47 Sedation for Diagnostic and Therapeutic Procedures Outside the Operating Room

Richard F. Kaplan, Joseph P. Cravero, Myron Yaster, Charles J. Coté

Risks and Complications Associated with Sedation

Guidelines

Implementation of Sedation Guidelines

Documentation

Specific Sedation Techniques

Local Anesthetics

Anxiolytics and Sedatives

Barbiturates

Opioids

α₂-Adrenoceptor Agonist: Dexmedetomidine

General Anesthetics

THE USE OF SEDATION and analgesia for diagnostic and therapeutic procedures performed by anesthesiologists and nonanesthesiologists outside the operating room (OR) continues to dramatically increase. Millions of such procedures are performed each year throughout the world. Great progress has been made in understanding the need for and the risks associated with sedation and analgesia outside the OR; the mere restraint of a child for a frightening and/or painful procedure is difficult to justify.¹^–⁴ Indeed, the time-honored techniques of immobilization by physical restraint or sedation with archaic medications, such as the “lytic cocktail” (meperidine, promethazine, and chlorpromazine), are unacceptable and were made possible only because children were easily overpowered, not routinely asked if they were in pain, and were unable to withdraw consent. Furthermore, many of these techniques were inefficient and failed to provide the conditions necessary to complete required procedures. Sedation/analgesia for painful procedures performed outside the OR (e.g., bone marrow aspiration, lumbar puncture, repair of minor surgical wounds, insertion of arterial or venous catheters, burn dressing changes, fracture reduction, bronchoscopy, and endoscopy) requires the same attention to detail as for procedures performed in the OR, because sedation levels needed often achieve the state of deep sedation or general anesthesia, particularly in children 6 years of age and younger. Nonpainful procedures often require sedation, immobility, and sometimes breath-holding. Children undergoing diagnostic studies (e.g., computed tomography [CT], magnetic resonance imaging [MRI], positron emission tomography, electroencephalography [EEG], electromyography), or who require high doses of ionizing radiation, also require deep levels of sedation or general anesthesia because they must remain absolutely motionless.⁵ Given these requirements, a team approach is required to provide appropriate care for the child and to provide optimal conditions for the procedure.

Young and developmentally delayed children, are often unable to remain motionless for even short periods of time. Even some older children and adults may be unable to enter the confined space and often frightening environment of a diagnostic imaging scanner. The fear and anxiety associated with procedures are difficult to control and may be exacerbated by parental anxiety, separation from parents, and the pain (or anticipation of pain) from the procedure. Although distraction, guided imagery, and the use of videos and music have clear and documented benefit, they are often not enough to efficiently and successfully complete procedures.⁶^–¹⁰

The pharmacologic armamentarium for sedation for diagnostic and therapeutic procedures has greatly expanded to include drugs classified as sedatives, as well as those classified as general anesthetics. Who uses these drugs and what qualifications are needed by those who provide such sedation is controversial.¹¹ The demand for safe efficient sedation and analgesia outside the OR comes from many sources, including hospital administrators, insurance companies, and medical specialists. Failed sedations for diagnostic or therapeutic procedures are no longer acceptable, as this increases costs and frustrates parents¹²; however, this manpower need has far outstripped the available supply of anesthesiologists. This led to the demand to create sedation services for diagnostic or therapeutic procedures by nonanesthesiologists (i.e., nurse practitioners, pediatricians, emergency medicine physicians, intensivists, and dentists) who often use sedative agents, including general anesthetics. The development of pediatric sedation services has taken many directions. In a 2005 survey of pediatric sedation practice in 116 children’s hospitals in the United States and Canada,¹³ only 50% of the hospitals had a formal pediatric sedation service. Anesthesiologists were the sole sedation providers in only 26% of institutions. A consortium of pediatric hospitals heavily involved in sedation noted that anesthesiologists were involved in 19% of sedation procedures.¹⁴ Even when looking at the use of drugs such as propofol, which is considered a “general anesthetic,” this group noted anesthesiologists involvement only 10% of the time.¹⁵ This chapter will focus on the current definitions of sedation for diagnostic and therapeutic procedures and the goals, risks, and guidelines for creation of safe conditions for children who require sedation for procedures outside the OR.

As anesthesiologists we need to ask—why should we care? We believe that we provide the best, most efficient, and safest conditions for procedures, whether they are painful or not and whether they are in the OR or not. However, there simply aren’t enough anesthesia care providers to meet the ever-increasing demand. Further, after years of training and the ability to provide anesthesia for “big” cases (e.g., liver transplants, craniofacial reconstruction, trauma, etc.), we need to ask ourselves whether we are “overtrained” to care for children who require sedation or anesthesia for procedures outside of the OR, or whether it can be safely done by others with less training. Federal regulatory agencies, hospital administrations, and professional societies have recognized the expertise of anesthesiologists to provide sedation and have required us to lead, teach, and be responsible for oversight and credentialing of all sedation providers. We must “grab this tiger by its tail.”^12,¹⁶

Definition of Levels of Sedation

Several organizations have created guidelines and definitions of sedation for diagnostic and therapeutic procedures in children.¹⁷^–²⁰ The definitions of the American Academy of Pediatrics (AAP), the American Society of Anesthesiologists (ASA), The Joint Commission (previously called the Joint Commission on Accreditation of Healthcare Organizations), and the American Academy of Pediatric Dentistry (AAPD) are the most frequently cited and agreed-upon position statements.^18,^19,²¹^–²³ These organizations defined sedation and analgesia for procedures as a continuum of consciousness to unconsciousness, ranging from minimal sedation (anxiolysis) to moderate sedation (previously, “conscious sedation”) to deep sedation and general anesthesia (Fig. 47-1). Note that a child’s depth of sedation may easily pass from a light level all the way to general anesthesia.²⁴

FIGURE 47-1 The sedation continuum. A patient may readily pass from a light level of sedation to deep sedation or general anesthesia. Health care providers must be prepared to increase vigilance and intensity of monitoring consistent with the depth of sedation.

