Chapter 113: Pain Management and Procedural Sedation in Infants and Children

Pain and anxiety are very common experiences for patients of all ages in the ED, and both are frequently undertreated. This is particularly true for children. There are many reasons for this, including the idea that very young children do not experience true pain or will not remember, the perceived difficulty in measuring pain and anxiety in children, fear of masking the signs and symptoms of serious disease processes, concerns that addressing pain takes too much time or effort, and lack of familiarity and comfort with medication dosing in children. These concerns should not stand in the way of providing adequate analgesia, anxiolysis, and sedation for children, however, and addressing these concerns is the primary goal of this chapter.

Caring for children in the ED requires constant attention to pain and anxiety. Common situations include fractures, lacerations, abdominal pain, lumbar puncture, incision and drainage of abscesses, and IV placement. Full procedural sedation may be necessary for invasive procedures in children. This chapter discusses pain management goals (Table 113-1) and pharmacologic and nonpharmacologic measures to minimize pain and anxiety experienced by children in the ED, with an emphasis on both basic concepts and newer developments in this topic of daily relevance to ED care providers.

The first step in the treatment of pain and anxiety in children is to quantify the severity of symptoms. The level of pain or distress may be obvious to the care provider, such as when a child has a visibly displaced fracture. Other scenarios are not as straightforward, however, such as the common complaint of abdominal pain. Preverbal and young children are especially challenging. As a result, specific pain scales have been developed for children at different developmental stages (Table 113-2). Familiarity with and application of these pain scales greatly reduces uncertainty in treating pain and anxiety in children of all ages. In addition, measuring and addressing pain is one of the Centers for Medicare & Medicaid Quality Measures.

Children with cognitive developmental delay may compound the challenges of assessing and treating pain and anxiety by combining the physical size and strength of an older child with the cognitive and behavioral attributes of the young. Furthermore, many of the patients in whom this "cognitive-physical mismatch" exists are medically complex and have already experienced a large number of medical encounters, including painful procedures, so baseline anxiety is high. Relying on parental pain assessment and providing empiric analgesia for procedures that are expected to be painful is the most prudent approach to these children.

INFANTS AND TODDLERS

A variety of pain scales have been developed for use in infants and young children, before they are able to self-report and quantify pain. These scales are based on physiologic parameters such as heart rate and observations of behavioral reactions such as crying, facial expressions, and activity level. In the United States, the FLACC Scale© (Face, Legs, Activity, Cry, Consolability) is most commonly used.

PRESCHOOL CHILDREN

Beginning at about 3 years of age, many children are able to describe and rate pain, and pain scales utilizing self-report become possible and are the preferred means of assessing pain. The most commonly used is the Wong-Baker FACES© pain scale: the child points to one of six face drawings ranging from very happy (0; no pain) to very sad (5; worst pain). Similar scales include the Faces Pain Scale-Revised© (which uses a 0 to 10 scale) and the Oucher Scale© (which incorporates photographs of children instead of simple drawings and offers a variety of ethnic versions). Samples of these scales are readily available online.

OLDER CHILDREN AND ADOLESCENTS

Older children are able to self-report pain and can use numeric pain scales. The Verbal Numeric Scale©, also called the Numeric Rating Scale, rates pain from 0 (no pain) to 10 (worst pain) and is validated in children aged 8 to 17 years.¹ The experience of pain itself is subjective, and self-reported pain assessment is based on prior experiences and varies widely from individual to individual. Nevertheless, assigning a numeric score to pre- and post-treatment pain provides the most objective method available for assessing pain and anxiety.

The approach to analgesia, anxiolysis, and sedation in children consists of five general elements (Figure 113-1). The variables affecting the choices and outcome of pediatric analgesia, anxiolysis, and sedation can also be thought of as four interfacing "domains"—patient, procedure, medications, and setting (Table 113-3).

To choose the best option(s) in any given scenario, assess the child and his/her physical and psychological development, along with the procedure and its level of pain and associated anxiety, and whether the procedure requires complete stillness (such as CT with IV contrast). Synthesize these characteristics to apply the modalities available in the "tool box" (Figure 113-1).

