Benzodiazepines, ketamine, etomidate, propofol, and nitrous oxide are all well studied agents for ED procedural sedation. Most of these agents have the potential to cause a loss of respiratory drive and airway protective reflexes, and their use is typically limited to physicians specifically credentialed to provide deep sedation who are trained in advanced airway management. Although there are numerous sedative agents that may be used for procedural sedation, it is best to become knowledgeable about and comforTable with only a few agents, to use those agents regularly, and to choose the proper agent or combination of agents most appropriate to the goals of the specific clinical scenario. The traditional continuum of sedation is thought of as starting with moderate sedation (previously called "conscious sedation"), progressing to deep sedation, and then general anesthesia. These terms are fairly arbitrary, however, with considerable overlap. Ketamine is sometimes placed in its own category, "dissociative sedation," because although ketamine causes depressed response to verbal or painful stimuli, it is not expected to have effects on respiratory drive or protective airway reflexes.
In general, procedural sedation can be broken down into five distinct steps:
Determine the indications for sedation and obtain informed consent.
Assess the patient to assure that the child is an appropriate candidate for sedation.
Select the appropriate sedative agents.
Monitor the patient throughout the procedure.
Provide postsedation monitoring until recovery.
INDICATIONS FOR SEDATION AND INFORMED CONSENT
Procedural sedation is commonly used for painful procedures and for those requiring motionlessness in the ED (Table 113-7). Conversely, there are many common ED procedures that do not routinely need sedation (Table 113-8). These are only general guidelines, however, and there is room for individual judgment. Once the decision is made to proceed with sedation, consideration then turns to choosing the proper medication or combination of medications. Obtain informed consent from the responsible adult (see chapter 303, Legal Issues in Emergency Medicine), which involves explaining the anticipated effects and potential adverse effects specific to the medications and procedure.
TABLE 113-7Indications for Procedural Sedation in Children ||Download (.pdf) TABLE 113-7 Indications for Procedural Sedation in Children
|Indications for Procedural Sedation in the ED ||Examples |
|Very painful procedures of any length ||Reduction of fracture |
|Moderately painful protracted procedures ||Incision and drainage of subcutaneous abscess |
|Extreme anxiety or developmental barriers when attempts at anxiolysis have failed ||Developmentally delayed 14-year-old with simple arm laceration |
|Need for complete motionlessness ||Repair of complex facial laceration in a toddler |
TABLE 113-8Common Procedures Not Usually Requiring Routine Procedural Sedation ||Download (.pdf) TABLE 113-8 Common Procedures Not Usually Requiring Routine Procedural Sedation
|Procedures That Do Not Generally Warrant Sedation in the ED ||Examples |
|Short, painless diagnostic procedures ||CT scans (other than when IV contrast is given) |
|Ultra-short painful procedures ||Reduction of nursemaid's elbow or subluxed patella |
|Painful procedures for which adequate analgesia can be provided without sedation ||Simple laceration repair, lumbar puncture |
ASSESS THE PATIENT AND SELECT THE AGENT(S)
Perform a thorough history and physical examination to identify the risk of complications during sedation. Consider contraindications to specific agents at this time. For example, a significant upper respiratory infection or a history of psychosis may make ketamine a poor choice for sedation.
Presedation assessment usually incorporates the American Society of Anesthesiologists classification: (1) normal healthy patient; (2) mild systemic disease; (3) severe systemic disease; (4) severe systemic disease that is a threat to life; (5) moribund patient; (6) brain-dead patient undergoing organ harvest. Children who are in American Society of Anesthesiologists category 3 or higher may not be candidates for elective procedural sedation in the ED, and sedation or general anesthesia in the operating room may be safer. Examples might be children with significant congenital heart disease or children who require multiple pharmacologic agents to maintain hemodynamic stability.