A clear understanding of the definition of sedation is mandatory to recognize when the child has progressed to a deeper level of sedation than anticipated (i.e., from moderate sedation to deep sedation or from deep sedation to general anesthesia). Recognition of this transition allows escalation of monitoring and care to avoid complications. The AAP, ASA, and The Joint Commission formalized and defined the concepts of minimal sedation, moderate sedation, deep sedation, and general anesthesia. The definitions that follow are taken from The Joint Commission (2010)^25,²⁶ and are in agreement with AAP, AAPD, and ASA definitions^18,^19,²¹:

Minimal sedation (anxiolysis): A drug-induced state during which patients respond normally to verbal commands. Although cognitive function and coordination may be impaired, ventilatory and cardiovascular functions are unaffected (Video 47-1).

Moderate sedation (previously called “conscious sedation” or sedation/analgesia): A drug-induced depression of consciousness during which patients respond purposefully to verbal commands, either alone or accompanied by light tactile stimulation. No interventions are required to maintain a patent airway, and spontaneous ventilation is adequate. Cardiovascular function is usually maintained (Video 47-2).

Deep sedation: A drug-induced depression of consciousness during which patients cannot be easily aroused but respond purposefully after repeated or painful stimuli (note: reflex withdrawal from a painful stimulus is not considered a purposeful response). The ability to independently maintain ventilatory function may be impaired. Patients may require assistance in maintaining a patent airway and spontaneous ventilation may be inadequate. Cardiovascular function is usually maintained (Video 47-3).

General anesthesia: A drug-induced loss of consciousness during which patients are not arousable, even to painful stimuli. The ability to independently maintain ventilatory function is often impaired. Patients often require assistance in maintaining a patent airway, and positive-pressure ventilation may be required because of depressed spontaneous ventilation or drug-induced depression of neuromuscular function. Cardiovascular function may be impaired (Video 47-4).

Painful procedures or nonpainful procedures requiring complete immobility (e.g., diagnostic imaging or radiation therapy) cannot be performed in a child who is moderately (“consciously”) sedated. Most pediatric procedures require deep sedation. The myth that a state of moderate sedation in which children are conscious and simultaneously responsive to voice command while immobile in the face of pain is just that, a myth.²⁷

Assessing the depth of sedation based on the child’s responses to stimulation is illustrated in Figure 47-2. This is a difficult challenge in children and depends on their verbal abilities, age, level of maturity, and underlying condition. A common problem with classifying a child as either moderately or deeply sedated is to misinterpret any movement in response to touch as “purposeful” and therefore a sign of “moderate sedation.” A child who is moderately sedated should respond to touch or firm rubbing by an appropriate response, such as saying “ouch,” pushing your hand away, and pulling up the covers. An inappropriate response, such as nonpurposeful movement, is a sign that the child has progressed to a deeper sedation level, which should lead to an escalation of care because respiratory depression may occur.²⁸^–³¹ Similarly, children who are deeply sedated should respond purposefully to painful stimuli. Reflex withdrawal, a nonpurposeful response or no response to painful stimuli, is a sign that the child has progressed to a level of anesthesia and should be cared for using guidelines and personnel for general anesthesia. Children may quickly move from one level of sedation to another. A study in a large pediatric hospital showed that the goal of either moderate or deep sedation was only attained in 50% to 75% of patients. An awake state was noted in 12% to 28% of children, and a level consistent with general anesthesia was observed in up to 35% of children.³² The need for accurate assessment of the sedated child has brought about several scoring systems.

FIGURE 47-2 Sedated children must be continuously evaluated for depth of sedation and appropriateness of response. As diagrammed here, sedation is a continuum. Note that a purposeful response to voice or light touch is consistent with moderate sedation. A purposeful response to pain is consistent with deep sedation. A nonpurposeful response to pain is consistent with general anesthesia. However, such stimulation often defeats the purpose of the sedation, thus rendering these assessments less helpful unless patient movement is acceptable. None of the current sedation guidelines require such assessments.

*Purposeful: opens eyes, talks back, pushes you out of the way.

^†Nonpurposeful: winces, shrugs shoulders, nonspecific withdrawal to pain.

The Ramsay scale was described by Ramsay and colleagues ³³ in 1974 for the purpose of monitoring sedation with alphaxalone-alphadolone (Table 47-1). It continues to be the most widely used scale for assessing and monitoring sedation in daily practice, as well as in clinical research. It spans the continuum of sedation but does not clearly separate purposeful from nonpurposeful responses. The Ramsey scale has been modified to more clearly coincide with the AAP and Joint Commission guidelines (Table 47-2).³⁴ A score of 2 to 3 is anxiolysis, 4 to 5 is moderate sedation, 6 is deep sedation, and 7 to 8 is general anesthesia.

