously healthy 12-year-old be expected to change from loop abcd to loop a′b′c′d′ in Figure 136.3 , below?

  
  
  
  
  • A.
    

    Blood transfusion

    
    
  • B.
    

    Hemorrhage

    
    
  • C.
    

    Myocardial contusion

    
    
  • D.
    

    Use of low-dose epinephrine

  
  

  
  

  
  

  

  
  

Preferred response: C

Rationale

Loop abcd represents the pressure-volume relationship in an intact heart. Contraction begins at the end-diastolic pressure and volume of point a. Line ab represents isovolumetric contraction. At point b, the aortic valve opens, since left ventricular (LV) pressure exceeds that in the aorta. Ejection begins at point b and ends at point c. At this point, the aortic pressure is equal to the maximal force produced by the ventricular wall for that specific end-systolic fiber length. Isovolumetric relaxation starts at point c and the aortic valve closes. The ventricular pressure drops (line cd). The mitral valve will open when LV pressure falls below left atrial pressure and blood will flow into the LV.

The difference between lines ab and cd is the stroke volume. Point a represents preload and point b represents afterload.

Loop a′b′c′d′ reflects a decrease in contractility, which could be the result of myocardial contusion. There is a decrease in stroke volume despite a larger end-diastolic volume at a similar level of LV pressure.

Afterload reduction and increase in inotropy (low-dose epinephrine or milrinone) would shift the PV curve to the left and upward.

A blood transfusion increases preload, resulting in an increase in stroke volume (see Figure 136.4 below, loop 2). The contractility has not changed (both end-systolic points are on the same line).

• 11.
  

  At this same level of contractility, what strategies would restore the stroke volume for the patient with myocardial contusion and decreased contractility to his baseline?

  
  
  
  
  • A.
    

    Increase in preload and inotropic support

    
    
  • B.
    

    Increase in preload and vasoconstrictor therapy

    
    
  • C.
    

    Increase in preload and vasodilator therapy

    
    
  • D.
    

    Use of diuretics and inotropic support

  
  

Preferred response: C

Rationale

In patients with decreased myocardial contractility, stroke volume can be restored with either an increase in preload (loop 4) or a decrease in afterload (loop 3) (see Figure 136.5 , below).

• 12.
  

  Loop 1 in Figure 136.6 , below, represents the pressure-volume loop in an intact heart. The correct statement regarding the other loops (2 and 3) is:

  
  
  
  
  • A.
    

    Loop 2 is reflective of a decrease in preload, as would occur with diuretics.

    
    
  • B.
    

    Loop 3 is reflective of a decrease in preload, as would occur with diuretics.

    
    
  • C.
    

    Loop 2 demonstrates the effect of increasing afterload.

    
    
  • D.
    

    Loop 2 demonstrates the effect of decreasing afterload.

  
  

  
  

  
  

  

  
  

Preferred response: C

Rationale

The figure above represents the response of a normal heart to an increase in afterload. Loop 1 represents the normal physiologic pressure-volume loop. Stroke volume is diminished in loop 2 due to an increase in afterload. Loop 3 represents a compensatory response to the increase in afterload. Contraction begins at a higher end-diastolic volume. The heart ejects the same stroke volume at a higher afterload. Even though the stroke volumes for loops 1 and 3 are the same, the ejection fraction is lower for loop 3, since the end-diastolic volume is increased.

Rationale

At any given pressure, the difference between autoregulated and maximal flows is termed coronary flow reserve . Coronary flow reserve indicates how much extra flow the myocardium can get at a given pressure to meet increased demands for oxygen; if reserve is much reduced, then flow cannot increase sufficiently to meet demands and myocardial ischemia will occur. Coronary flow reserve is normally lower in the subendocardium than in the subepicardium, and decreases in coronary flow reserve are always more profound in the subendocardium than in the subepicardium.

If autoregulated flow is normal but maximal flow is decreased, then coronary flow reserve will be reduced. Coronary flow reserve also can be reduced if maximal flows are normal but autoregulated flows increase.

• 2.
  

  Nitric oxide (NO) is a labile humoral factor produced by nitric oxide synthase from l-arginine in the vascular endothelial cell. Which of the following is true of nitric oxide?

  
  
  
  
  • A.
    

    Decreases significantly in the pulmonary vasculature immediately after birth

    
    
  • B.
    

    Is important in basal vascular tone, but less so for dynamic changes in vascular tone

    
    
  • C.
    

    Is increased in response to increases in shear/flow across endothelial cells

    
    
  • D.
    

    Produces vascular smooth muscle cell contraction by increasing the concentration of cGMP via the activation of soluble guanylate cyclase

  
  

Preferred response: C

Rationale

NO is a labile humoral factor produced by NO synthase from L-arginine in the vascular endothelial cell. NO diffuses into the smooth muscle cell and produces vascular relaxation by increasing concentrations of cGMP via the activation of soluble guanylate cyclase. NO is released in response to a variety of factors, including shear stress (flow) and the binding of certain endothelium-dependent vasodilators (such as acetylcholine, adenosine triphosphate [ATP], and bradykinin) to receptors on the endothelial cell. Basal NO release is an important mediator of both resting pulmonary and systemic vascular tone in the fetus, newborn, and adult, as well as a mediator of the fall in pulmonary vascular resistance normally occurring at the time of birth. Dynamic changes in NO release are fundamental to the regulation of all vascular beds.

• 3.
  

  Of the following agents, which has the most potent vasoconstricting properties?

  
  
  
  
  • A.
    

    Angiotensin II

    
    
  • B.
    

    Aldosterone

    
    
  • C.
    

    Endothelin-1

    
    
  • D.
    

    Thromboxane A ₂

  
  

Preferred response: C

Rationale

Endothelin-1 (ET-1) is produced by vascular endothelial cells. It has complex vasoactive properties, the most striking of which is its sustained hypertensive action. ET-1 is the most potent vasoconstricting agent discovered, with a potency 10 times that of angiotensin II.

Humoral regulators of vascular tone include angiotensin, arginine vasopressin, bradykinin, histamine, and serotonin. Of less importance are thyroxine, aldosterone, and antinatriuretic peptide. Angiotensin plays a special role in the homeostasis of blood pressure and is produced in persons with hemorrhagic or hypovolemic shock. It causes generalized vasoconstriction in both systemic and pulmonary circulations, but locally it stimulates the release of vasodilating prostaglandins in lung and kidney.

Bradykinin is a potent pulmonary and systemic vasodilator released locally by the action of the proteolytic enzymes on kallikrein after tissue injury.

Breakdown of phospholipids within vascular endothelial cells results in production of important byproducts of arachidonic acid, including prostacyclin (PGI ₂ ) and thromboxane (TXA ₂ ). PGI ₂ activates adenylate cyclase, resulting in increased cyclic adenosine monophosphate (cAMP) production and subsequent vasodilation, whereas TXA ₂ results in vasoconstriction via phospholipase C signaling.

• 4.
  

  Which of the West zones of the lung are effectively perfused in proportion to their height above the left atrium?

  
  
  
  
  • A.
    

    Zones I and II

    
    
  • B.
    

    Zone II only

    
    
  • C.
    

    Zones I and III

    
    
  • D.
    

    Zone III only

  
  

Preferred response: B

Rationale

The inflow pressure of the pulmonary circulation is low, thus creating a vertical gradation to the distribution of blood flow in the lung. Hydrostatic pressure must be adjusted for vertical height above the left atrium, both at the inflow and at the outflow of every alveolar capillary unit. For example, given a pulmonary artery mean pressure of 20 cm H ₂ O (zeroed at the level of the left atrium), an alveolar capillary unit 12 cm above the left atrium faces an inflow pressure of only 8 cm H ₂ O. A left atrial pressure of 5 cm H ₂ O generates no opposing outflow pressure to an alveolar capillary unit more than 5 cm above the left atrium. Critical closing pressure of postcapillary vessels therefore sets outflow pressure for a unit 10 cm above the left atrium. If intrinsic vascular resistance were identical throughout the lung, flow at any vertical height would be determined by hydrostatic driving pressure (inflow-outflow) and would be greatest at the base and least at the apex of the lung. This phenomenon partitions the lung into three vertical regions, named West zones. Zone I vessels are higher above the left atrium than pulmonary artery pressure and are not perfused by the pulmonary artery. Zone II vessels lie above the height defined by the hydrostatic left atrial pressure but below the height of the pulmonary artery pressure. These units are perfused in proportion to the driving pressure across them, which is approximately pulmonary artery pressure less vertical height (or critical closing pressure, whichever is higher). Zone III vessels lie at a vertical height less than outflow pressure. Driving pressure across these units is independent of height because inflow and outflow pressures are comparably influenced by gravity.

• 5.
  

  In which of the following vascular beds do neural stimuli exert little effect on basal blood flow under physiologic conditions?