Next, perform a focused airway assessment in order to predict a difficult airway before problems arise. The Mallampati grading system (Figure 113-2) is one commonly used means to predict the technical ease of intubation. High Mallampati scores may also predict difficult bag-mask ventilation and airway obstruction if neuromuscular paralytics are given. Pediatric patients with congenital conditions may present challenging airway abnormalities, including trisomy 21 patients with relatively large tongues and cervical spine instability and patients with Pierre Robin's syndrome with micrognathia. If the clinical scenario allows, consider sedation or anesthesia in the operating room for these children.
Mallampati grading scale for airways.
Determining nil per os (NPO) status is also traditionally emphasized as an important part of the presedation assessment, but there is no correlation between fasting status and the incidence of aspiration or other untoward outcomes in procedural sedation. This is particularly true for ketamine, which is the most widely used sedative agent in children. The Pediatric Sedation Research Consortium documented only a single aspiration in 30,037 pediatric sedations outside the operating room, and this single case occurred in a patient who had fasted >8 hours.10 There is therefore no evidence to support specific fasting requirements before procedural sedation in the ED. The American College of Emergency Physicians Clinical Policy on sedation of pediatric patients in the ED states: "Procedural Sedation may be safely administered to pediatric patients in the ED who have had recent oral intake" (Level B recommendation), although clinical judgment in each specific case is still advised.11
Postoperative vomiting has no relationship to fasting, but vomiting is relatively common after procedural sedation, typically in the recovery phase, and does not usually result in aspiration or other significant adverse outcomes.10 Depending on the medications used, the risk of vomiting may decrease with pretreatment using ondansetron. For example, the incidence of vomiting decreases if children sedated with ketamine are pretreated with ondansetron. Therefore, consider routine use of ondansetron with ketamine, especially in younger adolescents.12,13
High-flow oxygen use during ED procedural sedation with propofol reduces the incidence of hypoxemia, but the clinical significance of this remains unclear.14
Select Medications for Procedural Sedation
Common medications used in procedural sedation in the ED are listed in Table 113-9.
TABLE 113-9Medications for Procedural Sedation ||Download (.pdf) TABLE 113-9 Medications for Procedural Sedation
|Class ||Drug ||Route ||Dose ||Onset ||Duration ||Advantages ||Disadvantages ||Examples ||Comments |
|Anxiolytic ||Midazolam ||PO, PR, IV, IM, IN || |
PO/PR 0.5 milligram/kg
IV/IM 0.05–0.1 milligram/kg
IN 0.2–0.4 milligram/kg
|PO/PR 20–30 min IV 3–5 min IM 10–20 min IN 5–10 min ||1–4 h ||Flexible route of administration ||No analgesia, paradoxical reaction ||Premedication for IV start, laceration repair using local anesthetic ||Acidic, nasal administration stings, may cause increased secretions; oral/rectal slow onset, less predictable |
|Hypnotic/sedative ||Propofol ||IV ||1–2 milligrams/kg, followed by 0.5 milligram/kg repeat doses as needed ||Seconds ||Minutes ||Rapid onset and short duration, motionlessness, muscle relaxant ||No analgesia, respiratory and cardiovascular depressant ||CT scan, LP with topical analgesic, laceration repair, reduction of dislocation ||Non-analgesic, increased requirement for younger patients, painful injection |
| ||Etomidate ||IV ||0.2–0.3 milligram/kg ||Seconds ||Minutes ||Rapid onset, short duration ||No analgesia, myoclonus, respiratory depressant ||CT scan, short procedures requiring motionlessness ||Avoid in patients with increased tone (e.g., CP) due to myoclonic jerks, painful injection |