TABLE 47-1 Ramsay Scale

Level	Characteristics
1	Patient awake, anxious, agitated, or restless
2	Patient awake, cooperative, orientated, and tranquil
3	Patient drowsy, with response to commands
4	Patient asleep, brisk response to glabella tap or loud auditory stimulus
5	Patient asleep, sluggish response to stimulus
6	Patient has no response to firm nail-bed pressure or other noxious stimuli

TABLE 47-2 Modified Ramsay Sedation Scale

Score	Characteristics
1	Awake and alert, minimal or no cognitive impairment
2*	Awake but tranquil, purposeful responses to verbal commands at conversation level
3*	Appears asleep, purposeful responses to verbal commands at conversation level
4^†	Appears asleep, purposeful responses to verbal commands but at louder than usual conversation level or requiring light glabellar tap
5^†	Asleep, sluggish purposeful responses only to loud verbal commands or strong glabellar tap
6^‡	Asleep, sluggish purposeful responses only to painful stimuli
7^§	Asleep, reflex withdrawal to painful stimuli only (no purposeful responses)
8^§	Unresponsive to external stimuli, including pain

^*Minimal sedation.

^†Moderate sedation.

^‡Deep sedation.

^§General anesthesia.

The Observer’s Assessment of Alertness/Sedation (OAA/S) scale ³⁵ is often cited as a scale for sedation. It is scored as follows: 1, no response to shaking; 2, responds to mild prodding; 3, responds to name called loudly; 4, lethargic response to name; and 5, readily responds to name. However, its inability to clearly categorize deep levels of sedation and lack of a clear differentiation between purposeful and nonpurposeful responses limit its usefulness. The University of Michigan Sedation Scale (UMSS)³⁶ is an assessment tool that has been shown to be valid when compared with the OAA/S scale and other scales of sedation (Table 47-3). It readily separates patients into the sedation categories defined by the AAP, ASA, and Joint Commission.

TABLE 47-3 University of Michigan Sedation Scale (UMSS)

Score	Characteristics
0	Awake and alert
1	Minimally sedated: tired/sleepy, appropriate response to verbal conversation and/or sound
2	Moderately sedated: somnolent/sleeping, easily aroused with light tactile stimulation or a simple verbal command
3	Deeply sedated: deep sleep, arousable only with significant physical stimulation
4	Unarousable

These subjective, responsiveness-based assessment tools all have the disadvantage of intermittently stimulating the child during the procedure and thereby undoing the very reason that sedation was given in the first place! Poking or prodding the child to determine their depth of sedation defeats the purpose of sedation in many situations, e.g., infants, developmentally delayed, or procedures requiring immobility. None of the guidelines require this type of assessment. These responsiveness-based definitions are meant to provide a roadmap for safety, with the understanding that a nonresponding child requires an increased level of vigilance and the provider must have the skills to rescue should an adverse respiratory or cardiac event occur.¹² Concerns regarding these types of assessment tools have led to a drive by some to revise the sedation continuum and to use other monitoring to assess level of sedation.³⁷

To address the problem of defining the depth of sedation or anesthesia, a nonstimulating continuous-assessment tool using a processed EEG, as in the bispectral index (BIS) monitor, has been extensively explored. The BIS was derived from empirically estimating processed EEG parameters that best predicted OAA/S scale levels in adult volunteers receiving a wide variety of anesthetics, analgesics, and sedatives.³⁸ BIS values in adults range from 100 to 95, awake; 95 to 70, light to moderate sedation; 70 to 60, deep sedation with low probability of explicit recall; and 60 to 40, general anesthesia.³⁹ Unfortunately, the EEG in children varies markedly with age and drug, precluding accurate measures by the processed EEG.^40,⁴¹ Attempts to correlate BIS values with the depth of sedation in children have had varying success. In healthy children between 1 and 12 years of age who were sedated with chloral hydrate, meperidine and promethazine, midazolam, fentanyl, or pentobarbital, the BIS reading correlated well with the UMSS scores.⁴² In a similar study with children between birth and 18 years of age who received inhalational anesthetics, chloral hydrate, midazolam, and fentanyl,⁴³ the BIS readings validated the sedation scores, although the data identified several important limitations when distinguishing moderate from deep sedation. For example, the researchers concluded that a BIS of 80 is the optimal cutoff for a diagnosis of deep sedation although this value is inconsistent with that found in the adult literature. In children recovering from propofol and remifentanil anesthesia, there was a marked overlap between moderate and deep sedation using both the BIS and the composite A-line autoregressive index (auditory EEG).^44,⁴⁵ From a safety perspective, it is worrisome that the BIS underestimates the depth of sedation with certain medications, such as chloral hydrate.^45,⁴⁶ During pentobarbital sedation, the BIS had “limited ability to distinguish between moderate and deep sedation levels in children.”⁴⁷

Furthermore BIS values are not age specific,^48,⁴⁹ may differ from one side of the head to the other, are diminished in developmentally delayed children,⁵⁰ may increase with larger doses of ketamine because of ketamine-induced central excitation,^51,⁵² and are unaffected even by high-dose dexmedetomidine.⁵³ Therefore the overlap between levels of sedation, the few large well-controlled studies in children, the overall low quality of BIS data in some studies, as well as a lack of information for different age-groups and specific drugs, precludes validation of the BIS for use in sedated children.⁴⁰ In addition, the use of BIS-type monitoring is not feasible for many procedures, such as MRI, CT scans, or those involving the mouth and airway (endoscopy, dental, bronchoscopy), because the monitor is either not compatible, creates artifacts, is easily dislodged, or is in the way of the proceduralist.