  
  
  
  
  • A.
    

    Cerebral

    
    
  • B.
    

    Coronary

    
    
  • C.
    

    Muscular

    
    
  • D.
    

    Pulmonary

  
  

Preferred response: A

Rationale

In marked contrast to other vascular beds, neural stimuli have relatively little effect on basal cerebral blood flow (CBF). Cerebral vessels display extensive perivascular innervations, especially the sympathetic nerves arising from the superior cervical sympathetic ganglia, but the brain is well protected from circulating catecholamines by the blood-brain barrier. Thus many of the vasoactive agents used in the critical care setting (α- and β-adrenergic agonists) have minimal effects on resting cerebral vascular tone. Mild to moderate electrical stimulation, as well as surgical resection of both the sympathetic and parasympathetic nervous system, does not alter cerebral vascular tone under resting conditions. However, vigorous sympathetic stimulation, as occurs with strenuous exercise or hypertension, does result in vasoconstriction of large- and medium-size cerebral vessels. Thus a neurogenic mechanism may not mediate cerebral vascular resistance under normal conditions, but it does provide protection at times of stress.

• 6.
  

  Which of the following substrates can the brain use during periods of starvation?

  
  
  
  
  • A.
    

    Arginine

    
    
  • B.
    

    Glutamine

    
    
  • C.
    

    Glycogen

    
    
  • D.
    

    Ketones

  
  

Preferred response: D

Rationale

At rest, cerebral blood flow is approximately 50 mL/100 g tissue/min. Cerebral oxygen consumption is surprisingly high, averaging 3.2 mL/100 g tissue/min. Glucose is the primary energy substrate, although ketones can be utilized during periods of starvation. The brain has no functional capacity to store energy and thus is completely dependent on a steady supply of O ₂ because up to 92% of its adenosine triphosphate (ATP) production results from the oxidative metabolism of glucose.

• 7.
  

  Which of the following drugs should be used with caution in patients with increased intracranial pressure due to a risk of precipitating herniation?

  
  
  
  
  • A.
    

    Esmolol

    
    
  • B.
    

    Lorazepam

    
    
  • C.
    

    Nitroprusside

    
    
  • D.
    

    Pentobarbital

  
  

Preferred response: C

Rationale

Nitroprusside and other nitric oxide donor compounds can dilate cerebral vessels. This process greatly complicates the management of hypertension in patients with increased intracranial pressure. In such patients, nitroprusside may reduce arterial pressure but raise cerebral blood flow and blood volume, thereby causing herniation.

• 8.
  

  Which of the following mediators has been implicated in the vasospasm following subarachnoid hemorrhage?

  
  
  
  
  • A.
    

    Adenosine

    
    
  • B.
    

    Carbon dioxide

    
    
  • C.
    

    Cyclic AMP (cAMP)

    
    
  • D.
    

    Endothelin-1 (ET-1)

  
  

Preferred response: D

Rationale

Substance P, acetylcholine, oxytocin, ET-1, adenosine diphosphate, ATP, and prostaglandin cause nitric oxide (NO)-dependent cerebral vasodilation. Impaired NO signaling is important in the pathophysiology of subarachnoid hemorrhage in which endothelial dysfunction has been well documented, leading to the important clinical problem of vasospasm.

ET-1 is an important mediator of cerebrovascular tone. Both ETA and ETB receptors have been identified in the cerebral vasculature. ET-1 given in high concentrations constricts cerebral vessels, probably via ETA receptor activation. However, ET-1 given in low concentrations relaxes cerebral vessels via endothelial cell ETB receptor activation, a response that is NO dependent. ET-1 has been identified as an important mediator of vasospasm following subarachnoid hemorrhage. ET-1 levels are increased following subarachnoid hemorrhage. In association with the increase in ET-1 levels are increases in ETA receptor levels, smooth muscle cell ETB receptor levels (which mediate vasoconstriction), and endothelin-converting enzyme activity.

Adenosine leads to cerebral vasodilation through an increase in cAMP and increases more than fivefold with hypoxia. Adenosine is critical in CBF autoregulation.

Carbon dioxide plays a critical role in regulation of CBF. A linear increase in CBF is seen with increasing Paco ₂ , making CO ₂ one of the most potent known cerebral vasodilators. Carbon dioxide exerts its effect via reduction in perivascular pH. Arterial H ⁺ cannot cross the blood-brain barrier, but CO ₂ can easily diffuse into the brain. Perivascular acidosis dilates the cerebral vasculature, whereas alkalosis leads to vasoconstriction.

• 9.
  

  In the normal heart, which of the following regions is more prone to ischemia because of low perfusion pressure?

  
  
  
  
  • A.
    

    Right ventricle subepicardial regions

    
    
  • B.
    

    Right ventricle subendocardial regions

    
    
  • C.
    

    Left ventricle subepicardial regions

    
    
  • D.
    

    Left ventricle subendocardial regions

  
  

Preferred response: D

Rationale

Myocardial perfusion over a cardiac cycle is normally approximately the same per gram of tissue in the outer (subepicardial), mid, and inner (subendocardial) layers of the left ventricle, but the dynamics during the cardiac cycle are complicated. At the end of diastole, when the ventricle is relaxed and tissue pressures are probably less than 10 mm Hg in any layer of the left ventricle, pressures in the intramural arteries are probably similar to each other and to aortic pressure. At the beginning of systole, tissue pressure rises to equal intracavitary pressure in the subendocardium but then falls off linearly across the wall to about 10 mm Hg in the subepicardium. These pressures are for an instant added to those inside the vessels because the vessels’ walls are not rigid, and as a result, intravascular pressures in subendocardial arteries exceed aortic pressures, but aortic pressures are higher than are pressures in subepicardial arteries. These pressure gradients and the greater shortening of subendocardial versus subepicardial muscle fibers during systole compress the subendocardial vessels and squeeze blood out of them both forward into the coronary sinus and backward toward the epicardium. In fact, narrowing of the subendocardial vessels facilitates thickening and shortening of the myocytes. This backflow enters the subepicardial arteries to supply their systolic flow. In systole, some forward flow into the orifices of the coronary arteries does indeed occur, but this forward flow does not perfuse the myocardium; it merely fills the extramyocardial arteries. In fact, there is often reverse flow in the epicardial coronary arteries. In early diastole, blood flows first into the subepicardial vessels that have not been compressed, but it takes longer to refill the narrowed subendocardial vessels. Given enough time and perfusing pressure, all the myocardium will be perfused, but if diastole is too short or perfusion pressure is too low, subendocardial ischemia occurs. Right ventricular myocardium, on the other hand, normally is perfused both in systole and in diastole, because of lower tissue pressures.

• 10.
  

  Based on the graph for pressure-flow relations in the left coronary artery during normal flow and maximal vasodilation, which of the following statements is correct?

  
  
  
  
  • A.
    

    Coronary vascular reserve is independent of perfusion pressure.

    
    
  • B.
    

    For normal maximal flow, flow is uncoupled from metabolism.

    
    
  • C.
    

    For normal autoregulated flow, flow is uncoupled from metabolism.

    
    
  • D.
    

    For normal autoregulated flow, an increase in heart rate will increase maximal flow at any perfusion pressure.

  
  

Preferred response: C

Rationale

Coronary vascular resistance has three components: a basal low resistance in the arrested heart with maximally dilated vessels, an added resistance when vessels have tone, and a phasic resistance added whenever the ventricle contracts. In the beating heart with vessels maximally dilated by a pharmacologic dilator, the second of these resistances is absent. Perfusion of the left ventricular myocardium then produces a steep pressure-flow relation that is linear at higher flows but usually curvilinear at low pressures and flows ( Figure 136.7 ). Because the vessels are maximally dilated, flow is uncoupled from metabolism and depends only on driving pressure and resistance. If heart rate is increased, maximal flow at any perfusion pressure decreases because the heart is in a relaxed state for a smaller proportion of each minute.

If tone is allowed to return to the coronary vessels, then the pressure-flow relationship can be assessed at different perfusion pressures after cannulating the left coronary artery. It is necessary to do this because when cardiac metabolism and blood flow are coupled, increasing aortic blood pressure will increase coronary flow not only by increasing perfusion pressure but also by increasing myocardial oxygen demand. Under normal conditions coronary blood flow is autoregulated, such that if perfusion pressure is raised or lowered from its normal value, there is a range over which almost no change in flow occurs; a rise in pressure has caused vasoconstriction, and a fall in pressure has caused vasodilation. At perfusion pressures above some upper limit, flow increases, probably because the pressure overcomes the constriction. More important, at pressures below about 40 mm Hg (but varying, as discussed later), flow decreases predominantly in the deep subendocardial muscle ( Figure 136.8 ), indicating that some vessels have reached maximal vasodilation and can no longer decrease resistance to compensate for the decreased perfusion pressure. In these vessels, flow and pressure are directly related. If this pressure dependency occurs, then a further decrease in perfusion pressure decreases local blood flow below the required amount, or if myocardial oxygen demands increase at the same low perfusion pressure (as will occur if the ventricle becomes dilated), the requisite increase in flow will not occur. These two conditions cause subendocardial ischemia.

