Key Points
- 1.
Cardiac surgical patients are at significant risk from preventable adverse events. These events occur through human error, by either faulty decision making (diagnosis, decision for treatment) or faulty actions (failure to implement the plan correctly).
- 2.
Human error is ubiquitous and cannot be prevented or eliminated by trying harder or by eliminating the one who errs. Reduction in human error requires system changes that prevent errors from occurring (forcing functions) or prevent errors from reaching the patient.
- 3.
Sleep deprivation and fatigue can render a person more likely to make an error. Although residents’ hours are limited, those of other physicians in the United States are not, unlike in other countries.
- 4.
Nontechnical skills such as leadership, communication, cooperation, and situational awareness are critical to patient safety, but they are rarely taught. Distractions, disruptions, noise, and alarms contribute to technical errors and increase mortality rates in cardiac surgery.
- 5.
Communication is the leading root cause of sentinel events, whether through missing information or through misunderstanding. Use of structured communication protocols reduces errors. Handoffs performed without a protocol involve significant numbers of omitted items.
- 6.
Team training reduces surgical mortality rates, but it must be done with careful preparation and with regular retraining.
- 7.
Surgical briefings that use a checklist significantly reduce surgical mortality rates (“World Health Organization Safe Surgery Saves Lives”). Debriefings allow teams to identify hazards and formulate improvements.
- 8.
Simulation is an effective means to teach both technical and nontechnical skills and to allow teams to train for rare but dangerous events.
- 9.
Cognitive aids should be available in every operating room to provide direction during rare crisis events (eg, malignant hyperthermia, pulseless electrical activity).
- 10.
Medication errors occur approximately in 1 in every 150 to 200 anesthetic cases. The Anesthesia Patient Safety Foundation published a set of recommendations to reduce medication errors, including standardization, use of technology such as bar codes and smart infusion pumps, having pharmacy involvement in every step of the medication process, and building a culture of safety.
- 11.
Awareness during anesthesia occurs approximately 1 to 2 times per 1000 anesthetic cases, and it occurs more often in cardiac surgical procedures. Use of a processed electroencephalogram or achieving an end-tidal concentration of 0.7 minimum alveolar concentration is effective in reducing the incidence of awareness.
- 12.
The culture of an organization or a unit contributes significantly to patient safety or danger. Strict hierarchical cultures typically harbor a culture of blame and shame, which inhibits identification and correction of hazards. A “Just Culture” acknowledges that human error occurs and seeks to redesign the system to prevent future errors, but also holds individual persons accountable for willful violations.
This chapter focuses on the long-term complications and management of patients after cardiac surgery in the intensive care unit (ICU) and includes a discussion of specific infections observed in patients after surgery, the management of acute renal failure, and the role of nutritional support in the critically ill. The chapter also covers complications after newer surgical procedures such as transcatheter aortic valve replacement (TAVR), other minimally, invasive hybrid procedures, and long-term complications of ventricular assist devices (VADs) and extracorporeal membrane oxygenation (ECMO). Finally, this chapter concludes with an overview of the numerous ethical dilemmas that this technology has created for patients, families, and clinicians.
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Infections After Cardiac Surgery
Device-Related Infections
Cardiac-Implanted Electronic Devices
As the number of cardiac-implanted electronic devices (CIEDs; eg, pacemakers, cardioverter-defibrillators, cardiac resynchronization therapy) is gradually increasing, their complications, such as infections, are also increasing. CIED-related infections can be difficult to diagnose since echocardiography is less accurate and blood cultures are less sensitive than in endocarditis. Most of the patients exhibit nonspecific symptoms, and fewer than 10% of the patients develop septic shock. The incidence of CIED-related infections varies among studies from between 0.5% and 2.2%, with a twofold to fivefold increase in incidence after a revision. The most common pathogens identified across different studies were staphylococci and other gram-positive bacteria. All-cause mortality associated with CIED-related infection varied between 0% and 35%.
