Carmen D. Sulton, MD, FAAP, FACEP, Assistant Professor of Pediatrics and Emergency Medicine, Emory University School of Medicine, Atlanta
Lauren S. Middlebrooks, MD, FAAP, Assistant Professor of Pediatrics and Emergency Medicine, Emory University School of Medicine, Atlanta
Taryn Taylor, MD, MEd, FAAP, FACEP, Assistant Professor of Pediatrics and Emergency Medicine, Emory University School of Medicine, Atlanta
Steven Winograd, MD, FACEP, Attending Physician, Mt. Sinai Queens Hospital Center, Assistant Clinical Professor of Emergency Medicine, Mt. Sinai Medical School, Jamaica Queens, NY
• Currently, pediatric airway emergencies that require a secure and advanced airway range from 0.6 to 3.3 per 1,000 cases. The median age often varies by institution; however, the highest risk patients commonly are younger than 12 months old.
• Rapid sequence intubation (RSI) is an airway management technique that induces immediate unresponsiveness (induction agent) and muscular relaxation (neuromuscular blocking agent) and is the fastest and most effective means of controlling the emergency airway.
• Apneic oxygenation is an easily applied intervention associated with decreases in hypoxemia during pediatric endotrachial intubation.
The skill to assess and manage the pediatric airway is essential. Correlating anatomic considerations with the need for escalating airway management is critical to optimize each child's outcome.
— Ann Dietrich, MD, Editor
Epidemiology: Pediatric Airway Emergencies
Respiratory emergencies are some of the most common emergency department (ED) chief complaints. Currently, pediatric airway emergencies that require a secure and advanced airway range from 0.6 to 3.3 per 1,000 cases. The median age often varies by institution; however, the highest risk patients are commonly younger than 12 months old.1,2 Pediatric airway emergencies traditionally are managed with conventional airway equipment and techniques. Respiratory failure due to asthma, bronchiolitis, trauma, and foreign bodies often necessitates advanced airway techniques. While intubations in general are rare, they require skill, planning, and teamwork.3
Pediatric Upper Airway: Basic Anatomy
The pediatric airway can be divided into three basic components/segments: the supraglottic segment, the glottic segment, and the intrathoracic segment. The supraglottic component is the most collapsible component of the upper airway. The glottis or laryngeal component of the upper airway consists of the vocal cords and trachea. The intrathoracic segment consists of the thoracic trachea and bronchi.
There are several factors that fundamentally distinguish the pediatric airway from the adult airway. First, the pediatric airway is shorter in length and smaller in diameter.4 This often narrows the field of vision when assessing the airway. Children have large occiputs, so placing a cloth roll under their shoulders often will aid in maintaining a neutral airway, also called the “sniffing position.” Other unique anatomic pediatric features include hypertrophied adenoids and vocal cords that are somewhat narrowed. The tongue in children often is noted to be large relative to the size of the oropharynx.5 In addition, in infants and children, the larynx is located more anteriorly, and the epiglottis is narrow, curved, and floppy, and often described as omega-shaped. This can make this structure difficult to mobilize and control with the laryngoscope blade. The trachea is more compressible and thus, cricoid pressure often is less helpful when accessing the airway. In children who are younger than 10 years of age, the narrowest portion of the airway is at the level of the cricoid cartilage, below the level of the glottis. This is at approximately the level of C4 in children and at the level of C6-C7 in adults.6 This comparison is diagrammed in Figure 1. Lastly, pediatric patients have developing teeth that are easily injured, avulsed, and/or aspirated. The underlying alveolar ridge contains tooth buds that are susceptible to injury and disruption.7
There are several measures that may serve effectively and efficiently as adjuncts. The most common are the oropharyngeal airway (OPA) and nasopharyngeal airways (NPA). These devices may relieve upper airway obstruction caused by the tongue.