At any given pressure, the difference between autoregulated and maximal flows is termed coronary flow reserve. (Coronary flow reserve can be measured in units of mL/min but also can be assessed by a dimensionless flow reserve ratio derived by dividing maximal flow by resting flow.) Flow reserve depends on perfusion pressure because of the steepness of the pressure-flow relation in maximally dilated vessels. Coronary flow reserve indicates how much extra flow the myocardium can get at a given pressure to meet increased demands for oxygen; if reserve is much reduced, then flow cannot increase sufficiently to meet demands and myocardial ischemia will occur. What the figure does not show is that coronary flow reserve is normally lower in the subendocardium than in the subepicardium and that decreases in coronary flow reserve are always more profound in the subendocardium than in the subepicardium.

• 11.
  

  Regarding coronary artery perfusion, a shift from normal autoregulated flow to increased autoregulated flow may be seen in which of the following conditions?

  
  
  
  
  • A.
    

    Myocardial ischemia

    
    
  • B.
    

    Coronary spasm

    
    
  • C.
    

    Increased blood viscosity

    
    
  • D.
    

    Carbon monoxide poisoning

  
  

Preferred response: D

Rationale

Coronary flow reserve also can be reduced if maximal flows are normal but autoregulated flows increase ( Figure 136.9 ). Increased myocardial flows above normal values can occur with exercise, tachycardia, anemia, carbon monoxide poisoning, leftward shift of the hemoglobin oxygen dissociation curve (as in infants with a high proportion of fetal hemoglobin), hypoxemia, thyrotoxicosis, acute ventricular dilation (because of increased wall stress), inotropic stimulation by catecholamines, and acquired ventricular hypertrophy. If autoregulated flow is normal but maximal flow is decreased, as indicated by the decreased slope of the pressure-flow relation during maximal dilation ( Figure 136.10 ), then coronary flow reserve will be reduced. Such a change can occur with marked tachycardia; a decrease in the number of coronary vessels due to small vessel disease, as in some collagen vascular diseases, especially systemic lupus erythematosus; increased resistance to flow in one or more large coronary vessels because of embolism, thrombosis, atheroma, or spasm; impaired myocardial relaxation due to ischemia; myocardial edema; a marked increase in left ventricular diastolic pressure; marked increase in left ventricular systolic pressure if coronary perfusion pressure is not also increased, as in aortic stenosis or incompetence; and an increase in blood viscosity, most commonly seen with hematocrit levels higher than 65%.

• 12.
  

  Pulmonary embolism and subsequent right ventricular failure develops in a previously normal 17-year-old patient. Which of the following drugs would help restore right ventricular function to normal?

  
  
  
  
  • A.
    

    Dobutamine

    
    
  • B.
    

    Esmolol

    
    
  • C.
    

    Milrinone

    
    
  • D.
    

    Norepinephrine

  
  

Preferred response: D

Rationale

Right ventricular myocardial blood flow is affected by the low right ventricular systolic pressure and the fact that changes in aortic pressure alter coronary perfusion pressure without altering right ventricular pressure work. If the normal right ventricle is acutely distended—for example, by pulmonary embolism—eventually right ventricular failure occurs. The increased wall stress increases oxygen consumption but the raised systolic pressure reduces coronary flow, so when supply cannot match demand, right ventricular myocardial ischemia occurs. Raising aortic perfusing pressure mechanically or with α-adrenergic agonists increases right ventricular myocardial blood flow, relieves ischemia, and restores right ventricular function to normal. Improved coronary flow is not the only mechanism of this improvement; increased left ventricular afterload moves the ventricular septum toward the right ventricle and improves left ventricular performance.

Rationale

Endothelin is an endothelium-derived vasoconstrictor. All other choices are endothelium vasodilators. The vasodilatory action of acetylcholine is derived through NO. Both NO and prostacyclin can be used clinically.

• 2.
  

  Binding of thrombin to cell surface thrombomodulin facilitates activation of which of the following?

  
  
  
  
  • A.
    

    Antithrombin III

    
    
  • B.
    

    Platelets

    
    
  • C.
    

    Protein C

    
    
  • D.
    

    Protein S

  
  

Preferred response: C

Rationale

Thrombin activity is also modulated by endothelial cell synthesis of thrombomodulin. The binding of thrombin to thrombomodulin facilitates the enzyme’s activation of the anticoagulant protein C. Activated protein C (APC) activity is enhanced by cofactor C, also called protein S, which is synthesized by endothelial cells as well as other cells ( Figure 136.11 ). APC inhibits factor Va and factor VIIIa.

APC has a variety of antiinflammatory activities. It suppresses inflammatory cytokine during sepsis, inhibits leukocyte adhesion, decreases leukocyte chemotaxis, reduces endothelial cell apoptosis, helps maintain endothelial cell barrier function through activation of the sphingosine-1 phosphate receptor, and minimizes the decrease in blood pressure associated with severe sepsis.

Another interesting effect of APC is its plasminogen activator inhibitor 1 (PAI-1) neutralizing effect. PAI-1 is a glycoprotein that acts as an acute-phase protein during acute inflammation. Its primary role in vivo is the inhibition of both tissue- and urokinase-type plasminogen activators. PAI-1 is the most efficient inhibitor of APC and thrombin in the absence of heparin. PAI-1 competes with thrombomodulin for binding with thrombin, which, in combination with its inhibition of APC, makes it a strong local procoagulant by a combined action of displacing and inactivating anticoagulant thrombin from thrombomodulin. In this way PAI-1 has important pathophysiologic effects in acute and chronic diseases.

• 3.
  

  Protein C acts by inhibiting the activities of which of the following?

  
  
  
  
  • A.
    

    Factors II and V

    
    
  • B.
    

    Factors II and Xa

    
    
  • C.
    

    Factors Va and VIIIa

    
    
  • D.
    

    Factors VIIa and Xa

  
  

Preferred response: C

Rationale

See Fig. 136.11 .

• 4.
  

  Exposure and binding of endothelial tissue factor to which of the following factors initiates the coagulation cascade, resulting in the formation of fibrin?

  
  
  
  
  • A.
    

    Factor II

    
    
  • B.
    

    Factor Va

    
    
  • C.
    

    Factor VIIa

    
    
  • D.
    

    Factor VIII

  
  

Preferred response: C

Rationale

The expression and release of tissue factor is the pivotal step in transforming the endothelium from an anticoagulant to a procoagulant surface. Tissue factor accelerates factor VIIa–dependent activation of factors X and IX. The synthesis of tissue factor is induced by a number of agonists, including thrombin, endotoxin, several cytokines, shear stress, hypoxia, oxidized lipoproteins, and other endothelial insults. Once endothelial cells expressing tissue factor are exposed to plasma, prothrombinase activity is generated and fibrin is formed on the surface of the cells. Tissue factor also can be found in plasma as a soluble protein. Its role there is not well understood, but it probably plays a role in the initiation of coagulation.

• 5.
  

  Which of the following causes the production of inducible NO synthase (iNOS)?

  
  
  
  
  • A.
    

    Bradykinin

    
    
  • B.
    

    Histamine

    
    
  • C.
    

    Insulin

    
    
  • D.
    

    Tumor necrosis factor-α

  
  

Preferred response: D

Rationale

NO is generated from the conversion of L-arginine to NO and L-citrulline by the enzyme nitric oxide synthase (NOS). Two general forms of NOS exist: constitutive and inducible. In the unstimulated state, NO is continuously produced by constitutive NOS (cNOS). The activity of cNOS is modulated by calcium that is released from endoplasmic stores in response to the activation of certain receptors. Substances such as acetylcholine, bradykinin, histamine, insulin, and substance P stimulate NO production through this mechanism. Similarly, shearing forces acting on the endothelium are another important mechanism regulating the release of NO. The inducible form of NOS is not calcium dependent but instead is stimulated by the actions of cytokines (e.g., tumor necrosis factor-α and interleukins) or bacterial endotoxins (e.g., lipopolysaccharide). Induction of iNOS occurs over several hours and results in NO production that may be more than 1000-fold greater than that produced by cNOS. This mechanism is important in the pathogenesis of inflammation (see Figure 136.12 ).

• 6.
  

  Where is NO produced?

  
  
  
  
  • A.
    

    Endothelial cell

    
    
  • B.
    

    Neutrophils

    
    
  • C.
    

    Platelets

    
    
  • D.
    