The management of suspected CIED-related infections, including the number and sequence of blood cultures and antibiotic therapy, should be guided by the clinical severity. The treatment recommendations for definite CIED-related infections include early removal of the entire system (ie, all leads and generator) along with appropriate antibiotic therapy.
Ventricular Assist Devices
Left ventricular assist device (LVAD) driveline-related infections occur with an incidence up to 20% and commonly develop more than 30 days after implantation. Infections in patients with LVADs are associated with increased hospitalization, frequent need for reoperation, increased risk of stroke, and delay in heart transplantation. Some authors report a trend toward decreased survival in patients with an LVAD who develop infections.
Patients with LVAD infections tend to have a larger body mass index and frequently have a history of diabetes mellitus. Staphylococcus aureus was the most common organism identified in patients with an LVAD and with sepsis complications. The management of LVAD driveline-related infections potentially requires driveline repositioning or LVAD exchange with antibiotic bead implantation and systemic antibiotic treatment.
Intravascular Devices
Intravascular devices such as arterial, central venous, or pulmonary artery catheters are universally used in patients after cardiac surgery. Patients who have intravascular catheters often acquire bloodstream infections (BSIs), which are associated with prolonged hospitalization and increased risk of mortality. Central line–associated BSI (CLABSI) is defined by the Centers for Disease Control and Prevention (CDC) as bacteremia not related to an infection at another site or two or more positive blood cultures with a common skin contaminant associated with signs and symptoms of infection. CLABSIs are prevalent worldwide, and the rate is almost fourfold higher internationally (7.6 per 1000 central-line days) than the national rate in the United States (2 per 1000 central-line days). The CDC reported a significant reduction of CLABSI incidence in ICUs in the United States in recent years: a 58% reduction from 2001 to 2009. The risk of a BSI for arterial catheters is lower than the risk associated with noncoated, uncuffed, nontunneled short-term central vascular catheters (1.7 vs 2.7 per 1000 catheter days). If arterial catheters are inserted using maximum barrier precautions, then a very low risk of BSIs (0.41 per 1000 catheter days) can be achieved.
The recognized risk factors for the development of CLABSIs were prolonged hospitalization before catheter insertion, femoral and internal jugular catheterization, longer catheterization duration, neutropenia, use of total parenteral nutrition, extensive catheter manipulation, and reduced nurse-to-patient ratio. The majority of CLABSI cases are caused by gram-positive organisms (60%), including coagulase-negative staphylococci (34%), the Enterococcus species (16%), and Staphylococcus aureus (10%); approximately 18% of the reported CLABSI cases were attributable to gram-negative organisms (18%) and to the Candida species (12%).
The prominent reduction of the CLABSI rate with the implementation of various prevention initiatives has prompted the development of many quality improvement initiatives with the goal to achieve a minimum-to-none CLABSI incidence. The CDC published guidelines for the prevention of catheter-related infections (CRIs) in 2011. The summary of the guidelines is presented in Box 32.1 .
Central Venous Catheter Infection Prevention
- •
Use the subclavian site if possible, and avoid using the femoral site
- •
Use ultrasound, if available, to reduce the number of imaging attempts
- •
Use the catheter with the minimum number of lumens necessary
- •
Use strict hand hygiene, skin preparation with an antiseptic, and full barrier precaution for insertion
- •
Maintain aseptic technique through the insertion and care of the catheter
- •
Regularly monitor the catheter insertion site for signs of infection
- •
Use 2% chlorhexidine for daily skin cleansing
- •
Do not routinely replace the catheter to prevent infection
- •
Do not use guidewire to exchange the catheter in case of suspected infection
- •
Remove the catheter when it is no longer necessary
Arterial Catheter Infection Prevention
- •
In adults, radial, brachial, and dorsalis pedis are preferred over axillary and femoral sites
- •
Use a minimum of cap, mask, sterile gloves for arterial catheter insertion, and full barrier precautions for the femoral site
- •
Replace the arterial catheter only when clinically indicated
- •
Remove the arterial catheter when no longer necessary
Sternal Wound Infections
The CDC classifies this surgical site infection as superficial or deep. Based on the CDC definition of a deep sternal wound infection (DSWI), this surgical site infection occurs within 30 to 90 days after a surgical procedure. The incision is dehiscent or deliberately opened, an association exists with fever or localized pain and tenderness, or an abscess has formed. The DSWI is an uncommon but serious complication after cardiac surgery that is associated with unfavorable morbidity and increased mortality.