Anxiety potentiates pain, and anxiety itself is unpleasant for children and their families. Common examples of anxiety-provoking procedures are laceration repair and lumbar puncture. Although theoretically both procedures should be nearly painless, particularly with the use of topical anesthetics such as LET^® (lidocaine, epinephrine, and tetracaine, for lacerations) and LMX^® (liposomal lidocaine cream, applied before lumbar puncture), both the waiting period and the procedure itself can be highly anxiety provoking. Anxiety can be addressed in a variety of ways, both pharmacologic and nonpharmacologic.

NONPHARMACOLOGIC ANXIOLYSIS

Parental presence (and sometimes involvement) is a fundamental technique to reduce anxiety that is both cost-free and highly effective. The form of parental presence used may vary by age of the child, but generally, for painful procedures, a well-prepared parent can "coach" the child and reduce anxiety. Allowing the parent on the stretcher with the child is particularly helpful with toddlers and school-aged children.

Distraction for younger children can take the form of picture books, stories read aloud, bubbles, light wands, songs, or music. Guided imagery and hypnosis are both effective but require specific provider training. Education and advance preparation are also useful. Procedures should be explained in a developmentally appropriate context. Child life specialists, if available, are extremely effective in reducing anxiety and acting as patient advocates.

PHARMACOLOGIC ANXIOLYSIS

Benzodiazepines are widely used for their anxiolytic, sedative, amnestic, and hypnotic properties. In the ED, midazolam is almost universally preferred over other agents in this class because of its relatively short duration of action. Midazolam can be given by the intranasal route, which avoids the need for IV access and affords a more rapid onset of action than the oral route. However, benzodiazepines do not have analgesic properties and should be combined with other agents if pain is also an issue. Luckily, fentanyl can also be given by the intranasal route (Table 113-4). Midazolam can cause paradoxical agitation, particularly at lower doses, and can cause respiratory depression and hypotension, particularly in hypovolemic patients. Adjunctive depressant medications can potentiate these effects.

The main advantage of intranasal administration is a more rapid onset of action than the oral route, higher blood levels (by avoiding "first pass effects" of the GI system), and no need for IV placement. High-concentration solutions must be used because the maximum volume that can be delivered to each nostril is limited to approximately 1 mL. Because the medication particles must be within a specific size range (approximately 10 to 50 microns) to be absorbed by the nasal mucosa, commercially available (and inexpensive) "mucosal atomizer devices" are used for intranasal delivery.

Regardless of the route of administration, midazolam is more effective when dosed at the higher end of the range (e.g., 0.4 milligrams/kg for the intranasal route). Oral midazolam (which avoids the nasal irritation of intranasal administration) may be appropriately paired with topical lidocaine-epinephrine-tetracaine suspension for wound repair, as both take 20 to 30 minutes to be effective. Oral midazolam has a longer duration of effect than intranasal or IV preparations, so warn parents to protect the child from falls due to incoordination for several hours after discharge.

When IV access has already been obtained, midazolam may be used IV for anxiolysis, which has the advantage of rapid onset and is easier to titrate than other routes of administration. A lower dose (0.05 to 0.1 milligram/kg IV) is usually sufficient and should be considered, for example, in children and teens requiring lumbar puncture. Higher doses of IV midazolam can cause respiratory depression, and a few children can exhibit a paradoxical reaction to midazolam, with agitation, confusion, or crying. These reactions are self-limited and can occur with PO and intranasal administration. Both paradoxical agitation and respiratory depression may be treated with flumazenil, although this is rarely necessary.

NONPHARMACOLOGIC STRATEGIES

There are a wide variety of nonpharmacologic techniques to reduce pain. Some of them, such as proper immobilization, application of ice, and elevation of fractures, may make a larger difference for the patient than medications. Although techniques such as immobilization are widely known, they are often overlooked, delayed, or omitted. Other techniques include distraction, massage, breathing techniques, acupressure, and emotional support.