    Red blood cell

  
  

Preferred response: A

Rationale

Furchgott and Zawadzki first postulated the existence of an endothelial relaxing factor in 1980, when they noticed that the presence of endothelium was essential for rabbit aortic rings to relax in response to acetylcholine. Later, it was determined that the biological effects of endothelial relaxing factor are mediated by NO. NO is generated in the endothelial cell from the conversion of L-arginine to NO and L-citrulline by the enzyme NOS.

• 7.
  

  NO acts by which of the following mechanisms?

  
  
  
  
  • A.
    

    Binding to cyclic adenosine monophosphate (cAMP)

    
    
  • B.
    

    Binding to cyclic guanosine monophosphate (cGMP)

    
    
  • C.
    

    Binding to adenyl cyclase

    
    
  • D.
    

    Binding to guanylyl cyclase

  
  

Preferred response: D

Rationale

Once NO is formed by an endothelial cell, it readily diffuses out of the cell and into adjacent smooth muscle cells, where it binds to and activates the soluble form of guanylyl cyclase, resulting in the production of cGMP from guanosine triphosphate.

• 8.
  

  Prostacyclin acts by which of the following mechanisms?

  
  
  
  
  • A.
    

    Binding to cAMP

    
    
  • B.
    

    Binding to cGMP

    
    
  • C.
    

    Binding to guanylyl cyclase

    
    
  • D.
    

    Binding to prostacyclin receptors

  
  

Preferred response: D

Rationale

Prostacyclin is a potent vasodilator that is active in both the pulmonary and systemic circulations. In addition to its vasodilatory effects, prostacyclin also has antithrombotic and antiplatelet activity. Its release may be stimulated by bradykinin and adenine nucleotides. Like NO, it is chemically unstable with a short half-life. However, unlike NO, prostacyclin activity in arterial beds depends on its ability to bind to specific receptors in vascular smooth muscle. Its vasodilator activity is therefore determined by the expression of such receptors. Prostacyclin receptors are coupled to adenylate cyclase to elevate cAMP levels in vascular smooth muscle. The increase in cAMP results in (1) stimulation of adenosine triphosphate–sensitive K ⁺ channels, resulting in hyperpolarization of the cell membrane and inhibition of the development of contraction, and (2) increased efflux of Ca ²⁺ from the smooth muscle cell and inhibition of the contractile machinery .

• 9.
  

  Which of the following statements regarding the interaction between nitric oxide (NO) and prostacyclin is correct?

  
  
  
  
  • A.
    

    NO inhibits the action of prostacyclin.

    
    
  • B.
    

    NO and prostacyclin act sequentially to cause vasodilation.

    
    
  • C.
    

    Prostacyclin inhibits the action of NO.

    
    
  • D.
    

    Prostacyclin facilitates the cellular release of NO.

  
  

Preferred response: D

Rationale

Prostacyclin facilitates the release of NO by endothelial cells, and the action of prostacyclin in vascular smooth muscle is potentiated by NO . Interestingly, NO also may potentiate the effects of prostacyclin. The NO-mediated increase in cGMP in smooth muscle cells inhibits a phosphodiesterase that breaks down cAMP, therefore indirectly prolonging the half-life of the second messenger of prostacyclin.

Rationale

Due to cardiopulmonary interactions, when a patient receives a positive pressure breath their right ventricular preload will decrease, an effect accentuated by hypovolemia. The result of this temporary decrease in right ventricular preload is a decrease in left ventricular preload which follows a few cardiac cycles later and manifests itself as a decrease in pulse pressure during insufflation of the lungs due to the decreased blood volume ejected.

A is incorrect as only central venous pressures <5 mm Hg have been reliably shown to predict an increase in cardiac output following a fluid bolus.

C is incorrect because a pulmonary artery occlusion pressure of 12 mm Hg during deep sedation and paralysis is higher than normal suggesting that the left atrium or ventricle is stressed, a condition likely to be worsened by increasing its volume load.

D is incorrect as there is insufficient evidence for manual liver palpation as a surrogate or replacement for passive leg raising, particularly without the explicit inclusion of sedation and paralysis. Liver compression may raise a child’s blood pressure due to pain, discomfort, anxiety, or increased alertness.

• 2.
  

  In a well calibrated, well-functioning arterial line of appropriate size, cannulation of which site will report the largest pulse pressure?

  
  
  
  
  • A.
    

    Axillary artery

    
    
  • B.
    

    Brachial artery

    
    
  • C.
    

    Common femoral artery

    
    
  • D.
    

    Radial artery

  
  

Preferred response: D

Rationale

Since impedance increases in the circulatory system the further a measurement is taken from the heart, the blood pressure increases with distance from the heart while the flow velocity decreases. The effect of this will be to raise the systolic peak while accelerating the diastolic downslope of the pressure reading. Mathematically the area under this curve will remain the same, though the pulse pressure will vary depending on where it is measured, with the highest measurements being those taken most distally to the heart ( Figure 136.13 ).

• 3.
  

  Which patient is most likely to display pulsus alternans on their arterial line tracing?

  
  
  
  
  • A.
    

    An infant newly diagnosed with anomalous left coronary artery from the pulmonary artery (ALCAPA)

    
    
  • B.
    

    A child on noninvasive positive pressure ventilation with community acquired pneumonia

    
    
  • C.
    

    A teenager with primary pulmonary arterial hypertension newly diagnosed with corona virus infection

    
    
  • D.
    

    A child who is postoperative day one from deceased donor renal transplant

  
  

Preferred response: A

Rationale

Pulsus alternans is an arterial line tracing which alternates between weak and strong beats and is associated with left ventricular systolic impairment. The systolic impairment results in an increased end-diastolic volume which leads to an increased stroke volume on the next cardiac cycle. The most likely patient to have left ventricular systolic impairment is the child with ALCAPA due to the deoxygenated blood from the pulmonary artery supplying their left coronary artery.

• 4.
  

  Central venous pressure is most frequently used as a measure of which of the following?

  
  
  
  
  • A.
    

    Left ventricular preload

    
    
  • B.
    

    Left ventricular afterload

    
    
  • C.
    

    Right ventricular preload

    
    
  • D.
    

    Right ventricular afterload

  
  

Preferred response: C

Rationale

The central venous pressure is measured in the right atrium, super vena cava, or inferior vena cava and is the pressure at the end of diastole. Thus it represents the force, or load, on the right ventricle during diastole which is also called preload. Left ventricular preload cannot be measured from the central venous system, nor can the afterload of either ventricle.

• 5.
  

  A 7-day-old male with d -transposition of the great arteries presents 8 hours after an arterial switch operation with a heart rate of 180 beats per minute and hypotension (mean arterial pressure of 35 mm Hg). He appears to have A-V dissociation on telemetry. What would be the most likely pattern seen on the central venous pressure (CVP) monitor?

  
  
  
  
  • A.
    

    Broad, flat a waves

    
    
  • B.
    

    Enlarged a waves

    
    
  • C.
    

    Fused c and v waves

    
    
  • D.
    

    Steep abrupt x and y descent

  
  

Preferred response: B

Rationale

Cannon a waves are enlarged a waves seen when the right atrium is ejecting against a closed tricuspid valve, and they may be seen when atrioventricular discordance occurs (in this case, during an episode of postoperative junctional ectopic tachycardia). They will resolve once the underlying illness is treated. Response C occurs in tricuspid regurgitation, when the backflow of blood out of the right ventricle obliterates the x descent and the c wave becomes accentuated. Response D occurs during pericardial constriction or tamponade physiology. Although the patient is tachycardic and hypotensive, there are no other signs, from the stem, that the patient has this physiology. Response A, or loss of a wave, occurs during atrial fibrillation because loss of atrial contraction results in missing the a wave ( Figure 136.14 ).

• 6.
  

  An otherwise healthy infant has a peripheral arterial line placed in his dorsalis pedis for monitoring during an elective surgery. What discrepancy is likely to be found between a cuff blood pressure on the arm and the readings assessed from the arterial line?

  
  
  
  
  • A.
    

    The mean arterial pressure (MAP) measurements will be widely different.

    
    
  • B.
    

    The systolic blood pressure (SBP) measurement will be lower on the intraarterial measurement.

    
    
  • C.
    

    The diastolic blood pressure (DBP) measurement will be lower on the intraarterial measurement.

    
    
  • D.
    

    The MAPs will be the same, but the SBP on the cuff pressure will be higher.

  
  

Preferred response: C

Rationale

This is referred to as distal pulse amplification and occurs due to the nature of the vascular tree; the systolic blood pressure increases, and diastolic blood pressure decreases as you move peripherally, with a more exaggerated pulse pressure. The MAPs remain the same between the peripheral and central sites. Pressure waveform measurements from different sites of the arterial tree have varying morphologies depending on the properties of the vascular bed. The changes that occur as you move peripherally have to do with alterations in impedance and harmonic resonance.