An OPA can be used in an unconscious child with no gag reflex. It is a helpful tool when airway readjustment or jaw thrust has failed and an unobstructed airway is needed. The OPA is made of hard plastic and consists of a bite block as well as a conduit for suction. The use of a tongue blade may aid in successful insertion. However, the practice of inserting the OPA backward and rotating it 180 degrees to fit in the mouth, as often is seen in adults, may cause soft tissue trauma in children. The OPA is measured from the corner of the mouth to the angle of the jaw. It is critical to select the correct size OPA. If it is too large, the OPA can obstruct the airway and cause trauma to the larynx. If it is too small, the OPA can push the tongue back into the airway, also contributing to obstruction.3 OPAs come in a variety of sizes, from 4-10 cm.
Nasopharyngeal (NP) tubes can be used in a similar fashion and are a helpful tool for upper airway obstruction. NP tubes should not be used on victims with suspected head trauma or skull fractures. They can be used in conscious or semiconscious patients and often are made of soft plastic. An NP tube is best measured from the nares to the tragus of the ear. The NP tube may lacerate adenoidal tissue so adenoidal hypertrophy is a relative contraindication for NP tube placement. NP tubes come in a variety of sizes from 12F-30F.3 Examples of oral and nasopharyngeal airways, in various sizes, are shown in Figure 2.
The first step in assessing and managing the pediatric airway involves having the necessary equipment available and appropriately sized. Supplemental oxygen with a bag and mask is crucial prior to the establishment of any advanced airway. A bag and mask should be at the bedside at all times. The pediatric mask should measure from the bridge of the nose to the cleft of the chin, forming a tight seal. A poorly aligned face mask can contribute to ineffective ventilation and oxygenation. Two commonly used ventilation devices are the self-inflating bag and the flow-inflating bag. Self-inflating bags often are used for initial resuscitations and fill with either oxygen or room air. Flow-inflating bags require an oxygen source for operation. Being trained and experienced at bag and mask ventilation is the first step in successful management of the pediatric airway.3
For most children, the size of the endotracheal tube (ETT) can be calculated using standard formulas and calculations. In the past, uncuffed tubes were the standard of care for younger children (younger than 8 years of age) because of concerns about airway trauma and post-extubation stridor. Currently, however, most standard ETTs have low-pressure cuffs with minimal risk for airway trauma, airway edema, or need for post-extubation steroids, so cuffed endotracheal tubes are recommended as the initial tube choice.8 Using a cuffed tube has been shown to decrease the incidence of subsequent tube changes. Specific indications for cuffed tubes include concern for aspiration and the ability to ventilate at lower peak pressures. Calculating ETT sizes is standardized by age. They are measured in millimeters by diameter. The common formula is: (age/4) + 4 for uncuffed tubes and (age/4) + 3.5 for cuffed tubes. Length-based pediatric emergency measurement tapes (i.e., Broselow) are helpful for determining appropriate ETT sizes. Regardless of the measured size, it is crucial to have one size larger and one size smaller at the bedside when securing an airway should one size not have an appropriate seal. Research shows that ETT cuffs should be inflated to no more than 20-25 cm H2O.3 Essential bedside airway equipment is described in Table 1.
The goal of selecting the laryngoscope blade should be for the operator to reach the glottic structures while controlling the tongue effectively. The two components of the laryngoscope are the handle and the blade.7 Although smaller handles often are preferred for smaller blades, this selection ultimately is the provider’s preference. Laryngeal blades can be curved or straight. Curved blades should follow the tongue and end in the epiglottic vallecula. Straight blades allow lifting of the epiglottis to expose the glottic opening.9 (See Figure 3.)
Additionally, having all the required advanced airway equipment at the bedside is necessary. This includes all airway adjuncts as described earlier, oxygen sources, bag and mask, and intubation medications. There are several mnemonics to help organize the necessary airway equipment prior to the intubation procedure. One common mnemonic is “SOAPME,” which stands for:
- Suction: appropriately sized suction catheter and suction apparatus (i.e., Yankauer suction);
- Oxygen: adequate oxygen supply, functioning flow meters, and appropriate oxygen delivery devices;
- Airway: appropriately sized airway equipment. This includes nasopharyngeal airways, oral airways, laryngoscope blades (which have been checked, light working), ETTs, laryngeal mask airways, bag-valve-mask (checked for size);
- Pharmacy: all resuscitation medication drugs needed for an emergency and all reversal medications, as well as sedative medications and sedative antagonists;
- Monitors: pulse oximeter with size-appropriate probes as well as blood pressure cuffs, ECG, stethoscopes, and end-tidal monitoring as needed;
- Extra equipment: any extra equipment as needed.