The definitions and tools discussed previously attempt to assess sedation and decrease risk by quantitating the response to stimulation or EEG activity. These tools, however, do not directly measure the risk of loss of control of the airway, which is the primary cause of morbidity and mortality during sedation.^54,⁵⁵ The implication is that there is a direct quantifiable correlation between response to touch or painful stimulation and the ability to control the airway. Thus a moderately sedated child who can respond to light touch can protect his or her airway and a deeply sedated child who can respond appropriately only to pain may not be able to protect his or her airway. The important assessment of the child is not the response to stimulation, but the ability to protect the airway. Furthermore, different sedative drugs have different effects on analgesia separate from obtundation of the airway. Propofol is not a profound analgesic but has profound effects on the airway.⁵⁶ Conversely, the sedative dexmedetomidine may provide profound sedation with little depression of respiratory function. Ketamine produces intense analgesia and most children maintain a patent airway and adequate respiratory effort (Table 47-4).⁵⁷

TABLE 47-4 Examples of Sedative Drugs That Have Varying Effects on Response to Pain and Airway Protection

Response to Pain Does Not Predict Airway Maintenance All Drugs Are Different
	Response to Pain	Airway Maintenance
Fentanyl	↓↓	↓
Propofol	±	↓↓
Ketamine	↓↓	±
Dexmedetomidine	↓	+

↓↓↓, Large decrease in response to pain or large effect on airway patency; ↓, some decrease in response to pain or some effect on airway patency; ±, minimal to no effect on response to pain or effect on airway patency; +, no effect on airway patency.

Until recently, a quantifiable metric to assess control of the airway in sedated children was not available.⁵⁸ Studies on the changes of airway dimensions under different anesthetic and sedative agents, the effect of different positions on the upper airway,⁵⁹^–⁶¹ and upper airway collapsibility with different concentrations of sedative drugs provide a more meaningful assessment of airway risk and protection. The profound effect of propofol-induced collapse of the upper airway can be partially mitigated by reducing the dose and including supplemental drugs, such as midazolam and nalbuphine.^62,⁶³

Assessing sedation must also focus on appropriate discharge readiness. Adverse effects, including death, have occurred after premature discharge following sedation for a procedure.⁵⁵ These events have occurred most often when a long-lasting (long half-life) sedative, such as chloral hydrate, has been given (Fig. 47-3). This can result in the child being unable to spontaneously clear his or her airway.⁵⁴ A simple modified “maintenance of wakefulness” score (infants had to stay awake for at least 20 minutes in a quiet environment before discharge) ensured that more than 90% of children had returned to baseline, compared with only 55% of children assessed as “street ready” according to usual hospital discharge criteria.⁴⁴

FIGURE 47-3 β-Elimination half-life of the active metabolite of chloral hydrate, trichloroethanol, in preterm infants, term infants, and toddlers. Note the extremely prolonged half-lives and the large standard deviations in all age groups. Although often thought of as a short-acting sedative, chloral hydrate can have profoundly long sedative effects, with a real possibility of re-sedation after a procedure when the child is left undisturbed. It is for this reason that we recommend a longer period of observation in a step-down area before discharge.

Risks and Complications Associated with Sedation

The foremost goal is to optimize patient safety and thereby decrease the risk and associated complications. The assessment of risk for pediatric sedation must include age, type of procedure, underlying medical conditions and how these might influence the response to sedating medications, intended level of sedation, pharmacology (pharmacokinetics [PK] and pharmacodynamics [PD]) of the medications used, guidelines (i.e., training, equipment, personnel, monitoring), appropriate-for-age fasting, and strict discharge criteria.

A recent area of concern that was not previously recognized in providing safe sedation or anesthesia to small children is whether drugs used for sedation or anesthesia are neurotoxic to children ⁶⁴^–⁷¹; this topic is covered in detail in Chapter 23. More important than the theoretical concern regarding potential neurotoxicity of sedating medications is the more practical risk assessment regarding both inadequate and excessive sedation. Sedation centers in the United States are less likely to offer sedation for painful procedures than similar centers in Europe. Thirty percent of U.S. respondents to a mail survey reported performing bone marrow biopsies in children without significant sedation more than 50% of the time, as compared with 0% of European centers!⁷² When 1140 children (mean age 2.96 ± 3.7 years) were sedated by nonanesthesiologists who followed AAP guidelines for procedures,⁷³ approximately 13% received inadequate sedation.

The psychological consequences of inadequate sedation have not been specifically studied but can be inferred from children’s responses to other stressful situations. Inadequate preoperative sedation is clearly linked to increased anxiety in children and their families. Of children undergoing a stressful anesthesia induction, 54% have postoperative maladaptive behaviors for up to 2 weeks after the experience.⁷⁴ The incidence of these behaviors decreases with the use of appropriate preoperative sedation. Similar sequelae have been reported after repeated invasive procedures in pediatric intensive care units (ICUs).⁷⁵ Although the number of children who developed posttraumatic stress syndrome because of no sedation or less than optimal sedation during diagnostic and therapeutic procedures is unknown, one can assume that it would be similar to that found in the study situations.