Old age, diabetes, previous stroke and transient ischemic attacks, congestive heart failure (CHF), and bilateral internal mammary artery grafts for the coronary artery bypass graft (CABG) procedure are risk factors for DSWI after cardiac surgery. Mechanical ventilation duration and ICU and hospital lengths of stay were longer in patients diagnosed with DSWI as compared with patients without DSWI. Staphylococcus aureus and gram-positive bacteria were the most common pathogens. The recommended treatment for DSWI is adequate systemic antibiotic therapy, along with either surgical débridement with antibiotic irrigation and primary closure or sternotomy with flap reconstruction.
Prosthetic Valve Endocarditis
The diagnosis of endocarditis requires a high level of clinical suspicion, considering that the clinical presentation is frequently nonspecific with fever, chills, fatigue, or weight loss. The modified Duke criteria are the gold standard for infective endocarditis (IE) diagnosis: two major, one major and three minor, or five minor clinical criteria are required ( Table 32.1 ). Prosthetic valve IE can occur early (less than 1 year after valve replacement) or late (more than 1 year after surgery). The risk of IE was found to be 1% to 4% early after surgery, and 0.5% to 1% per patient year of prosthetic valve later after surgery. The prosthetic valve and CIED-associated IE incidence has increased in recent years. The reported risk was similar for mitral or aortic valve replacement (AVR), regardless of the type of prosthesis; however, it was higher if more than one valve was replaced. Staphylococcus aureus was reported to be the most common pathogen in prosthetic valve IE (34%), followed by the Streptococcus species (23%), the Enterococcus species (19%), and coagulase-negative Staphylococcus (18%).
| Major Criteria | Minor Criteria |
|---|---|
|
|
Despite the low level of evidence regarding the benefit of antibiotic prophylaxis in the prevention of IE, the current recommendation remains that all patients with prosthetic valves receive antibiotic prophylaxis before dental or surgical procedures. Evidence also suggests that antibiotic treatment decreases the risk of stroke after IE. Based on current guidelines of the American College of Cardiology and the American Heart Association (ACC/AHA), surgery is indicated in prosthetic valve–related IE, resulting in hemodynamic instability, heart failure, or valvular complications such as dysfunction or dehiscence, obstruction or regurgitation, and abscess or fistula formation, but it is not indicated in uncomplicated cases.
Systemic Inflammatory Response Syndrome and Sepsis
Systemic inflammatory response syndrome (SIRS) and sepsis are clinical entities that result from an infection with an inflammatory response. Box 32.2 summarizes the diagnostic criteria for sepsis. The number of sepsis cases reported in the United States exceeds 750,000 per year, of which 50% were treated in ICUs. Fifteen million to 19 million new sepsis cases per year are estimated to develop worldwide each year. Most studies have reported that sepsis mortality remained high over time, and septic shock accounted for the highest mortality, approaching 50%.