| ||Pentobarbital ||IV ||1–2 milligrams/kg, repeated every 3–5 min as needed ||<1 min ||15–45 min ||Well studied, motionlessness, neuroprotective ||No analgesia, respiratory and cardiovascular depressant ||CT scan, no reversal agent ||Variable dosing, long recovery times |
| ||Methohexital ||IV ||0.5–1 milligram/kg ||Seconds ||10–60 min ||Rapid onset ||No analgesia, respiratory and cardiovascular depressant ||CT scan, no reversal agent ||— |
|Dissociative ||Ketamine ||IV, IM || |
IV 1–1.5 milligrams/kg
IM 4–5 milligrams/kg
|IV 1–2 min IM 3–5 min ||IV 15 min IM 30–45 min ||Analgesic, anesthetic, motionlessness, respiratory and cardiovascular stimulant, bronchodilator ||Increased intraocular pressure, intracranial pressure, salivation; emetogenic; laryngospasm ||Painful procedures requiring motionlessness (complex lacerations, fracture reductions, I & D), no reversal agent ||Consider pretreatment with ondansetron; atropine and midazolam co-administration unnecessary |
|Combinations ||Fentanyl + midazolam ||IV ||Fentanyl 1–2 micrograms/kg, midazolam 0.05–0.1 milligram/kg ||1–2 min ||1–3 h ||Analgesic and anxiolytic ||Respiratory depressant ||Fracture reduction, reduction of dislocation, laceration repair ||Reversal with flumazenil and naloxone |
| ||Propofol + ketamine ||IV ||Propofol 1 milligram/kg, ketamine 0.5 milligram/kg ||1 min ||Propofol (minutes); ketamine 15–45 min ||Decreased dosing for both agents, complementary side effects (lessens respiratory and cardiovascular depression, emesis) ||— ||Fracture reduction, I & D, complex laceration ||Consider ondansetron pretreatment |
|Other ||Nitrous oxide ||Inhaled ||Titrate to effect ||Minutes ||Minutes ||Self-dosing ||Not readily available ||Adjunct to anesthetics ||— |
Ketamine is a dissociative anesthetic and is the most commonly used medication for procedural sedation of children in the ED in the United States. It is safe and effective in children of all ages and has anesthetic, analgesic, and amnestic effects. It is relatively short acting, poses little risk of respiratory or cardiovascular depression, and has bronchodilatory effects. However, it is emetogenic, particularly in adolescents, and may increase intraocular pressure as well as salivation. Ondansetron administered before sedation with ketamine may reduce the associated nausea and vomiting, which may be particularly true for adolescents and adults.12 A clinical practice guideline for the ED use of ketamine for procedural sedation has been published and updated in 2011.15 Specific changes in the 2011 update include the following: (1) expansion of the guideline to include adults; (2) reduction in minimum recommended age to 3 months; (3) removal of minor oropharyngeal procedures and head trauma as contraindications to ketamine sedation; (4) emphasis on IV over IM route when feasible; (5) removal of recommendation for prophylactic anticholinergic medications or benzodiazepines in children; (6) addition of prophylactic ondansetron to prevent vomiting.
Ketamine does not have a typical dose-response continuum with progressive titration. At doses lower than a threshold, analgesia and sedation occur. Once a critical dosing threshold is exceeded (about 1.0 to 1.5 milligrams/kg IV or 3 to 4 milligrams/kg IM), the characteristic dissociative state abruptly appears.16 This dissociation has no observable levels of depth. The only value of additional ketamine is to prolong the dissociative state for extended procedures.
Sub-dissociative doses (e.g., <1 milligram/kg IV) do have analgesic and amnestic effects despite the lack of a dissociative state. Greater than 90% of children are adequately sedated by a ketamine dose of 1.5 milligrams/kg IV, which is currently the recommended starting dose (1 milligram/kg for adults). Ketamine may also be administered IM at a dose of 4 to 5 milligrams/kg, but IM administration may cause more vomiting and has a prolonged recovery time compared with the IV route. IM ketamine, however, may be advantageous in children in whom IV access is difficult or traumatic (e.g., developmental delay).