PHARMACOLOGIC STRATEGIES

Oral Sucrose for Neonates

Neonates must often undergo unpleasant and painful procedures, and when their pain is not addressed, it can have long-lasting effects on future response to pain. Examples of painful ED procedures include urinary catheterization, venipuncture, heel sticks, IM injections, and lumbar puncture. Oral sucrose is an effective analgesic for brief, painful procedures² and is thought to work by activating endogenous opioids through taste receptors. It is given orally as a concentrated solution by a syringe (e.g., 2 mL of a 24% sucrose solution) or applied to a pacifier. Sucrose solution comes in a variety of commercially available formulations (such as Sweet-Ease^®, a premixed 24% sucrose and water solution). Regardless of the formulation used, oral sucrose reduces physiologic measures of pain (e.g., heart rate), behavioral measures (e.g., time crying), and newborn pain scale scores.

Topical Anesthetics for Intact Skin

Topical anesthetics reduce the pain of minor procedures, such as phlebotomy, Mediport access, and lumbar puncture, and are appropriate for children of all ages. Two commercially available products are EMLA^® and LMX^®. EMLA^® (eutectic mixture of 2.5% prilocaine and 2.5% lidocaine) and LMX^® (4% liposomal lidocaine) are both fat-absorbable creams that anesthetize the skin. The time to maximal effect is up to 60 minutes for EMLA^® and 30 minutes for LMX^®. The use of topical anesthetics may result in a delay in the time to IV access or other procedures, but it is usually appropriate to wait the additional time for the benefit of patient comfort.

Topical Anesthetics for Open Wounds

LET^® (lidocaine 4%, epinephrine 0.1%, and tetracaine 0.5%) is a topical anesthetic mixture for open wounds and is safe and effective for almost all laceration repairs in children. It can be applied to fingers, toes, lips, and other end-organ tissues despite the vasoconstriction effects of the epinephrine.

LET^® is most effective for wounds that are not deeper than the subcutaneous tissues. LET^® should be applied half into the wound and half on a saturated piece of sterile cotton (rather than gauze) at a maximum dose of 0.2 mL/kg. The adequacy of anesthesia from LET^® is highly dependent on proper application technique. LET^® is prepared by hospital pharmacies as a liquid, but is also available commercially as a gel. LET^® should be left in place for at least 20 to 30 minutes for satisfactory wound anesthesia, with longer times (up to 45 minutes or more) generally leading to more complete anesthesia (though highly vascular tissues such as lips require less time). Blanching of the skin from the vasoconstriction effects of epinephrine is a good sign that topical anesthesia has been achieved.

Another option for topical anesthesia prior to procedures such as venipuncture and lumbar puncture is the use of a needle-free injection system. This is a highly effective alternative to EMLA^® or LMX^®, with the major advantage that it is nearly instantaneous.³ Needle-free injection systems deliver lidocaine into the dermis using a self-contained high-pressure delivery system such as a carbon dioxide gas cartridge. The J-tip^® (National Medical Products, Irvine, CA) is currently the most widely used needle-free injection system for local anesthesia.

Local Anesthetic Injection

Slow injection with a small-gauge needle decreases the discomfort of injection. The addition of sodium bicarbonate (typically in a 1:9 ratio) buffers the acidity of lidocaine and further reduces the pain of injection, but must be added immediately before use or precipitation of the solution may result. When possible, regional nerve blocks should be used because they produce a greater area of anesthesia with less medication and can avoid distortion of local tissues in cosmetically important areas such as the lip (see chapter 36, Local and Regional Anesthesia). The onset of action of bupivacaine is slightly longer than that of lidocaine, but it provides much longer lasting anesthesia.