Identifying Difficult Airways
Assessing a difficult airway can be challenging for children, secondary to a lack of patient cooperation.10 Commonly used in adults, tools such as Mallampati scoring are attractive because they are noninvasive and quick. This scoring system describes visualization of the tonsils and uvula. They have been accepted by specialists, such as anesthesiologists, as a guide for assessing ease of intubation; however, the correlation to pediatrics is limited.11 The Wilson Risk score also is used in the adult population. It describes weight, head, neck, and jaw movement, receding mandible, and “buck teeth” as predictive risk factors for difficult airways. Risk factors reported in the literature, which are associated with a higher incidence of difficulties with airway management, include age younger than 1 year, American Society of Anesthesiologists physical status III and IV, Mallampati score of III or IV, obesity (body mass index ≥ 35), and patients undergoing oromaxillofacial surgery, ENT surgery, or cardiac surgery.12 Given that no specific test or feature has been shown to have 100% sensitivity and specificity, especially in the pediatric population, the current trend in clinical practice is to combine the various scoring systems in an attempt to improve their predictive value.13
Pediatric airways can be even more challenging in the setting of trauma, when blood, vomit, or excess secretions can obstruct direct visualization of the airway. Patients younger than 1 year of age are at higher risk of difficult airways and difficult intubations.6,14 However, a difficult airway should always be anticipated in pediatric patients with baseline craniofacial abnormalities.14 This includes a variety of syndromes, such as Pierre Robin, Down, Treacher Collins, Cornelia de Lange, and Goldenhar. Other anatomic considerations that may be associated with pediatric airway difficulties include macroglossia, midface hypoplasia, and cleft palate. Additionally, a history of a difficult intubation or a difficult airway in the past should prompt expert consultation (i.e., pediatric anesthesia).7,9,15
In the setting of facial trauma, the potential for a difficult airway should be considered. Inability to open the mouth because of pain will make accessing the airway problematic. Loose teeth, blood in the airway, and pharyngeal edema can increase the risk of possible airway obstruction.7 Cervical spine trauma also is noteworthy in that pediatric patients in cervical spine collars often have limited mobility, compromizing visualization of the airway. Patients with possible neck trauma should have the head and neck in a neutral position to minimize the risk of further injury.6
An alternative to traditional endotracheal intubation and direct laryngoscopy is a laryngeal mask airway (LMA). The LMA is a supraglottic device that can be placed blindly. Although an LMA is not a definitive airway, LMAs have an overall low complication rate.16 This is an option when intubation is not possible and bag/mask is ineffective.17 The LMA is teardrop-shaped and has an inflatable cuff.5,8 It is placed in the hypopharynx and sits above the glottis. Air flow is directed through the glottis and then into the lungs. LMAs are available in a variety of sizes, from infants to teenagers. (See Table 2 and Figure 4.)
Pulse oximeters measure hemoglobin oxygen saturation via an external probe. The light of two varying wavelengths passes through the skin, and the difference in absorbance by arterial blood of these two wavelengths by the photodetector within the pulse oximeter is used to calculate the level of oxygenation.13 Hypoxemia is assessed more readibly by monitoring devices, such as pulse oximetry, than by physical exam alone. Therefore, all children requiring airway management should have continuous pulse oximetry in place as airway issues are being addressed. After the pediatric airway is secure, it is imperative that oxygen saturations are monitored closely.18 It is well documented that hypoxemia is often a precursor to cardiac arrest.4 Pulse oximetry is a simple method of continuously measuring oxygen saturations in a sedated and/or intubated patient.18 Most pulse oximeters give feedback about the patient’s heart rate as well.