Midazolam has often been given along with ketamine to minimize emergence reactions, but research does not support the utility of this practice.17 The use of anticholinergics such as atropine or glycopyrrolate to reduce salivation as adjuncts to ketamine sedation is also unnecessary and no longer recommended in the current clinical practice guideline.18
Opiates are commonly given to children before procedural sedation with ketamine. For example, a painful fracture may be treated with morphine or fentanyl before imaging, with subsequent administration of ketamine for sedation during reduction and splinting. There is no increased incidence of adverse events with the addition of opiates to ketamine.
Propofol is attractive for use in children because of its ultra-short duration of action (shorter than ketamine) and, to a lesser extent, its mildly antiemetic properties. However, propofol provides no analgesia when used alone, so parenteral, local, or regional analgesics/anesthetics must be co-administered with propofol. Because of its short duration of action and recovery time, overall ED length of stay is decreased when propofol is used compared with ketamine. Propofol may cause hypotension and may cause respiratory depression or apnea. These effects are short-lived and not usually clinically significant.19 Hypotension from propofol results from a combination of vasodilation and direct cardiac effects and may be exacerbated in hypovolemic patients; administration of crystalloids before sedation with propofol may be prudent in these patients, though the evidence of benefit is mixed.20,21 Do not administer propofol to children with mitochondrial disorders.22
Propofol is ideal for short procedures requiring complete stillness such as neuroimaging and can be given as a single IV bolus (2 milligrams/kg for infants, 1 milligram/kg for older children). It is particularly useful for ultra-short procedures requiring muscle relaxation such as reduction of dislocations. Propofol can be administered as repeated IV boluses in combination with local, regional, or systemic analgesics for longer procedures (e.g., facial laceration repair) or as a bolus followed by continuous infusion at 100 to 200 micrograms/kg/minute. IV administration may cause local burning at the injection site, which can be mitigated with 0.5 milligrams/kg lidocaine either prior to or mixed with propofol.19
The combination of ketamine and propofol is safe and effective, and the use of both agents together had advantages over either agent used alone.23,24 The two medications have complementary side effect profiles. For example, propofol can cause hypotension and respiratory depression and is an antiemetic, whereas ketamine may cause hypertension and vomiting and has little effect on respiratory drive. When used in combination, lower doses of each agent are used. This results in shorter overall sedation times compared with ketamine alone. In addition, the two medications are pharmacologically compatible and can be given combined in a single syringe (sometimes referred to as "ketofol"). The most common practice is to give a bolus dose of combined ketamine and propofol, followed by repeated doses of propofol as needed to maintain the desired level of sedation (ketamine is longer acting, and does not require titration).
Before the widespread use of ketamine and propofol, midazolam plus opiates—most often short-acting fentanyl—was the combination of choice for pediatric sedation. This combination provides somewhat less predicTable sedation and analgesia, requires careful titration (as opposed to ketamine), and carries the same risks of hypotension and respiratory depression seen with propofol. Although some practitioners still use this combination, ketamine and propofol, with or without adjunct medications, are superior in their effectiveness and safety profile.25
Barbiturates are useful medications when motionlessness is required, such as for imaging, although propofol is largely replacing their use for this indication. Ketamine is not as useful for imaging due to the fact that it does not reliably induce stillness. Both pentobarbital and methohexital have been used for many years for sedation during radiologic procedures and are particularly useful for imaging in the setting of potential intracranial hypertension.26,27 The main drawbacks to these agents include hypotension, respiratory depression, and long recovery times (although methohexital is shorter acting than pentobarbital).
Etomidate is thought to work at the γ-aminobutyric acid receptor to produce hypnosis without analgesia. Most emergency physicians are familiar with etomidate for its use as a sedative during rapid-sequence intubation. When administered for intubation, etomidate provides brief deep sedation with minimal cardiovascular effects, minimal respiratory depression, and maintained or increased cerebral perfusion. Etomidate may be useful for brief, painless procedures requiring stillness, such as neuroimaging. However, etomidate is similar to propofol in that the protective airway reflexes may be briefly reduced or lost, and providers should be prepared to manage the airway when using etomidate for procedural sedation.