• 7.
  

  A 10-year-old child has been admitted to the intensive care unit (ICU) in shock. The child is endotracheally intubated, mechanically ventilated, and has a pulmonary artery catheter in place. The following information is available:

  
  
  
  
  • •
    

    Heart rate: 140 beats/min

    
    
  • •
    

    Blood pressure: 90/60 mm Hg

    
    
  • •
    

    Central venous pressure (CVP): 10 mm Hg

    
    
  • •
    

    Mean arterial pressure (MAP): 70 mm Hg

    
    
  • •
    

    Pulmonary arterial pressure: 45/25 mm Hg

    
    
  • •
    

    Mean pulmonary arterial pressure: 32 mm Hg

    
    
  • •
    

    Venous oxygen saturation: 65%

    
    
  • •
    

    Pulmonary artery occlusion pressure: 15 mm Hg

    
    
  • •
    

    Carbon monoxide (CO): 3 L/min

    
    
  • 
    

    What is the calculated systemic vascular resistance (SVR)?

    
    
  • A.
    

    1600 dynes sec/cm ⁵

    
    
  • B.
    

    30 Woods units

    
    
  • C.
    

    1200 dynes sec/cm ⁵

    
    
  • D.
    

    1200 mm Hg/m ²

  
  

Preferred response: A

Rationale

SVR is calculated by (MAP − CVP)/CO = (70 − 10)/3 = 60/3 = 20 in Woods units. Woods units are converted to dynes sec/cm ⁵ by a multiplicative factor of 80. Thus 20 × 80 = 1600 dynes sec/cm ⁵ .

• 8.
  

  A 3-year-old child is brought to the emergency department with fever and increasing lethargy during the past 24 hours. On initial evaluation the child is minimally responsive and has poor distal perfusion with cool hands and feet. Blood pressure is 70/30 mm Hg, and oxygen saturation is 85% in room air. The child is intubated, central venous access is obtained, and intravenous fluids are administered. An established goal of continued resuscitation for this child is which of the following?

  
  
  
  
  • A.
    

    Achieve a pulmonary artery occlusion pressure of greater than 15 mm Hg

    
    
  • B.
    

    Achieve a central venous pressure (CVP) of 15 mm Hg or higher

    
    
  • C.
    

    Achieve a mixed venous saturation of 70% or higher

    
    
  • D.
    

    Achieve a mean arterial pressure (MAP) of 80 mm Hg or higher

  
  

Preferred response: C

Rationale

Achieving a mixed venous saturation of 70% or higher is one of the goals of early goal-directed therapy for persons with septic shock. Early goal-directed therapy has been shown to decrease mortality in persons with septic shock.

Rationale

While both infants have identical vital signs and are on the same vasoactive infusions, infant B has received a higher “quantity of therapy” (QOT) due to the volume infusions in the last 4 hours to maintain the hemodynamics listed. In addition, infant B has a rising lactate and a lower mixed venous saturation (higher arteriovenous oxygen difference) which may signify inadequate oxygen delivery. Infant B should be carefully monitored, and additional investigations into the cause for the higher QOT should be considered.

• 2.
  

  A 6-month-old infant with tetralogy of Fallot is recovering in the intensive care unit after a complete surgical repair. Approximately 6 hours after the operation is completed, the central venous pressure (CVP) is 15 mm Hg. The patient is hypotensive and receives 10 mL/kg of crystalloid. Which of the following is the least likely to be observed in the physiology described?

  
  
  
  
  • A.
    

    Fluid accumulation in the thoracic and abdominal cavities

    
    
  • B.
    

    Increased chest wall stiffness

    
    
  • C.
    

    Increased intrathoracic pressures

    
    
  • D.
    

    Increased peripheral and pulmonary edema

    
    
  • E.
    

    Increased venous return

  
  

Preferred response: E

Rationale

The patient described in this question with tetralogy of Fallot is likely to have significant right ventricular diastolic dysfunction resulting in high filling pressures (high CVP). Leaky vasculature as a result of inflammation due to cardiopulmonary bypass can result in significant third-spacing of fluid. A fluid bolus for hypotension causes increased tissue edema and fluid accumulation in the thoracic and abdominal cavities which results in increased chest wall stiffness and increased intrathoracic pressure. As a result, there is decreased venous return and therefore decreased preload to the right ventricle which results in further hypotension and diminished cardiac output.

• 3.
  

  An infant with hypoplastic left heart syndrome is recovering after a Norwood Stage I procedure with a modified Blalock-Taussig shunt. The patient’s arterial oxygen saturation and mean arterial blood pressure are within normal limits. The infant has a lactate level that has been rising over the last 4 hours and a wide arteriovenous O ₂ (AVO ₂ ) saturation difference. Which of the following will not increase systemic oxygen delivery in this patient?

  
  
  
  
  • A.
    

    Addition of inhaled nitric oxide to improve pulmonary blood flow

    
    
  • B.
    

    Afterload reduction

    
    
  • C.
    

    Blood transfusion

    
    
  • D.
    

    Increased inotropic support with dobutamine

    
    
  • E.
    

    Sedation and paralysis

  
  

Preferred response: A

Rationale

This patient with single ventricle physiology has complete mixing of systemic and pulmonary venous blood. The rising lactate, minimal urine output, and widened AVO ₂ difference suggested compromised oxygen delivery despite a normal oxygen saturation and mean arterial blood pressure. The addition of a pulmonary vasodilator to improve pulmonary blood flow would likely exacerbate the problem further by increasing pulmonary blood flow at the expense of systemic blood flow. In other words, the Qp:Qs ratio would increase. All of the other options would increase systemic oxygen delivery by improving Qs (options B and D), decreasing systemic oxygen demand (option E), or increasing oxygen carrying capacity and likely mixed venous saturation (option C).

• 4.
  

  A 12-year-old girl is diagnosed with viral myocarditis and has an echocardiogram showing severely depressed biventricular systolic function. Her blood pressure as measured by invasive monitoring is normal for age. Which of the following factors is compatible with a relatively low quantity of therapy?

  
  
  
  
  • A.
    

    A central venous pressure of 6 mm Hg

    
    
  • B.
    

    A lidocaine infusion to suppress ventricular tachycardia

    
    
  • C.
    

    An epinephrine infusion

    
    
  • D.
    

    Need for mechanical ventilation

    
    
  • E.
    

    Two sodium bicarbonate boluses due to metabolic acidosis

  
  

Preferred response: A

Rationale

The patient is presenting with decreased systolic ventricular function in the setting of viral myocarditis. The cardiac output is low; however, the patient’s blood pressure is normal due to the compensatory rise in systemic vascular resistance (SVR). As a result of these factors, one would expect that the patient might require increased filling pressures, a need of inotropic support, and/or mechanical ventilation to provide positive pressure ventilation to decrease oxygen demands and decrease left ventricular afterload. In addition, a patient with myocarditis is at risk of ventricular arrhythmias due to the irritable myocardium. The presence of a metabolic acidosis can also signify poor systemic oxygen delivery. In this particular case, the presence of a low central venous pressure would be reassuring that the patient has not required fluid resuscitation and therefore a significant quantity of therapy. All of the other options would signify a patient that is more critically ill. In this scenario, it would be important to consider advanced therapies such as mechanical circulatory support if there are markers of poor oxygen delivery despite the interventions listed above.

• 5.
  

  What is a primary determinant of systemic oxygen delivery (Do ₂ )?

  
  
  
  
  • A.
    

    Hemoglobin concentration

    
    
  • B.
    

    Intrathoracic pressure

    
    
  • C.
    

    Oxygen consumption

    
    
  • D.
    

    Pulmonary venous oxygen content

  
  

Preferred response: A

Rationale

Do ₂ = Cardiac output (CO) × arterial content of oxygen (Cao ₂ ), where Cao ₂ = (Sao ₂ × Hgb × 1.36) + (Pao ₂ × 0.0031). Therefore because hemoglobin concentration is a key variable that determines systemic arterial O ₂ content, it also is a primary determinant of Do ₂ .

• 6.
  

  A 3-year-old child with hypoplastic left heart syndrome returns from the operating room following a lateral tunnel fenestrated Fontan procedure. The initial postoperative arterial blood gas shows an oxygen saturation of 80% on a F io ₂ 1.0 via the mechanical ventilator. Postoperative chest x-ray is unremarkable, and the echocardiogram shows good right ventricular systolic function, a patent 3-mm fenestration with right-to-left shunting, trace tricuspid regurgitation, no systemic outflow tract obstruction, and an unobstructed Fontan pathway with good flow to both pulmonary arteries. The patient is mildly hypotensive in sinus rhythm with a hemoglobin level of 15 gm/dL and no postoperative bleeding. What is the most appropriate initial management to improve blood pressure and oxygenation?