Infection Documented or Suspected With Some of the Following Criteria
General Variables
- •
Fever
- •
Hypothermia
- •
Tachycardia
- •
Tachypnea
- •
Altered mental status
- •
Positive fluid balance
- •
Hyperglycemia in the absence of diabetes
Inflammatory Variables
- •
Leukocytosis
- •
Leucopenia
- •
Greater than 10% immature leukocytes
- •
Increased plasma C-reactive protein
- •
Increase plasma procalcitonin
Hemodynamic Variables
- •
Arterial hypotension
Organ Dysfunction Variables
- •
Hypoxemia
- •
Oliguria
- •
Creatinine increase
- •
Coagulation abnormalities
- •
Ileus
- •
Hyperbilirubinemia
Tissue Perfusion Variables
- •
Increased lactic acid
- •
Decreased capillary refill
Some authors report that infections are the most common noncardiac complication after cardiac surgery. Hospital costs, lengths of stay, and readmissions were significantly associated with hospital-acquired infections after cardiac surgery. Another large prospective study revealed that nearly 5% of the patients were diagnosed with major infections (eg, DSWI, mediastinitis, infectious myocarditis or pericarditis, endocarditis, cardiac device infection, pneumonia, empyema, Clostridium difficile colitis, BSI) after cardiac surgery. The risk factors associated with increased infections were chronic lung disease, heart failure, long surgery, emergent surgery, prolonged mechanical ventilation, and postoperative antibiotic administration for longer than 48 hours. Major infections significantly increased the mortality rate after cardiac surgery.
Considering the high mortality and morbidity risk of sepsis, a group of experts representing numerous international organizations launched the Surviving Sepsis Campaign (SSC) and published guidelines in 2003, which were updated in 2012. The SSC guidelines are outlined in Box 32.3 .
Routine screening of patients who are potentially infected and seriously ill is recommended for severe sepsis.
Protocolized resuscitation of patients with hypoperfusion should be initiated during the first 6 hours of recognizing septic shock.
Effective intravenous antimicrobials should be administrated within the first hour of recognizing severe sepsis or septic shock, ideally after culture collection.
Crystalloids should be the initial fluid of choice in the resuscitation of severe sepsis and septic shock. Albumin may be added when substantial amounts of crystalloids are needed.
Norepinephrine should be the first vasopressor of choice. Epinephrine may be added when an additional agent is needed.
Hydrocortisone is not indicated if fluid therapy and vasopressor restores hemodynamic stability. If hemodynamic stability is not achievable, then 200 mg daily hydrocortisone might be beneficial.
Empiric antibiotic combination therapy should not be administered for more than 3 to 5 days. De-escalation to the appropriate single therapy should be performed when available.
The typical antibiotic therapy duration should be 7 to 10 days.
Glucose management in the intensive care unit to maintain glycemia <180 mg/dL is indicated.
Transfusion is indicated only for hemoglobin levels <7 g/dL (with a goal range of 7–9 g/dL) unless severe hypoxemia, myocardial ischemia, coronary artery disease, or acute hemorrhage is present.
Pneumonia
Pneumonia is a difficult diagnosis to make in patients after cardiac surgery because the typical radiographic signs might be confused with postsurgical changes. Pneumonia is an important complication after cardiac surgery. A multicenter study revealed that pneumonia represented 48% of hospital-acquired infections in patients who underwent cardiac surgery. A history of chronic obstructive lung disease is significantly associated with respiratory infection after cardiac surgery.
Approximately 5.5% of patients require prolonged mechanical ventilation after cardiac surgery. Considering the increased mortality and health care costs related to ventilator-assisted pneumonia (VAP), the Institute for Healthcare Improvement (IHI) recommends the use of a five-component ventilator bundle, which has been associated with a lower incidence of VAP: (1) head of the bed elevation; (2) daily sedation interruption and spontaneous breathing trials; (3) peptic ulcer disease prophylaxis; (4) deep vein thrombosis (DVT) prophylaxis; and (5) daily oral care with chlorhexidine.
Urinary Tract Infection
Urinary tract infection (UTI) is one of the most common hospital-acquired infections and accounts for 4.4% of infections after cardiac surgery. Diabetes mellitus and advanced age are associated with increased incidences of UTI in patients after cardiac surgery. Bacteriuria rapidly develops in patients with a urinary catheter, with an average of 3% to 10% per day of catheterization. Bacteriuria is frequently asymptomatic (approximately 90% of cases), and therefore the diagnosis of UTI is primarily clinical. Traditional diagnostic criteria for UTI include the presence of pyuria and great than 10 5 colony-forming units (CFU)/mL urine. UTI treatment is not indicated unless laboratory data are associated with clinical signs and symptoms of infection (eg, temperature >38°C, urgency, frequency, dysuria, suprapubic tenderness). Because 80% of UTIs are attributable to the presence of an indwelling catheter, the removal of unnecessary catheters is recommended.