Inhaled nitrous oxide is a mild dissociative anesthetic gas that produces anxiolysis, sedation, and analgesia. It is useful for minor procedures such as IV placement and Mediport access. It is commonly administered in up to a 70%/30% mixture with oxygen, has maximal effect within a minute, and wears off quickly upon discontinuation. It does not typically affect hemodynamics, respiratory drive, or protective airway reflexes. It has an excellent and well-documented safety record when used for pediatric procedural sedation in the ED.28 Nitrous oxide does not reliably produce effective sedation for painful procedures such as fracture reduction, however, which limits its utility as a single agent in the ED. As a result, it must often be combined with other agents such as opioids for efficacy. A good combination, which does not require IV access, is intranasal fentanyl with inhaled nitrous oxide. For laceration repair, nitrous oxide can be combined with topical LET® and/or injected local anesthetics.
A disadvantage of nitrous oxide is that it requires patient cooperation, limiting usefulness in young children. In older patients it can be administered using a self-administered demand valve, which limits the degree of sedation, but in young children it must be given by a continuous flow device. In either case, a gas scavenging system is necessary to prevent inhalation by healthcare personnel. The most common adverse reactions are dizziness and vomiting. Hypoxemia is rare, likely because nitrous oxide is administered in combination with oxygen.
Monitoring During Sedation
Some hospital policies require that two physicians must be present throughout the sedation and recovery, but most do not. In an ideal setting, one physician would be responsible for sedation and airway management, and the second would perform the procedure. An experienced pediatric respiratory therapist can sometimes fulfill the role of the second physician.
In instances in which the child may require side or prone positioning (e.g., incision and drainage of buttocks abscess), or when the procedures involve the mouth or airway (dental procedures, intraoral lacerations), establish a plan among all providers for abandoning the procedure and repositioning the patient to open the airway in case of a complication. Suction should be available in the rare event of vomiting during sedation, and providers should be prepared to turn the patient's head in order to avoid aspiration should this occur.
Monitor the child for the entire duration of sedation. Monitored parameters include heart rate, respiratory rate, blood pressure, oxygen saturation, capnography, and electrocardiogram recordings.
Capnography is a noninvasive means to assess baseline end-tidal carbon dioxide at the initiation of sedation and to continuously assess for real-time changes during sedation such as hypoventilation, apnea, or upper airway obstruction. In spontaneously breathing patients, capnography is done with a nasal cannula device, which continuously measures exhaled carbon dioxide, while simultaneously delivering low-flow oxygen (if desired). Capnography can alert the clinician to respiratory depression before it is clinically apparent.29 It is particularly helpful in situations in which clinical observation is difficult, such as in the radiology suite or when patient positioning makes direct assessment of respiratory effort challenging.
The use of supplemental oxygen during sedation, in the absence of oxygen desaturation, is currently considered optional. The administration of supplemental oxygen during sedation may delay or mask the recognition of hypoventilation. If oxygen is administered, it should be in combination with continuous capnography.
Postsedation Monitoring and Recovery
After the procedure, monitor patients until recovery is complete and the child has resumed presedation baseline mental status. Immediately after the procedure, with the cessation of painful stimuli, oversedation and respiratory depression can develop. If using ketamine, even with the addition of ondansetron, nausea and vomiting may occur and should be anticipated. Discharge criteria include the following: normal serial vital signs, including blood pressure and pulse oximetry; return to presedation mental status (if sleeping, the ED staff should be able to easily awaken the patient to presedation mental status); and ability to sit unaided (except when not a baseline skill developmentally). Because nausea and vomiting are common but relatively benign side effects of many sedative agents, a PO trial is not routinely indicated before discharge, although caregivers should be warned that vomiting might occur. Parents should review and understand written postsedation discharge instructions, which warn them to closely observe their child for abnormal somnolence and to restrict activities that require coordination until all medication effects have worn off.