  
  
  
  
  • A.
    

    Cool the patient to decrease oxygen consumption.

    
    
  • B.
    

    Remove the patient from positive pressure mechanical ventilation.

    
    
  • C.
    

    Start an inotropic agent to improve myocardial contractility.

    
    
  • D.
    

    Transfuse with red blood cells to increase hemoglobin.

  
  

Preferred response: B

Rationale

Positive pressure mechanical ventilation decreases systemic venous return and increases pulmonary vascular resistance, both of which are detrimental to Fontan physiology. Spontaneous respiration with negative intrathoracic pressure will provide the optimal conditions for systemic venous return and decreased pulmonary vascular resistance resulting in improved pulmonary blood flow (oxygenation), preload, and cardiac output.

• 7.
  

  A 3-year-old girl with history of a large ventriculoseptal defect is admitted to your pediatric intensive care unit after ventriculoseptal defect closure. A chest radiograph shows that the cardiothoracic ratio is 0.4. The cardiac apex is displaced upward. What is the most likely reason for these radiographic changes?

  
  
  
  
  • A.
    

    Large pericardial effusion

    
    
  • B.
    

    Left ventricular (LV) enlargement

    
    
  • C.
    

    Patent foramen ovale

    
    
  • D.
    

    Right ventricular (RV) enlargement

  
  

Preferred response: D

Rationale

The cardiothoracic ratio gives a quantitative estimate of cardiac size, which is obtained by dividing the transverse measurement of the cardiac shadow in the posteroanterior view by the width of the thoracic cavity. Cardiomegaly is present if this value is greater than 0.5 in adults and 0.6 in infants. Although useful for assessing LV enlargement, the cardiothoracic ratio is not as sensitive to RV enlargement. RV enlargement results in lateral and upward displacement of the cardiac apex on the posteroanterior view and filling of the retrosternal space on the lateral view. It is perhaps more important to know what the chest x-ray may not reveal: significant cardiac problems, such as constrictive pericarditis, acute fulminant myocarditis, and even acute pericardial tamponade are often associated with a normal-sized heart on a chest radiograph.

• 8.
  

  A 1-year-old patient has a hemoglobin of 9 mg/dL and arterial oxygen saturation of 86%. The child’s arterial blood gas results reveal the following values: pH, 7.38; pco ₂ , 53 mm Hg; and Pao ₂ , 56 mm Hg. Cardiac output is estimated to be 3.2 L/minute. The child’s weight is 10 kg. What is the approximate quantity of oxygen delivered to the tissues in 1 minute (Do ₂ )?

  
  
  
  
  • A.
    

    10 mL O ₂ /kg/min

    
    
  • B.
    

    20 mL O ₂ /kg/min

    
    
  • C.
    

    30 mL O ₂ /kg/min

    
    
  • D.
    

    40 mL O ₂ /kg/min

  
  

Preferred response: C

Rationale

Tissue oxygenation is directly related to both Do ₂ and systemic arterial blood pressure. Do ₂ , the quantity of O ₂ delivered to the tissues per minute, is the product of systemic blood flow (SBF), which equals cardiac output except in patients with certain cardiac malformations, and arterial O ₂ content:

where CO = cardiac output or SBF in L/min or L/min/m ² and CaO ₂ = quantity of O ₂ bound to hemoglobin plus the quantity of O ₂ dissolved in the plasma in arterial blood. The O ₂ content of arterial blood (mL O ₂ /dL blood) equals:

where Sao ₂ = arterial O ₂ saturation, Hgb = hemoglobin concentration (g/dL), 1.36 (constant) = amount of O ₂ bound per gram of hemoglobin (mL) at 1 atmosphere of pressure, Pao ₂ = arterial partial pressure of O ₂ , and 0.003 (constant) = amount of O ₂ dissolved in plasma at 1 atmosphere. The quantity of dissolved O ₂ is generally considered to be negligible in the normal range of Pao ₂ .

In this case, the Cao ₂ is (9 × 1.36 × 0.86) + (0.0031 × 56) = 10.53 + 0.17 = 10.7 mL O ₂ /100 mL. The Do ₂ is therefore 10 × 3.2 × 10.7 = 342.4 mL O ₂ /min or 34.24 mL O ₂ /k.

Rationale

The patient is presenting in cardiogenic shock requiring increase in cardiac output that can be obtained by epinephrine use due to its B1 effects on contractility which should lower the heart rate and increase blood pressure without increasing systemic vascular resistance.

• 2.
  

  The above child arrives in the PICU endotracheally intubated with two peripheral large bore IVs infusing the treatment you recommended above, and has the following vital signs: temperature, 38°C (after IV acetaminophen); heart rate, 120 beats per minute; respirations, 25 per minute (intubated on ventilator with F io ₂ of 0.50); blood pressure, 95/50 mm Hg; Spo ₂ , 98%. You immediately perform a point-of-care ultrasound (POCUS) of the heart from the apical four chamber view which reveals no tamponade but a left ventricular ejection fraction of 25% and normal proximal coronary arteries. An arterial blood gas is obtained revealing: pH 7.20; pco ₂ , 35 mm Hg; po ₂ , 90 mm Hg; base excess, −9.0 mmol/L; lactate level, 8.2 mmol/L (normal: 1-2); B type natriuretic peptide level, 4675 pg/mL (normal: <100 pg/mL). The complete blood count is normal. The child has a positive nasal rapid antigen test for SARS-CoV-2.

  
  
  
  
  • 
    

    Over the next 4 hours the child progresses downward with a worsening metabolic acidosis, increasing lactate level (12.4 mmol/L), lower mixed venous saturation level (<40%); anuria and decreased central and peripheral pulses. A discussion with your pediatric cardiac surgeon and interventional cardiologist leads to the need for mechanical circulatory support for this child. The best device choice for this child is:

    
    
  • A.
    

    Percutaneously inserted Abiomed Impella 2.5 through the right femoral artery

    
    
  • B.
    

    Thoratec Pediamag Right Ventricular Assist Device (RVAD)

    
    
  • C.
    

    Veno-venous extracorporeal life support (VV-ECLS) with a double lumen catheter in the right internal jugular vein

    
    
  • D.
    

    Veno-arterial extracorporeal life support (VA-ECLS) through the right internal jugular vein and carotid artery

  
  

Preferred response: D

Rationale

Only VA ECMO will provide increased systemic cardiac output (Qs) in this patient with cardiogenic shock. Theoretically, the Impella heart pump could provide LV assist in older adolescent but not in a 5-year-old.

• 3.
  

  The child stabilizes on the mechanical circulatory support you chose above but unfortunately after 10 days of aggressive therapy there is no recovery of cardiac function but all other organ function including neurologic status are intact. Your next BEST OPTION for this child’s long term survival is to:

  
  
  
  
  • A.
    

    Continue on the current therapy for an additional 2 weeks hoping for cardiac recovery

    
    
  • B.
    

    Continue on the current therapy but contact the heart transplant team to begin the process of listing the child status 1A

    
    
  • C.
    

    Convert the child over to a paracorporeal Berlin Heart Excor Biventricular Assist Device using two 25-mL pumps as a bridge to cardiac transplant

    
    
  • D.
    

    Speak to the family about the futility in continuing aggressive care and discontinue MCS

  
  

Preferred response: C

Rationale

VA ECMO has stabilized the child with preservation of the child’s other vital organs but this therapy is limited to short term use (despite a few outliers). For the child to be listed and receive a heart transplant, continued support would likely run months. Transitioning the child to a long term VAD is the best option for long term survival (to recovery or transplant). At this time ECLS/VAD are not futile or experimental therapies for this 5-year-old child.

• 4.
  

  A previously well 8-kg, 6-month-old girl is referred from an outside hospital with frequent episodes of new-onset polymorphic ventricular tachycardia. She has been cardioverted several times and commenced on a lidocaine infusion. The episodes are becoming more frequent and associated with significant hypotension. Echocardiogram reveals extensive left ventricular noncompaction with an ejection fraction of 31%. No intracardiac thrombus is reported. A venous saturation of 51% is obtained from an existing right internal jugular central venous catheter. What would be the appropriate subsequent management?

  
  
  
  
  • A.
    

    Cannulate for venoarterial (VA) extracorporeal membrane oxygenation (ECMO) until arrhythmia control is achieved.

    
    
  • B.
    

    Maximize antiarrhythmic medication and initiate anticoagulation and milrinone infusion.

    
    
  • C.
    

    Place a left ventricular assist device (LVAD).

    
    
  • D.
    

    Place on VA ECMO as a bridge to longer-term biventricular assist and heart transplantation.