End-Tidal Carbon Dioxide Monitoring
Capnography, or continuous monitoring of expired carbon dioxide (CO2), is noninvasive and can provide an early indication of inadequate ventilation.19 Capnography uses infrared technology to measure the amount of CO2 exhaled.13 Additionally, capnography provides a visual depiction of CO2 exhalation over time, which gives insight regarding ventilation and respiratory function. The International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science as well as the American Heart Association updated their guidelines for both Adult and Pediatric Advanced Life Support in 2010 to include recommendations for routine use of quantitative waveform capnography for both intubation and during CPR. Unfortunately, the routine use of capnography has not been implemented as recommended.20 Specifically, in pediatric patients, capnography has several advantages. It has been shown to be superior in detecting ETT displacement. Also, it has been shown to be superior to physical exam at identifying apnea and gives the earliest warning signs of ETT obstruction and esophageal intubation.19,21,22
Rapid Sequence Intubation: Goals
The goal of rapid sequence intubation (RSI), a sequential process of preparation, sedation, and paralysis, is to facilitate safe emergency tracheal intubation. Pharmacologic sedation and paralysis are used in rapid succession to perform tracheal intubation quickly and effectively. RSI is an airway management technique that induces immediate unresponsiveness (induction agent) and muscular relaxation (neuromuscular blocking agent), and is the fastest and most effective means of controlling the emergency airway. Tracheal intubation is indicated in the following clinical scenarios: respiratory failure due to lack of appropriate oxygenation; respiratory failure due to lack of appropriate ventilation; lack of neuromuscular respiratory drive/impending airway compromise; and lack of airway protective reflexes.4,7 In the pediatric population, most of the common indications for intubation are trauma and primary respiratory failure. Examples include cardiac arrest, traumatic brain injury, and status epilepticus. Additionally, in the setting of trauma, patients with a Glasgow Coma Scale score of 8 or less should be evaluated for immediate airway protection and intubation.2 The establishment and maintenance of a definitive airway is an essential skill for the pediatric emergency medicine and emergency medicine provider.4
The most common route of intubation in the emergency setting is the oral route, namely direct laryngoscopy, which will be referenced most commonly throughout this article. Other methods and devices used in RSI and artificial airways include nasal intubation, video-assist methods (i.e., GlideScope and C-MAC), and surgical airways (surgical cricothyrioidotomy, needle cricothyroidotomy and tracheostomy). Surgical airways are beyond the scope of this article.
Before attempts are made to establish an airway, all children should be appropriately preoxygenated with high-flow, 100% oxygen prior to intubation. The goal is to prevent complications during the apneic phase of RSI. Without this practice, nearly one-third of patients will have a desaturation episode to less than 90%.1
Children have a higher metabolic rate and resultant oxygen requirement than adults. Poor ventilation and increased demands can result in hypoxia. Even transient episodes of hypoxia or desaturation can have devastating consequences. Untreated hypoxia often is a precursor to cardiac arrest in children.4 Other complications from hypoxia during RSI include hemodynamic instability, dysrhythmias, and anoxic brain injury.
Preoxygenation with 100% for about three minutes via either a nasal cannula,23 a bag-valve-mask, or a non-rebreather mask can decrease the chance of rapid desaturation.24 With preoxygenation, an apneic child is much less likely to have significant desaturation during RSI.25,26 In addition, apneic oxygenation in pediatric patients shows similar results to adult apneic oxygenation. Vukovic et al showed that apneic oxygenation is an easily applied intervention associated with decreases in hypoxemia during pediatric ETI. Nearly 50% of children not receiving apneic oxygenation experienced hypoxemia.27
Rapid Sequence Intubation: Sedation Options
The goal of RSI, which is the cornerstone of airway management, is to secure the airway safely with as few attempts as possible, while minimizing pain. In general, this is a procedure that can be done outside of the operating room and independent of anesthesia.28 Two primary classes of medications are used for RSI.
The first class of medications is sedatives, which are used to mitigate the physiologic consequences of intubation. (See Table 3.) The second class is paralytics. These two classes of medications will be discussed in further detail.
