Definition

Sedation may be described as a continuum of states of depressed consciousness. The American Academy of Pediatrics (AAP), the American Society of Anesthesiologists (ASA), and the Joint Commission (TJC) have agreed on standardized definitions to describe sedation depth including minimal sedation, moderate sedation, deep sedation, and general anesthesia. Definitions of sedation states and patient responsiveness are presented in Table 76.1 . The possible “states” or “depths” of sedation have been correlated to the risk of complications based on the extent to which natural airway/vascular tone and protective reflexes have been depressed. Deeper levels of sedation have greater likelihood of depressing airway tone, protective reflexes, respiratory drive, and cardiac function, inherently resulting in greater risks of complications.

Because sedation is a continuum and patient responses to sedating medications are unpredictable, emphasis has been placed on practitioners’ ability to rescue patients from at least one level of sedation deeper than intended. As such, practitioners who administer drugs to achieve minimal sedation must have the skills to rescue a patient who becomes moderately sedated, and practitioners who intend to achieve deep sedation must have the skills to rescue patients from a state of general anesthesia. Because most sedation-related adverse events in children are related to airway compromise or loss of respiratory effort, the most important skills are the appropriate recognition of inadequate ventilation and subsequent advanced airway management. For practical purposes, most children require deep sedation to produce acceptable conditions for prolonged diagnostic or therapeutic procedures. Therefore it is good practice to use the guidelines for deep sedation from the outset of the sedation process.

Sedation adverse events (complications) have been well documented in a number of studies, notably in a report from the Pediatric Sedation Research Consortium (PSRC). In a report of over 30,000 prospectively observed sedation encounters, this group reported the observed complications, which included (but were not limited to) apnea, airway obstruction, laryngospasm, hypoxia, prolonged recovery, and aspiration. There were also a small number of patients with hypotension and bradycardia ( Table 76.2 ). Although the rates for serious adverse events were low, the data confirm that sedation of children involves alterations of consciousness that are associated with partial or complete loss of protective reflexes and more profound changes in central nervous system and cardiopulmonary physiology.

TJC and the Centers for Medicare and Medicaid Services (CMS) have recognized anesthesiologists as experts in managing all levels of sedation/anesthesia, and both organizations have mandated that departments of anesthesia lead the way in developing institutional policies regarding the sedation of all patients, whether adult or pediatric. The intention is to create uniform standards of care regarding the management of patients undergoing sedation/anesthesia within each institution.

Recognition

Appropriate monitoring is critical to recognizing the onset of airway obstruction or changes in cardiovascular stability. The AAP and ASA have set forth appropriate monitoring criteria based on depth of sedation outlined in Table 76.3 . For deeply sedated patients, monitoring electrocardiogram, blood pressure, and pulse oximetry is recommended. Perhaps most important is monitoring of respiration, which can be accomplished through multiple devices/techniques. Most commonly used are impedance plethysmography, direct observation, precordial stethoscopy (or amplified breath sounds), and end-tidal CO ₂ detection/capnography. The use of CO ₂ detection has been widely described and adopted because it can be used in a wide range of sedation environments (including remote locations), and it detects air exchange rather than simply chest wall movement. The use of capnography allows for early detection and correction of impaired ventilation before the onset of hypoxemia.

Monitors alone will not detect complications. The presence of an independent observer who tracks the monitor output and records trends is a critical aspect of sedation complication prevention and management. This observer must have training both in the recognition of potential adverse situations and in appropriate responses to restore patients to a safe baseline. Simulation is a useful tool both to teach basic and advanced sedation skills and to test organizations’ approach to adverse events.

Likewise, sedation often does not end with the completion of a procedure. Patients should be monitored in a fully equipped and staffed recovery area with strict and uniform discharge criteria identical to those used for patients recovering from general anesthesia.

Risk Assessment

Landmark work by Coté and colleagues has identified the fact that most serious complications relating to sedation involve one or more of the following factors:

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  The same person performing the procedure and sedating the child

  
  
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  Residual drug effects combined with inadequate monitoring during recovery

  
  
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  Lack of appreciation for drug-drug interactions and drug dosing errors

  
  
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  Having parents administer a sedating medication at home and then having no one observe the child for signs of airway obstruction

A detailed analysis of sedation accidents conducted by these investigators found that approximately two-thirds of children were younger than 6 years of age, and half received more than one sedating medication. This study also found that adverse outcomes were associated with all routes of drug administration (oral, rectal, nasal, intramuscular, intravenous, inhalation). Twelve patients suffered an adverse event or outcome either on the way to the medical facility (two patients who received sedation at home) or after discharge from medical supervision (10 patients). All patients who suffered an adverse event after discharge had received long-acting sedation medications.

In a series of studies evaluating sedation complications from the PSRC, Cravero and colleagues confirmed the existence of higher-risk pediatric subgroups undergoing sedation. These include young patients, ASA status III or IV, obesity, and those sedated with potent agents such as propofol. High-risk procedures such as bronchoscopy and upper gastrointestinal procedures have also been identified. Serious adverse events were not associated with a particular provider type versus any other. The authors suggest that the relatively low rates of serious adverse outcomes in their data are the result of coordinated sedation services that identify high-risk patients and have excellent monitoring, quality improvement processes, and teamwork.

In response to the data on complications that occur after procedures are completed, Malviya and colleagues examined recovery in toddlers following chloral hydrate sedation for echocardiograms. They found that using discharge criteria based on the patient’s ability to remain awake for 20 consecutive minutes in a soporific environment and on the University of Michigan Sedation Scale resulted in a mean discharge time 75 minutes later than when using standard discharge criteria. This observation suggests that prolonged observation (perhaps in a step-down unit) may improve safety when long-acting medications are used for pediatric sedation.

In summary, the collected literature on sedation clearly supports the concept that sedation risk varies with patient subgroups and procedures, thus requiring a systematic assessment of children requiring sedation, with the goal of significantly reducing anesthetic-related morbidity and mortality.

Implications

It is impossible to simply convince infants, toddlers, and many children to cooperate with diagnostic and therapeutic procedures. Pharmacologic control is required. A long list of medications has been employed over the years in the pursuit of this goal. This includes barbiturates, chloral hydrate, butyrophenones, opioids, phenothiazines, benzodiazepines, and hypnotics such as propofol and dexmedetomidine. For some of these medications or medication combinations, there is a paucity of information regarding pediatric safety and efficacy. This is particularly true as the sedation strategy trends toward deep sedation.

Because there are insufficient numbers of anesthesiologists to provide all of the sedation required for diagnostic and therapeutic procedures in children, many receive procedural sedation from pediatric subspecialists other than anesthesiologists. Propofol sedation provided by providers who are not anesthesiologists has raised concerns regarding the appropriateness of these individuals administering this medication. Anesthesiologists have attempted (in the not-distant past) to restrict the use of propofol and all deep sedation by nonanesthesiologists. Currently, the provision of deep sedation by emergency physicians and other nonanesthesiologists using propofol or other drug regimens is well established. This practice is supported by large-scale studies performed by the PSRC, which have demonstrated that, at least within the confines of established sedation programs, deep sedation can be safely administered outside the specialty of anesthesiology. The ASA has established guidelines for the use of deep sedation and propofol (specifically) by nonanesthesiologists. It is up to our specialty to educate and train these individuals. Indeed TJC and CMS have recognized the importance of anesthesia oversight of sedation in the hospital setting. Regardless of the medications being employed, sedation needs to be provided by physicians and/or nurses who have been appropriately trained to administer it and to recognize and treat its complications.