There have been many approaches to assess the risk involved in oversedation of children. One approach is to review sedation-related deaths and critical incidents to find common causes. In 2000, a now classic retrospective review was undertaken of 95 cases of sedation-related deaths and critical incidents derived from the U.S. Food and Drug Administration’s (FDA) adverse drug event reporting system, the U.S. Pharmacopeia, and a survey of pediatric specialists.⁵⁴ Although a number of the incidents cited in this study occurred over 20 years ago, the findings remain applicable today. The analysis revealed that, rather than being related to a specific medication, the overwhelming majority of critical events were preventable and caused by operator error or lack of robust rescue systems. Drug interactions were the most common factor, followed by drug overdose, inadequate monitoring, inadequate cardiopulmonary resuscitation skills, inadequate evaluation before sedation, and premature discharge from medical supervision. The report emphasizes that most sedation complications are related to adverse respiratory events (80%); a majority progressed to cardiac arrest, indicating a lack of rescue skills of the practitioners. A disproportionately large number of severe complications and deaths occurred when sedation was performed in offices outside of hospitals, pointing to a lack of trained personnel available for rescue. There was no relationship with class of drug or route of administration, although there was a positive correlation when three or more sedating medications were administered.⁵⁵ Indeed, the combination of a sedative, hypnotic, and an opioid is well recognized as a precursor to significant respiratory depression.

There are many underpowered reports with relatively few patients (n <200) receiving a variety of sedative medications in a variety of settings declaring successful completion of the procedures and no fatalities.⁷⁶^–⁸⁶ Most studies describe adequate conditions and successful completion with no severe outcomes, but with varying frequencies of transient airway obstruction or desaturation. Conclusions often state that the particular technique and sedation providers are safe and effective. An example is a study that prospectively followed 1140 children (mean age 2.96 ± 3.7 years) sedated for procedures by nonanesthesiologists following AAP guidelines and using a quality-assurance tool.⁷³ Neither death nor sedation-induced crises occurred, although they reported a 5.3% incidence of respiratory events, including one in which a child developed apnea. Given that the expected incidence of a sedation-induced crisis should be on the order of one in tens of thousands, it is not surprising that the majority of similar studies are underpowered to report a critical event.⁸⁷

Another approach to assessing safety is to carefully observe relatively small groups of children and track minute-to-minute changes in their level of sedation. This has been accomplished by the creation of the Dartmouth Operative Conditions Scale (DOCS) (Table 47-5).⁸⁸ This scale was derived from observing 110 videos of pediatric sedation outside the OR. The DOCS quantifies the child’s “state” based on observable behavior. Continuously applying this scale allows for careful tracking of level of sedation, effectiveness of sedation, uncontrolled adverse effects, and the timing of induction of sedation and recovery without poking or prodding the child to determine their depth of sedation. These data can help to quantify the quality of sedation and best practices.

TABLE 47-5 The Dartmouth Operative Conditions Scale (DOCS)

Simulations have been used to carefully examine rare adverse effects in pediatric sedation and ability to rescue.^89,⁹⁰ In a simulated scenario of a sedation complication, a standard reproducible event was introduced in which physiologic variables degraded with inappropriate interventions and improved when effective treatment was introduced. The simulation was distributed throughout the hospital and used with different sedation provider teams (e.g., postanesthesia care unit, emergency department [ED], radiology, and sedation unit). The event was videotaped and scored based on deviations from best practice; it quantifies episodes of hypoventilation, apnea, hypoxia, and cardiovascular collapse. Hypoxia and hypotension lasted 90 seconds in the pediatric sedation unit and 360 seconds in the ED and radiology setting.⁹¹ Such studies demonstrate that prospective and retrospective analysis of simulated but rare adverse events can identify areas within the hospital that are in need of improving their clinical skills, and have a positive impact on patient safety.

There has been a recent effort to capture information from the large numbers of pediatric sedation procedures necessary to understand the nature and frequency of adverse reactions to sedation. The Pediatric Sedation Research Consortium (PSRC) comprises a group of over 30 institutions in North America who share prospective data on pediatric sedation.¹⁴ Analysis of the first 30,000 records identified demographics, procedures, sedation techniques, outcomes, and adverse events: (1) there were no deaths and only one cardiac arrest reported; (2) unanticipated admission occurred infrequently, 1 per 1500 sedations; (3) vomiting occurred 1 per 200 sedations, including one aspiration; (4) stridor, laryngospasm, wheezing, and apnea occurred in 1 of 400 procedures; and (5) airway or ventilatory manipulations occurred in 1 time per 200 sedations.⁹¹ Risk factors included age younger than 3 months, ASA physical status 3 or greater, and multiple drug combinations for sedation. The PSRC has also reviewed the incidence of adverse events in 49,386 propofol sedation and/or anesthesia encounters for procedures outside of the OR.¹⁵ Propofol was delivered by multiple providers (anesthesiologists, intensivists, emergency medicine, pediatricians, and radiologists). No deaths were recorded. CPR was required in 2 children (anesthesiologists were not involved in their care) and aspiration occurred in 4 children. Desaturation of less than 90% for more than 30 seconds occurred 154 times per 10,000 sedations/anesthesias; central apnea or obstruction occurred 575 times per 10,000. Stridor, laryngospasm, excessive secretions, and vomiting occurred 50, 96, 341, and 49 times per 10,000, respectively. The most prominent type of complication was related to the airway and occurred 1 out of 65 sedations; 1 in 70 children required airway rescue. Unexpected admissions occurred 7.1 times per 10,000 sedations. When all possible adverse events are considered, anesthesiologists report fewer events than nonanesthesiologists, with an odds ratio of 1.38 (95% confidence interval [CI] of 1.21 to 1.57, P < 0.001).¹⁵ No difference, however, was noted when outcomes were limited only to major pulmonary complications. The authors concluded that propofol sedation and/or anesthesia when given under these strict organized conditions, i.e., following the AAP sedation guideline, with very well-trained providers, can result in effective sedation with a minimal incidence of severe adverse events. The safety of this practice is contingent on the ability to quickly and safely manage less serious events. In a prospective cohort study of 131,751 procedural sedations⁹² in radiology (62%), hematology–oncology (11%), and minor medical or surgical procedures (16%), in which sedation included primarily propofol (60%), midazolam (25%), and others provided by anesthesiologists, emergency physicians, intensivists, pediatricians, and “other” (pediatric residents, radiologists, dentists, surgeons, and nurses), the rate of major complications per 10,000 sedations (and 95% CIs) were: anesthesiologist 7.6 (4.6 to 12.8), emergency physician 7.8 (5.5 to 11.2), intensivist 9.6 (7.3 to 12.6), pediatrician 12.4 (6.9 to 20.4) and “other” 10.2 (5.1 to 18.3). There were no statistical differences between any providers before or after potential confounding variables (age, ASA status, fasting status, propofol use). A significant limitation of the study was the selection bias that was introduced because not all sedation areas within each hospital reported data and the providers were not randomized. The study did not track whether high-risk patients were referred to practitioners outside of their sedation practice (i.e., the anesthesia service). Only major complications and not minor but dangerous complications (i.e., desaturation, hypoventilation, and need for airway support) were monitored. The participants in these hospitals are highly motivated, and application of these data outside of the consortium requires rigorous evaluation of safeguards and training. The ASA thinks that anesthesiologist participation in all deep sedation is the best means to achieve the safest care. The ASA acknowledges that nonanesthesiologists administer or supervise the administration of deep sedation and has created guidelines to help anesthesiologists provide leadership in this area.^93,⁹⁴