Etomidate is an imidazole, a non-barbiturate, and gamma-aminobutyric acid (GABA)-mediated sedative hypnotic. It has very potent sedative features, but no analgesic properties. One key feature is its very minimal effect on heart rate and blood pressure. Also, apnea is noted significantly less often with etomidate, as compared to propofol or barbiturates. The cerebral perfusion pressure is maintained during etomidate administration, while the intracranial pressure (ICP), cerebral blood flow, and metabolic rates are decreased. Because etomidate does not release histamine, allergic reactions are seen rarely.29 Etomidate has a relatively quick onset of action of 10 to 15 seconds, with a short sedation duration of 3 to 12 minutes. The dose for pediatric RSI that has been shown to be safe is 0.3 mg/kg IV.29-32
Because hemodynamic instability is not a significant consequence of etomidate, its use is favorable in patients who are experiencing decompensated shock, particularly those in a trauma setting who have sustained a large volume of blood loss. Both Sokolove et al33 in their retrospective review and Zuckerbraun et al30 in their prospective study found that hypotension after induction with etomidate was uncommon.34 Further, the neuroprotective properties of etomidate make it a popular choice for RSI of pediatric patients who have sustained a traumatic head injury. However, it is important to note that etomidate has no analgesic properties; thus, in the global management of a trauma patient, additional therapies may be warranted in the peri-intubation setting.
Early studies have reported myoclonus and vomiting as potential side effects of etomidate. However, more recent studies found these effects to be uncommon, particularly when etomidate was used in conjunction with a paralytic for RSI.30,35,36 Injection site pain and thrombophlebitis are concerns if etomidate is administered through a peripheral vein.13 A more concerning potential disadvantage of etomidate is its suppression of adrenal cortical function by inhibiting 11-β-hydroxylase. In light of this potential risk, one should consider other sedative agents for RSI in patients at risk for adrenal insufficiency, including those presenting in septic shock, as etomidate is contraindicated.37 The use of etomidate in pediatric trauma patients is not delineated as clearly in the literature. However, a recent survey of pediatric trauma programs found that its use is relatively common.38
Ketamine is a dissociative anesthetic that interacts with the N-methyl D-aspartate (NMDA) receptors. It is also an α- and β-adrenergic receptor agonist, and blocks the reuptake of catecholamines.39 Clinical effects include anesthesia, analgesia, amnesia, and suppression of fear and anxiety.39 Ketamine is unique in that it possesses both analgesic and amnestic properties.40 The sympathomimetic effects of ketamine on the cardiovascular and respiratory systems result in increased heart rate, blood pressure, and bronchodilation. Although ketamine administration results in increased salivary and tracheobronchial secretions, airway protective reflexes such as coughing, sneezing, and swallowing are maintained.39 Ketamine is highly lipid soluble; thus, it crosses the blood-brain barrier quickly, leading to a rapid onset of action. The onset of sedation with IV dosing is 45 to 60 seconds, with a duration of 10 to 20 minutes.41 The RSI dose is 1-2 mg/kg IV.13
Because of its bronchodilatory effects, ketamine is an ideal sedative for RSI in patients with severe bronchospasm. Because of the sympathomimetic properties of ketamine, it also may be useful for patients in shock. Unlike etomidate, ketamine may be considered in patients with septic shock, because it does not cause adrenocortical suppression. However, every effort should be made to reverse hypovolemia and hypotension prior to RSI in these patients. Ketamine’s hemodynamic stability and anticonvulsant properties may benefit the hypotensive or normotensive patient with traumatic brain injury.42
Early studies of ketamine suggested that it was contraindicated in patients with traumatic brain injury because of the side effect of increased ICP. More recent studies suggest that the evidence for this is minimal.43 Bar-Joseph et al further disproved this notion, finding that ketamine is safe for use in patients with traumatic brain injury.44 Similar to early studies relating ketamine to increased ICP, ketamine has been thought to cause mild increased intraocular pressure.45 At doses commonly used for RSI, this has been found not to be the case.46 Another potential side effect of ketamine is excessive salivation, for which atropine pretreatment previously was recommended. In their prospective observational study, Brown et al found that this is a rare complication of ketamine at RSI doses, and the routine use of atropine was not warranted.47 Other side effects of ketamine administration include transient oxygen desaturations, laryngospasm, tachycardia, emesis and emergence reactions, and myoclonic jerks. These effects are not seen commonly in the setting of ketamine use for RSI.