  
  

Preferred response: D

Rationale

Refractory ventricular tachycardia with clinically significant hemodynamic compromise would necessitate biventricular support. The patient has impaired ventricular function with evidence of inadequate tissue oxygen delivery. The underlying disease process is not amenable to medical therapy alone, and the anticipated duration of mechanical support prior to orthotopic heart transplant would be in the order of weeks to months.

• 5.
  

  A 7-year-old, 22-kg boy is referred to the cardiology clinic with a 5-month history of increasing fatigue, exercise intolerance, anorexia, and dyspnea. His parents comment that his color is gray on minimal exertion. Echocardiography reveals a thin-walled, severely dilated left ventricle with an ejection fraction of 20%. There is moderate mitral regurgitation with an otherwise structurally normal heart and vasculature. A diagnosis of idiopathic dilated cardiomyopathy is made. He is admitted, a central line is placed, and he is started on a milrinone infusion and diuretics. He subsequently develops intermittent unifocal ventricular ectopy. After 24 hours, his parents comment on the improvement in his color, energy levels, and appetite. Listing for heart transplantation is considered. Venous oxygen saturation from his central line is initially 63%. Options for subsequent management include which of the following?

  
  
  
  
  • A.
    

    Discharge to home on milrinone with regular visits with the cardiologist.

    
    
  • B.
    

    Place on left ventricular assist device (LVAD) as a bridge to transplant.

    
    
  • C.
    

    Remain in the PICU with current regimen until a donor heart is available.

    
    
  • D.
    

    Wait for evidence of end-organ dysfunction or worsening symptoms of heart failure before intervening.

  
  

Preferred response: A

Rationale

This is a case of a different disease process in an older child where potential clinical improvement can occur in more than 50% of patients. Management will depend on response to initial therapy. Failure to improve clinically in association with evidence of inadequate tissue oxygen delivery will determine the timing of institution of mechanical support. The child’s size and expected duration of support precludes an adult VAD system or implantation of a short-term device.

• 6.
  

  You are caring for a newborn who underwent an arterial switch operation for d -transposition of the great vessels. Eight hours after surgery, his vital signs are as follows: temperature, 37.8°C; heart rate, 165 beats per minute (sinus rhythm); left atrial pressure, 12 cm H ₂ O; central venous pressure, 15 cm H ₂ O; and blood pressure, 54/31 mm Hg. On physical examination, he has slightly cold extremities and pulses are 1+, breath sounds are clear bilaterally, the abdomen is soft, and the liver edge is palpated 3 cm below the right costal margin. Urine output has been 0.49 mL/kg/h for the past 4 hours. Arterial blood gas values show the following: pH, 7.23; pco ₂ , 37 mm Hg; Pao ₂ , 65 mm Hg; base deficit, 6; and lactic acid, 3.7 mmol/L. Which of the following interventions would potentially be detrimental to this patient?

  
  
  
  
  • A.
    

    Dopamine, 10 µg/kg/min

    
    
  • B.
    

    Epinephrine, 0.03 µg/kg/min

    
    
  • C.
    

    Fentanyl, 3 µg/kg/h

    
    
  • D.
    

    Milrinone, 0.5 µg/kg/min

  
  

Preferred response: A

Rationale

Low cardiac output state (LCOS) is commonly seen after cardiopulmonary bypass and is manifested by oliguria, followed by decreased perfusion, progressive acidosis, and hemodynamic compromise. The goal in management of LCOS is to provide adequate oxygen delivery (Do ₂ ) to the tissues, which can be achieved by decreasing oxygen consumption or increasing Do ₂ . Maintaining normothermia or mild hypothermia, providing adequate analgesia and sedation, and sometimes neuromuscular blockade are common interventions that will help decreased oxygen consumption.

Phosphodiesterase III inhibitors like milrinone are indicated in the postoperative management of LCOS. Milrinone favors calcium transport into the cell by increasing intracellular cyclic adenosine monophosphate. The increased intracellular calcium enhances the contractile state of the myocyte. Milrinone decreases systemic and pulmonary vascular resistance and improves diastolic relaxation by increasing the rate of calcium reuptake after systole. Although low-dose catecholamines are useful in improving contractility (via their β ₁ -adrenergic effect), high-dose catecholamines (dopamine >5 µg/kg/min, epinephrine >0.05 µg/kg/min) will increase heart rate and increase systemic vascular resistance, leading to increased myocardial oxygen consumption, decreased cardiac output, and decreased Do ₂ . If optimized medical management is unsuccessful in reverting LCOS, mechanical support would be indicated.

Rationale

Echocardiography is useful (and the modality of choice) in the evaluation of the cyanotic patient, can often be quickly and easily obtained, and gives immediate answers on residual shunts in the postoperative patient. Prior to taking the infant back for revision of the operation, or to the catheterization laboratory for intervention, it is useful to understand the etiology of the cyanosis. An atrial level communication is at times left intentionally to allow a “pop-off” for the stiff right ventricle in the immediate postoperative period. A chest x-ray would be obtained prior to repositioning the ETT rather than assuming malposition in the setting of equal breath sounds. Increasing the F io ₂ to 100% is not a long-term solution.

• 2.
  

  Which of the following statements is true regarding echocardiography?

  
  
  
  
  • A.
    

    Echocardiography is limited to available acoustic windows.

    
    
  • B.
    

    Echocardiography is uniquely a noninvasive modality.

    
    
  • C.
    

    Echocardiography provides precise measurements of pulmonary arterial pressures.

    
    
  • D.
    

    Echocardiography can provide histologic evaluation of cardiovascular tissues.

  
  

Preferred response: A

Rationale

Echocardiography is limited to the “windows” where the ultrasound beam can penetrate adequately to produce images. It does not penetrate well through air. This can be a major limitation to echocardiography. The remaining statements are not true. Transesophageal (TEE) and intracardiac echo (ICE) are examples of invasive echocardiography. Echocardiography provides estimates of pulmonary arterial pressures, which can be inaccurate for many different reasons.

• 3.
  

  What is the earliest gestational age that cardiac echocardiography can be used to assess fetal cardiac anatomy reliably?

  
  
  
  
  • A.
    

    8 weeks

    
    
  • B.
    

    14 weeks

    
    
  • C.
    

    20 weeks

    
    
  • D.
    

    28 weeks

  
  

Preferred response: C

Rationale

Complete anatomic and physiologic assessment can be obtained in the neonate and in the fetus at 20 weeks of gestation.

• 4.
  

  Which of the following is the mainstay of the anatomic diagnosis of congenital heart disease?

  
  
  
  
  • A.
    

    Angiography

    
    
  • B.
    

    Cardiac catheterization

    
    
  • C.
    

    Computerized tomographic angiography

    
    
  • D.
    

    Echocardiography

  
  

Preferred response: D

Rationale

The technique of echocardiography and the practice of echocardiology have changed the practice of pediatric cardiology by largely replacing the use of cardiac catheterization/angiography for the diagnosis of congenital malformations. Combined with the use of prostaglandin for maintaining the patency of the ductus arteriosus, echocardiography has dramatically reduced the need for emergency cardiac catheterization in neonates. Most patients with congenital heart disease that is detected in the neonatal period can undergo palliative surgery without cardiac catheterization. Most definitive surgical repairs can be performed successfully without the risk of invasive studies. Pulsed, continuous-wave, color, and tissue Doppler have added important capabilities for anatomic and functional assessment. Intraoperative and postoperative management of congenital heart defects has been aided by the addition of transesophageal echocardiography.

• 5.
  

  Right ventricular pressure can be estimated with the use of echocardiography by the simplified Bernoulli equation, where v is peak velocity of which insufficiency jet?

  
  
  
  
  • A.
    

    Pulmonary insufficiency jet 4 v

    
    
  • B.
    

    Pulmonary insufficiency jet 2 v

    
    
  • C.
    

    Tricuspid insufficiency jet 4 v ²

    
    
  • D.
    

    Tricuspid insufficiency jet 2 v ²

  
  

Preferred response: C

Rationale

Estimation of right ventricular systolic pressure by Doppler echocardiography is done with use of the maximum velocity ( v ) of the regurgitant tricuspid jet. The systolic pressure gradient (delta P) between the right ventricle and the right atrium is calculated by using the simplified Bernoulli equation (delta P = 4 v ² ).

• 6.
  

  Segmental analysis of cardiac disease is classically based on which of the following?

  
  
  
  
  • A.
    

    Great vessel arrangement, ventricular looping, situs

    
    
  • B.
    

    Situs, great vessel arrangement, ventricular looping

    
    
  • C.
    

    Situs, ventricular looping, great vessel arrangement

    
    
  • D.
    

    Ventricular looping, great vessel arrangement, situs

  
  

Preferred response: C

Rationale

Comprehensive analysis of cardiovascular anatomy requires a step-by-step segmental approach. A complete step-by-step approach to cardiac diagnosis includes the diagnosis of atrial situs; identification of the chambers and their interconnections; and systematic assessment of valves, septa, coronaries, systemic and pulmonary veins, and aortic anatomy. Imaging of the thymus and diaphragm is part of the detailed echocardiographic examination.