Guidelines

The first sedation guidelines were published in 1985 from the Committee on Drugs, Section on Anesthesiology, American Academy of Pediatrics.⁹⁵ These guidelines provided the first framework to improve safety for children requiring sedation for a procedure. The guidelines emphasized systems issues, such as the need for informed consent, appropriate fasting before sedation, frequent measurement and charting of vital signs, the availability of age- and size-appropriate equipment, the use of continuous physiologic monitoring, the need for basic life support skills, as well as proper recovery and discharge procedures. The guidelines stated that an independent observer whose only responsibility was to monitor the child was required for deep sedation. Advanced airway and resuscitation skills were encouraged but not required. In 1992, the guidelines were revised⁹⁶ emphasizing that a child could readily progress from one level of sedation to another and that the practitioner should be prepared to increase vigilance and monitoring as indicated. In 2002, the same Committee on Drugs of the AAP updated and amended the guidelines.⁹⁷ It eliminated the use of the confusing term conscious sedation and replaced it with the term moderate sedation. It also emphasized the application of these guidelines outside the hospital, in recognition of the relatively high complication rate in non–hospital-based settings. The ASA guidelines in use today were updated in 2002 and, in many respects, modeled after the AAP guideline.⁹⁸ These guidelines were systematically developed by a task force of 10 members. The task force reviewed the strength of evidence and made recommendations that include the following:

Patient Evaluation: Clinicians should be familiar with the sedation-related aspects of the patient’s medical history. These include (1) abnormalities of major organ systems, (2) previous adverse effects with sedation and general anesthesia, (3) drug allergies, current medications, and drug interactions, (4) time and nature of oral intake, and (5) history of tobacco, alcohol, or substance abuse. A focused physical examination, including vital signs, auscultation of the heart and lungs, and evaluation of the airway, is recommended.

Preprocedural Preparation: Patients should be informed of and agree to sedation, including its risks, benefits, limitations, and alternatives. Sufficient time should elapse before a procedure to allow gastric emptying in elective patients. Minimum fasting periods of 2 hours (clear liquids), 4 hours (breast milk), and 6 hours (infant formula, nonhuman milk, and light meal), are recommended for healthy patients. If urgent, emergent, or other situations impair gastric emptying, the potential for pulmonary aspiration of gastric contents must be considered in determining the target level of sedation, delay, or intubation.

Monitoring Level of Consciousness: Monitoring of verbal commands should be routine during moderate sedation, with the exception of young children and mentally impaired, uncooperative patients, or when the response would be detrimental. During deep sedation the response to a more profound stimulus should be sought to be sure the patient has not drifted into general anesthesia.

Physiologic Monitoring: All patients undergoing sedation/analgesia should be monitored by pulse oximetry with appropriate alarms. In addition, ventilatory function should be continually monitored by observation or auscultation. Monitoring of end-tidal carbon dioxide (etco₂) should be considered for all patients receiving deep sedation and for patients whose ventilation cannot be directly observed during moderate sedation. Multiple studies have confirmed the usefulness in etco₂ monitoring especially during deep sedation. Although not currently required, adverse events can be anticipated and corrected by using etco₂ monitoring.⁹⁹ It should be noted that ASA standards for basic monitoring have been amended to include etco₂ monitoring for all sedated patients beginning in 2012.^99,¹⁰⁰ When possible, blood pressure (BP) should be determined before sedation/analgesia is initiated. Once sedation/analgesia is established, BP should be measured at regular intervals during the procedure, unless such monitoring interferes with the procedure (e.g., pediatric MRI, in which stimulation from the BP cuff could arouse an appropriately sedated child). Electrocardiographic (ECG) monitoring should be used in all children during deep sedation, and during moderate sedation in those with significant cardiovascular disease or those who are undergoing procedures in which dysrhythmias are anticipated.