Propofol is a highly lipid soluble agent that may work by decreasing dissociation from GABA receptors in the brain and potentiating the inhibitory effects of the neurotransmitter. It is a non-barbiturate sedative hypnotic anesthetic agent that causes sedation by direct suppression of brain activity, while the amnestic effect is due to interference with long-term memory creation.48 However, it does not provide any analgesia. Propofol contains egg lecithin and soybean oil, so it is absolutely contraindicated in patients with an egg allergy. However, fewer allergic reactions have been reported with newer preparations of the medication. The initial bolus dose is 1.5-3 mg/kg IV, with extremely rapid onset, generally in 15 to 45 seconds, and a duration of action of five to 10 minutes. Studies have suggested a slightly longer time to peak effect in children.49 Infants also are noted to require higher doses than older children.
Because of its suppression of sympathetic activity, propofol causes both vasodilation and myocardial suppression. Therefore, its use as an RSI agent should be limited to those patients who are hemodynamically stable. Although it does have neuroinhibitory effects that make it a good RSI choice for patients in status epilepticus, the associated drop in mean arterial pressure (MAP) and subsequent cerebral perfusion pressure (CPP) limit its use in patients with traumatic brain injury. Propofol has been shown to inhibit bronchoconstriction, and it can be useful for RSI in patients who have bronchospasm. It also has been shown to have modest antiemetic properties. Respiratory events, such as central apnea and hypoxia, are not uncommon and should be expected. These occur most commonly with bolus doses. The safety profile of propofol has been well studied in pediatrics, outside of the operating room.50 Serious events, such as cardiac arrest, unplanned anesthesia consult, and increased level of medical care, are noted to be minimal when propofol is used in healthy children.51
When given in high doses for a prolonged period of time, propofol may be associated with a condition known as propofol infusion syndrome (PRIS). This syndrome is characterized by severe lactic acidosis, rhabdomyolysis, acute renal failure, hyperlipidemia, recalcitrant myocardial failure, hypotension, bradycardia, and death. Proposed risk factors for developing PRIS include head injury, airway infection, young age (< 18 years), low carbohydrate intake/high fat intake, inborn errors of fatty acid oxidation, high doses of propofol for more than 48 hours, and combined use of catecholamine vasopressors and/or glucocorticoids.43,44 Serum lactate and creatine phosphokinase levels should be monitored closely during propofol infusions.52
Midazolam is a short-acting benzodiazepine that, like propofol, binds the GABA receptor. It has amnestic, anxiolytic, and anticonvulsant properties. The anticonvulsant effect lends itself as a sedative for RSI for patients in status epilepticus. Also, similar to propofol, midazolam decreases systemic vascular resistance, resulting in hypotension; therefore, it should not be used in hemodynamically unstable patients. Respiratory depression and apnea are side effects seen with midazolam use, making the preoxygenation prior to paralytic administration less effective. These side effects are augmented when midazolam is combined with other sedative agents, particularly opioids. Because of the noted side effects, midazolam usually is not recommended as a first-line sedative agent for RSI. The induction dose is 0.1-0.3 mg/kg IV, with an onset of action of 60 to 90 seconds that lasts for 15 to 30 minutes.
Fentanyl and morphine are narcotics that also can be used for sedation during RSI. Unlike several of the other sedatives, these have analgesic properties that can be useful in the trauma setting. Morphine is associated with greater histamine release, resulting in pruritus, while fentanyl can be associated with chest wall rigidity when rapidly infused. Both fentanyl and morphine can cause hypotension, so they should be given with caution. The RSI induction dose of fentanyl is 1-5 mcg/kg IV and morphine is 0.1-0.2 mg/kg IV. The onset of action of fentanyl is 30 to 60 seconds as compared to morphine, which usually takes effect in five to 10 minutes. Fentanyl duration is generally 30 minutes as compared to the longer duration of morphine of three to five hours. For a summary of the sedatives used in RSI, see Table 3.