Systemic Analgesia

Oral Agents

Oral acetaminophen and ibuprofen are the mainstays of treatment for mild to moderate pain in children. Unless a specific contraindication to one of these exists, they should be used whenever oral systemic analgesia is required. Codeine has been widely used as an analgesic for many years in children, both alone and in combination with acetaminophen, probably because it is widely available and thought to have a favorable side effect profile. However, the combination of acetaminophen and codeine is no more effective than ibuprofen alone.^4,5 In addition, codeine is poorly efficacious as an analgesic and much less safe than previously believed. As a result, ibuprofen should be considered the first-line oral agent in the treatment of mild to moderate pain in children, particularly for acute musculoskeletal injuries, and is preferred over the use of codeine (with or without acetaminophen). Although laboratory studies in tissue culture demonstrate inhibition of osteoblasts by nonsteroidal anti-inflammatory drugs, no human studies have demonstrated clinically significant delay in fracture healing from their use.^5,6 Oral opioid analgesics such as hydrocodone and oxycodone provide superior analgesia when compared with codeine.⁷ Consider these agents instead of codeine when ibuprofen alone is insufficient. A convenient liquid formulation of hydrocodone plus acetaminophen (7.5 milligrams/500 milligrams per 15 mL) is available both generically and under the brand name Lortab^®, and dosing is simplified by the use of a chart such as that shown in Table 113-5. The liquid opioid/acetaminophen combination should replace the use of codeine/acetaminophen in pediatric practice.

Intranasal Fentanyl

Intranasal fentanyl is an alternative to oral or IV opioids when acute pain management is necessary, the time required for absorption of oral mediations is too long, and IV placement is not otherwise necessary. Intranasal fentanyl at doses of 1.5 to 2 micrograms/kg provides adequate and rapid analgesia comparable to that of IV morphine.⁸ The time to administration of analgesia is reduced when intranasal fentanyl is compared with IV analgesics such as morphine.⁹ Intranasal medications (specifically fentanyl and midazolam) are also useful in the prehospital setting.

IV Nonsteroidal Anti-inflammatory Agents

IV access provides additional options for the acute treatment of pain. IV ketorolac is particularly effective for musculoskeletal pain, the pain of cholelithiasis and ureterolithiasis, and gynecologic pain. It is approved by the U.S. Food and Drug Administration for use in children as young as 24 months. The dose is 1 milligram/kg IM (maximum 30 milligrams) or 0.5 milligram/kg IV (maximum 15 milligrams). Ketorolac is not more effective than ibuprofen or other nonsteroidal anti-inflammatory drugs when given orally and is not approved by the U.S. Food and Drug Administration for use in children.

IV Opiates

Children require more opiates proportionate to their weight than adults. Undertreatment of pediatric pain out of fear of adverse effects of opiates or due to lack of recognition of pain is a common problem in the ED. Morphine, for example, should be administered in doses of 0.1 to 0.2 milligram/kg and can then be repeated at 10- to 15-minute intervals until adequate analgesia is accomplished. For example, an 18-kg 3-year-old might receive 2 to 3 milligrams as an initial dose—nearly the same as the typical 4-milligram "starting dose" for an adult weighing five times as much.

The specific choice of parenteral opiates is determined by the individual characteristics of the drug, the clinical indication, and the patient's prior experience with opiates. Fentanyl, for example, is associated with less histamine release than the nonsynthetic opioids and has a relatively short duration of action, which makes it useful for short, painful procedures. Hydromorphone has a much higher potency than morphine and may be useful for ongoing pain in children (e.g., sickle cell pain crisis) and in children with extensive prior use of opiates.

Table 113-6 lists pediatric parenteral opiates and their individual considerations. If fentanyl is given as a rapid IV bolus or in high doses to younger patients, it can cause the "rigid chest phenomenon," which may require emergency reversal with naloxone or neuromuscular blockade.

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:

1. Determine the indications for sedation and obtain informed consent.

2. Assess the patient to assure that the child is an appropriate candidate for sedation.

3. Select the appropriate sedative agents.

4. Monitor the patient throughout the procedure.

5. 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.

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.

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.

Ketamine

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

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

Propofol and Ketamine

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).

Midazolam and Fentanyl

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

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

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.

Nitrous Oxide

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.