Recording of Monitored Parameters: For both moderate and deep sedation, the child’s level of consciousness, ventilatory and oxygenation status, and hemodynamic variables should be assessed and recorded at a frequency that depends on the type and amount of medication administered, the length of the procedure, and the general condition of the patient. At a minimum, this should be (1) before the beginning of the procedure; (2) after administration of sedative/analgesic agents; (3) at regular intervals during the procedure; (4) during initial recovery; and (5) just before discharge. If recording is performed automatically, device alarms should be set to alert the care team to critical changes in patient status. (Children’s National Medical Center [CNMC] hospital policy requires recording of vital signs every 15 minutes and every 5 minutes for moderate and deep sedation, respectively.)

Availability of an Individual Responsible for Patient Monitoring: A designated individual, other than the practitioner performing the procedure should be present to monitor the child throughout procedures performed with sedation/analgesia. During deep sedation, this individual should have no other responsibilities. However, during moderate sedation, this individual may assist with minor, interruptible tasks once the patient’s level of sedation/analgesia and vital signs have stabilized, provided that adequate monitoring for the child’s level of sedation is maintained.

Training of Personnel: Individuals responsible for children who receive sedation/analgesia should understand the pharmacology of the medications that are administered, as well as the role of pharmacologic antagonists for opioids and benzodiazepines. Individuals who monitor children who receive sedation/analgesia should be able to recognize the associated complications. At least one individual capable of establishing a patent airway and positive-pressure ventilation, as well as a means for summoning additional assistance, should be present whenever sedation/analgesia is administered. It is recommended (although not specifically stated) that an individual with advanced life support skills be immediately available (within 5 minutes) for moderate sedation; such an individual must be within the procedure room for deep sedation.

Availability of Emergency Equipment: Pharmacologic antagonists, as well as appropriately sized equipment for establishing a patent airway and providing positive-pressure ventilation with supplemental oxygen, should be present whenever sedation/analgesia is administered. Suction, advanced airway equipment, and resuscitation medications should be immediately available and in good working order. A functional defibrillator should be immediately available whenever deep sedation is administered and when moderate sedation is administered to those with mild or severe cardiovascular disease.

Use of Supplemental Oxygen: Equipment to administer supplemental oxygen should be present when sedation/analgesia is administered. Supplemental oxygen should be considered for moderate sedation and should be administered during deep sedation unless specifically contraindicated for a particular child or procedure. If hypoxemia is anticipated or develops during sedation/analgesia, supplemental oxygen should be administered.

Combinations of Sedative/Analgesic Agents: Combinations of sedative and analgesic agents may be administered as indicated for the procedure being performed and the condition of the child. Ideally, each component should be administered individually to achieve the desired effect (e.g., additional analgesic medication to relieve pain; additional sedative medication to decrease awareness or anxiety). The propensity for combinations of sedative and analgesic agents to cause respiratory depression and airway obstruction emphasizes the need to appropriately reduce the dose of each component, as well as the need to continually monitor respiratory function (Fig. 47-4).

Titration of Intravenous Sedative/Analgesic Medications: Intravenous (IV) sedative/analgesic drugs should be given in small, incremental doses that are titrated to the desired end points of analgesia and sedation. Sufficient time must elapse between doses to allow the effect of each dose to be assessed before subsequent drug administration. When drugs are administered by non-IV routes (e.g., oral, rectal, intramuscular [IM], transmucosal), allowance should be made for the time required for drug absorption before supplementation is considered. Because absorption may be unpredictable, administration of repeat doses of oral medications to supplement sedation/analgesia is not recommended.

General Anesthetic Induction Agents Used for Sedation/Analgesia (Propofol, Methohexital, Ketamine): Even if moderate sedation is intended, children who are sedated with either propofol or methohexital by any route should receive care consistent with that required for deep sedation. Accordingly, practitioners who administer these drugs should be qualified to rescue the children from any level of sedation, including general anesthesia. Children who are sedated with ketamine should be cared for in a manner consistent with the level of sedation that is achieved.

Recovery Care: After sedation for diagnostic and therapeutic procedures, the children should be observed in an appropriately staffed and equipped area until they are near their baseline level of consciousness and are no longer at increased risk for cardiorespiratory depression. Oxygenation should be monitored periodically until they are no longer at risk for hypoxemia. Ventilation and circulation should be monitored at regular intervals until the children are suitable for discharge. Discharge criteria should be designed to minimize the risk of central nervous system (CNS) or cardiorespiratory depression after discharge from observation by trained personnel.

Consultation and Availability of an Anesthesiologist: Whenever possible, appropriate medical specialists should be consulted before sedating children with significant underlying conditions. The choice of specialists depends on the nature of the underlying condition and the urgency of the situation. For severely compromised or medically unstable children (e.g., anticipated difficult airway, severe obstructive pulmonary disease, or congestive heart failure), or if it is likely that sedation to the point of unresponsiveness will be necessary to obtain adequate conditions, practitioners who are not trained in the administration of general anesthesia should consult an anesthesiologist (Table 47-6).

FIGURE 47-4 Relationship between ventilation and carbon dioxide is represented by a family of curves. Each curve has two parameters, an x-intercept and a slope. Sedatives and opioids increase the intercept and decrease the slope. The combination of sedatives and opioids produce the most profound effect.