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Infections After Cardiac Surgery
Device-Related Infections
Cardiac-Implanted Electronic Devices
As the number of cardiac-implanted electronic devices (CIEDs; eg, pacemakers, cardioverter-defibrillators, cardiac resynchronization therapy) is gradually increasing, their complications, such as infections, are also increasing. CIED-related infections can be difficult to diagnose since echocardiography is less accurate and blood cultures are less sensitive than in endocarditis. Most of the patients exhibit nonspecific symptoms, and fewer than 10% of the patients develop septic shock. The incidence of CIED-related infections varies among studies from between 0.5% and 2.2%, with a twofold to fivefold increase in incidence after a revision. The most common pathogens identified across different studies were staphylococci and other gram-positive bacteria. All-cause mortality associated with CIED-related infection varied between 0% and 35%.
The management of suspected CIED-related infections, including the number and sequence of blood cultures and antibiotic therapy, should be guided by the clinical severity. The treatment recommendations for definite CIED-related infections include early removal of the entire system (ie, all leads and generator) along with appropriate antibiotic therapy.
Ventricular Assist Devices
Left ventricular assist device (LVAD) driveline-related infections occur with an incidence up to 20% and commonly develop more than 30 days after implantation. Infections in patients with LVADs are associated with increased hospitalization, frequent need for reoperation, increased risk of stroke, and delay in heart transplantation. Some authors report a trend toward decreased survival in patients with an LVAD who develop infections.
Patients with LVAD infections tend to have a larger body mass index and frequently have a history of diabetes mellitus. Staphylococcus aureus was the most common organism identified in patients with an LVAD and with sepsis complications. The management of LVAD driveline-related infections potentially requires driveline repositioning or LVAD exchange with antibiotic bead implantation and systemic antibiotic treatment.
Intravascular Devices
Intravascular devices such as arterial, central venous, or pulmonary artery catheters are universally used in patients after cardiac surgery. Patients who have intravascular catheters often acquire bloodstream infections (BSIs), which are associated with prolonged hospitalization and increased risk of mortality. Central line–associated BSI (CLABSI) is defined by the Centers for Disease Control and Prevention (CDC) as bacteremia not related to an infection at another site or two or more positive blood cultures with a common skin contaminant associated with signs and symptoms of infection. CLABSIs are prevalent worldwide, and the rate is almost fourfold higher internationally (7.6 per 1000 central-line days) than the national rate in the United States (2 per 1000 central-line days). The CDC reported a significant reduction of CLABSI incidence in ICUs in the United States in recent years: a 58% reduction from 2001 to 2009. The risk of a BSI for arterial catheters is lower than the risk associated with noncoated, uncuffed, nontunneled short-term central vascular catheters (1.7 vs 2.7 per 1000 catheter days). If arterial catheters are inserted using maximum barrier precautions, then a very low risk of BSIs (0.41 per 1000 catheter days) can be achieved.
The recognized risk factors for the development of CLABSIs were prolonged hospitalization before catheter insertion, femoral and internal jugular catheterization, longer catheterization duration, neutropenia, use of total parenteral nutrition, extensive catheter manipulation, and reduced nurse-to-patient ratio. The majority of CLABSI cases are caused by gram-positive organisms (60%), including coagulase-negative staphylococci (34%), the Enterococcus species (16%), and Staphylococcus aureus (10%); approximately 18% of the reported CLABSI cases were attributable to gram-negative organisms (18%) and to the Candida species (12%).
The prominent reduction of the CLABSI rate with the implementation of various prevention initiatives has prompted the development of many quality improvement initiatives with the goal to achieve a minimum-to-none CLABSI incidence. The CDC published guidelines for the prevention of catheter-related infections (CRIs) in 2011. The summary of the guidelines is presented in Box 32.1 .
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