The segmental approach is based on the principle that all aspects of abnormal cardiovascular morphology can be broken down into discrete, mutually exclusive descriptors, allowing unambiguous delineation of any complex congenital malformation. The schema must include information on the presence, position, and connection of each cardiac segment. Classically, three segments have been recognized: atria, ventricles, and great arteries. By describing the anatomic segments and indicating the normality or abnormality of each, a complete description of the cardiac anatomy is possible. It now is possible to code cardiac anatomic abnormalities by segmental analysis.

Determination of cardiac position and atrial-visceral situs is a standard portion of the echocardiographic assessment of congenital heart disease and is the foundation of the segmental approach. Atrial situs and atrial morphology are diagnosed together, and four possibilities exist: solitus (normal), inversus, and heterotaxy that may be right atrial isomerism or left atrial isomerism.

Description of the connection of the atria and ventricles (i.e., AV connection) requires knowledge of both atrial and ventricular morphology. Four patterns of AV connection exist: concordant (i.e., normal); discordant; univentricular through a single inlet (i.e., tricuspid or mitral atresia), double inlet, or common inlet; and ambiguous (i.e., two ventricles with atrial isomerism). When the morphologic right atrium connects normally to the morphologic right ventricle and the left atrium connects to the left ventricle, AV concordance is present. When this connection is reversed and the morphologic right atrium connects to the morphologic left ventricle, AV connection is discordant and sometimes is referred to as ventricular inversion.

Ventriculoarterial connection is the manner in which the great arteries and semilunar valves connect to the ventricular outflow tracts. Normally, the morphologic right ventricle connects to the pulmonary valve and the morphologic left ventricle connects to the aortic valve. Four possibilities exist: concordant (i.e., normal), discordant (i.e., right ventricle to the aorta and left ventricle to the pulmonary trunk), double outlet (usually the right ventricle), and single outlet (i.e., aortic or pulmonary atresia or truncus arteriosus).

• 7.
  

  Ventricular function can be assessed by the shortening fraction. Shortening fraction is calculated by which of the following equations?

  
  
  
  
  • A.
    

    End-diastolic dimension minus end-systolic dimension divided by end-diastolic dimension

    
    
  • B.
    

    End-diastolic dimension minus end-systolic dimension divided by end-systolic dimension

    
    
  • C.
    

    End-systolic dimension minus end-diastolic dimension divided by end-systolic dimension

    
    
  • D.
    

    End-systolic dimension minus end-diastolic dimension divided by end-diastolic dimension

  
  

Preferred response: A

Rationale

Echocardiography is a tomographic anatomic tool, but it also provides dynamic information about cardiac function and structure. Observations about the cardiac walls, including their movement, thickness, and degrees of shortening and thickening, can be extremely useful in determining segmental and global cardiac function. In general, the shortening fraction of the left ventricle should be at least 28% (end-diastolic minus end-systolic divided by end-diastolic dimension), and the walls of the left ventricle should move inward symmetrically.

• 8.
  

  In congenital heart disease, the major application of contrast echocardiography in the postoperative patient is which of the following?

  
  
  
  
  • A.
    

    Assessment of ventricular function

    
    
  • B.
    

    Assessment of coronary arterial flow

    
    
  • C.
    

    Detection of residual shunt lesion

    
    
  • D.
    

    Evaluation of mitral regurgitation

  
  

Preferred response: C

Rationale

An ultrasonic contrast agent is a substance that stabilizes microbubbles in solution, which are large enough to reflect ultrasound but small enough that they disappear rapidly and are physiologically safe. The agent may be as simple as an injection of saline solution into the circulation during two-dimensional echocardiographic imaging or as complex as precision-engineered microbubbles of polysaccharide that dissolve in the circulation after injection. Advances in bubble technology allow imaging of myocardial capillary perfusion. Contrast also can be useful in defining the identity of an imaged structure. For example, a structure under the aortic arch may be confusing but can be confirmed to be the innominate vein by echocardiographic contrast injection in a left arm vein. In persons with congenital heart disease, the major application of contrast echocardiography is in the postoperative patient with residual shunts or as a means to exclude congenital heart disease. Systemic venous injection of contrast fills the right side of the heart sequentially, and the site of residual right-to-left shunting can be defined.

• 9.
  

  The Ross procedure involves which of the following?

  
  
  
  
  • A.
    

    Autologous autograft in the pulmonary position and mechanical prosthesis in the aortic position

    
    
  • B.
    

    Autologous autograft in the aortic position and mechanical prosthesis in the pulmonary position

    
    
  • C.
    

    Mechanical valve in the pulmonary position and autograft in the aortic position

    
    
  • D.
    

    Placement of a pulmonary autograft in the aortic position

  
  

Preferred response: D

Rationale

The Ross procedure involves the substitution of the diseased aortic valve with the patient’s own pulmonary valve (autograft). A pulmonary homograft is then used to replace the patient’s pulmonary valve. The coronary arteries are translocated to the new aortic valve. Advantages of this procedure include the lack of need for anticoagulation because of the decreased incidence of thromboembolism, as well as growth of the valve as the child grows. One disadvantage is the treatment of one-valve disease with a two-valve replacement.

Rationale

The Fick method uses a patient’s oxygen consumption and oxygen carrying capacity across a vascular bed to calculate blood. In patients with single ventricle physiology, the systemic and pulmonary saturations are identical. For this reason, only three saturations are required for calculating Qp:Qs via the Fick method. As per equations in Table 30.1 , the equation to calculate Qp:Qs can be simplified to include only saturations as many of the terms cancel out through division. For this question, Qp:Qs is calculated as: (systemic saturation – mixed venous saturation) ÷ (pulmonary venous saturation – pulmonary artery saturation). Since the systemic and pulmonary arterial saturations are equivalent, (88 − 61) ÷ (98 − 88) = 2.7. Note that a saturation of 88% in a patient with hypoplastic left heart syndrome after stage I palliation suggests significantly increased Qp:Qs as is demonstrated here.

• 2.
  

  A 12-year-old male with no prior history of cardiac disease is admitted to the pediatric intensive care unit with concerns for shock. He has a history of febrile illness with malaise several weeks prior. The patient is tachycardic and tachypneic with a pale appearance. The first Korotkoff sound is heard intermittently with respiration at a systolic blood pressure of 85 mm Hg and consistently at 72 mm Hg. On exam, the patient has weak pulses throughout, jugular venous distension, and distant heart sounds. The electrocardiogram demonstrates sinus tachycardia with beat-to-beat variation in the QRS amplitude. An echocardiogram shows a large pericardial effusion with respiratory variation in mitral inflow by pulse wave Doppler of >20%. Given concern for tamponade, the patient is prepared for a pericardiocentesis. For this patient, select the finding that is NOT representative of tamponade physiology:

  
  
  
  
  • A.
    

    Hypotension

    
    
  • B.
    

    Jugular venous distension

    
    
  • C.
    

    Large pericardial effusion

    
    
  • D.
    

    Pulsus paradoxus

    
    
  • E.
    

    All of the above are required for tamponade physiology

  
  

Preferred response: C

Rationale

If the pericardial effusion accumulates slowly, patients can remain hemodynamically stable and potentially asymptomatic even with a large pericardial effusion. Tamponade is a clinical diagnosis that is characterized by Beck’s triad: distant heart sounds, hypotension, and jugular venous distension. Patients with tamponade also have tachycardia, tachypnea, narrow pulse pressures, and pulsus paradoxus. The ECG and echocardiogram changes may be suggestive of a diagnosis, but must be accompanied by the clinical signs and symptoms to meet a diagnosis.

• 3.
  

  A 2-year-old admitted with tachypnea is referred for catheterization after an echocardiogram demonstrated right heart enlargement and partial anomalous pulmonary venous return. The patient’s baseline hemoglobin is 12.5 mg/dL. The patient is sedated and intubated with fraction of inspired oxygen of 21%. Estimated oxygen consumption (Vo ₂ ) is 150 mL/min/m ² and the following saturations are obtained:

  
  
  
  

  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  

  Innominate Vein	High SVC	Right Atrium	Pulmonary Artery	Pulmonary Vein	Descending Aorta
  71%	70%	85%	86%	99%	99%

   
  
  
  
  
  • 
    

    Calculate the pulmonary blood flow for this patient.

    
    
    
    
    • A.
      

      2.5 L/min/m ²

      
      
    • B.
      

      4.1 L/min/m ²

      
      
    • C.
      

      6.8 L/min/m ²

      
      
    • D.
      

      10 L/min/m ²

      
      
    • E.
      

      Unable to calculate with the given information