(From Yaster M, Nichols DG, Deshpande JK, Wetzel RC. Midazolam-fentanyl intravenous sedation in children: case report of respiratory arrest. Pediatrics 1990;86:463-7.)

TABLE 47-6 Guidelines for the Consultation of an Anesthesiologist

1. Medical Problems

• ASA Physical Status III or IV

• Pulmonary: airway obstruction (tonsils/adenoids)—loud snoring, obstructive sleep apnea. Poorly controlled asthma, congenital or acquired anomalies of the airway or face (Trisomy 21, Pierre Robin syndrome, Treacher Collins syndrome, Crouzon disease, tracheomalacia)

• Morbid obesity (≥2 times ideal body weight, BMI > 30 kg/m²)

• Cardiovascular: cyanosis, repaired or unrepaired congenital heart disease with significant symptoms of cyanosis or congestive heart failure

• Prematurity: less than 60 weeks postconceptional age at time of sedation

• Residual pulmonary, cardiovascular, gastrointestinal, neurologic problems

• Neurologic: developmental disabilities, poorly controlled seizures, central apnea

• Gastrointestinal: uncontrolled gastroesophageal reflux

• Severe liver of renal disease

2. Procedures requiring deep sedation in patients with a full stomach

• Emergency Procedures

3. Management problems

• Severe developmental delay

• Patients who are difficult to control

• Severe attention deficit disorder (paradoxically, the child may develop increased agitation during or after the procedure)

4. History of failed sedation

• Oversedation (loss of airway reflexes)

• Inability to adequately sedate

• Hyperactive (paradoxical) response to sedatives

ASA, American Society of Anesthesiologists; BMI, body mass index.

The above ASA guideline pertains to all age-groups. The AAP’s most recent guideline update was published in 2006.¹⁸ In general, their updated guideline reinforces the ASA guideline. The AAP updated revision retains the same definitions of the continuum of sedation that are identical to the ASA and Joint Commission definitions. The AAP guidelines emphasize a systematic approach to sedation that includes:

No administration of sedative medications without the safety net of medical supervision (i.e., no sedative medications given at home)

Careful presedation evaluation to include review of pertinent medical and surgical conditions

Careful history for ingestion of nutraceuticals and other medications that may alter drug metabolism and prolong sedation

A “time out” should be performed before sedation

Appropriate fasting guidelines for elective and urgent procedures. There should be a balance between the depth of sedation and the risk for those who are unable to fast because of the urgent nature of the procedure

Focused airway examination with particular attention to anatomic airway abnormalities and enlarged tonsils

Understanding of the pharmacologic and PD effects of sedation medications and drug interactions

Appropriate training and skills in airway management to allow for rescue. Deep sedation requires training in pediatric advanced life support

Immediate availability of size- and age-appropriate airway, monitoring, and resuscitation equipment

Appropriate medications and reversal agents

Sufficient numbers of sedation providers to carry out the procedure and monitor the child

Appropriate physiologic monitoring during and after the procedure; use of capnography is encouraged

Appropriate recovery personnel, monitoring, and discharge criteria with return to baseline condition before discharge

Prolonged observation in a step-down unit of children who have been sedated with drugs known to have a long half-life (e.g., chloral hydrate, “lytic cocktail” [see later discussion])

Continuous quality improvement to track common markers of potential safety issues, such as desaturation events, airway obstructions, laryngospasm, unplanned hospital admission, unsatisfactory sedation, and medication errors

Use of simulators to practice how to manage rare adverse events

Assume all children younger than 6 years of age to be deeply sedated from the beginning of the sedation process

Other organizations, including the American College of Emergency Physicians (ACEP), published their own sedation guidelines.¹⁰¹^–¹⁰⁵ The latter guidelines are distinguishable from the AAP and ASA guidelines in several respects, including the definition of the continuum of sedation. The ACEP guideline does not use the terms “moderate” or “deep” sedation but rather the term “procedural sedation.” It is defined “as a technique of administering sedatives, analgesics, dissociative agents, alone or in combination to induce a state that allows the child to tolerate unpleasant procedures while maintaining cardiopulmonary function.” It is intended to result in a depressed level of consciousness but one that allows the child to “independently and continuously” control their own airway. Unfortunately, the lack of uniform agreement on definitions and overlap of “procedural sedation” into “deep sedation” and “anesthesia” has led to considerable confusion and debate among practitioners. In 2006 the ASA asserted that “privileges to administer deep sedation should be granted only to practitioners who are qualified to administer general anesthesia.”^93,⁹⁴ Intensivists and emergency room physicians took umbrage with the ASA “usurping” control over their sedation practice.¹¹ They pointed out that their specialties have been using drugs, such as propofol and ketamine, for procedural sedation with minimal complications at levels that are considered deep sedation or anesthesia for many years,^106,¹⁰⁷ and that they resent an outside organization imposing guidelines on their practices. In 2010 the ASA acknowledged that Medicare regulations permit some non–anesthesia practitioners to administer deep sedation and created guidelines to help hospital directors of anesthesia services grant privileges to such individuals.⁹³ The guidelines include: formal training in administration of deep sedation during residency training (within 2 years) or an Accreditation Council for Graduate Medical Education accredited training program; experience and competency in managing sedated patients; clinical experience with more than 35 patients; knowledge of ASA guidelines; advanced cardiac life support training; and quality assurance tracking. Separate privileging is required for the care of children. The exact nature of these requirements are not specified, but are over and above baseline competencies and dependent on the hospital’s director of anesthesia services.