Neuromuscular blocking agents provide muscle paralysis to facilitate endotracheal intubation. They should be used in conjunction with a preceding sedative to achieve full RSI effect.
The two main classes of neuromuscular blocking agents are depolarizing and nondepolarizing. Both induce motor paralysis by inhibiting acetylcholine stimulation of nicotinic receptors at the neuromuscular junction.
Succinylcholine is the only depolarizing paralytic agent that is used commonly in pediatric RSI. Its rapid onset and short duration of action make it an ideal neuromuscular blocking agent for RSI in patients with presumed difficult airways. Succinylcholine is distributed rapidly into an enlarged volume of extracellular fluid in younger patients, leading to the necessity of higher doses for RSI.53 For children younger than 2 years of age, the recommended dose is 2 mg/kg IV. The dose is 1 to 1.5 mg/kg IV for children older than 2 years of age. Bradycardia can be seen with administration of succinylcholine, and it is seen more commonly in younger children. Asystole also can be seen with repeated doses of succinylcholine; however, administration of multiple doses is rare in RSI. To combat these effects, it has been recommended that children younger than 5 years of age, and older children who require a second dose of succinylcholine, be pretreated with atropine; recently, however, this practice has been called into question.54
Additional adverse effects associated with succinylcholine include hyperkalemia, which results from the widespread state of muscle depolarization. Therefore, administration is contraindicated in patients with preexisting hyperkalemia, malignant hyperthermia, extensive crush injuries with rhabdomyolysis, within 48-72 hours after burns or acute spinal cord injury, as well as in patients with muscular dystrophy.55 The Food and Drug Administration recommends caution in the use of succinylcholine in pediatrics. There have been reports of acute rhabdomyolysis with hyperkalemia followed by ventricular dysrhythmias, cardiac arrest, and death after the administration of succinylcholine to apparently healthy children who were subsequently found to have undiagnosed skeletal muscle myopathy, most frequently Duchenne muscular dystrophy. Relative contraindications include administration in patients with increased ICP and intraocular pressure.55
Paralytics in this category include rocuronium, vecuronium, and pancuronium. Rocuronium is the most commonly used for pediatric RSI, because it has the shortest onset of action of less than one minute.56 It acts on the nicotinic cholinergic receptor and has a shorter duration of action than the other nondepolarizing agents.57 It has minimal cardiovascular side effects, with only a minimal reported incidence of tachycardia and mild hypertension.57 The pediatric RSI dose is 0.6-1.2 mg/kg IV.58 Average time to onset for vecuronium is 120-180 seconds, and the duration of action is 45-60 minutes. It generally is not used for RSI unless succinylcholine is contraindicated and rocuronium is unavailable. The recommended RSI dose is 0.15-0.3 mg/kg IV.
Rocuronium is the most widely used neuromuscular blockade agent in a recent prospective observational cohort study across 19 pediatric intensive care units in North America. In 92% of tracheal intubation, the majority used rocuronium (64%), followed by vecuronium (20%). Succinylcholine was rarely used (0.7%).59 The reason for this preference may be the risk of undiagnosed myopathies, which may result in an adverse event with the use of succinylcholine.
Pancuronium, the longest acting paralytic, has a duration of action of 60-90 minutes and has the slowest onset of action, two to five minutes. The use of pancuronium typically is reserved for maintenance of paralysis after RSI. The recommended RSI dose is 0.05-0.1 mg/kg IV for infants and 0.05-0.15 mg/kg IV for children.58 (See Table 4.)
Complications of Pediatric Intubation
RSI has been shown to be well within the scope of practice and training of pediatric emergency medicine staff as well as adult emergency medicine staff. Across training centers, RSI may be performed by attending staff, pediatric emergency medicine fellows, pediatrics residents, or emergency medicine residents. Specifically, first-attempt direct laryngoscopy success rates have been shown to be about 77% for pediatric emergency medicine fellows and emergency medicine residents. Pediatrics residents have a slightly lower success rate at about 50%. Overall, the first-attempt success rate has been shown to be about 80-90%. This overall rate includes the success rate of direct laryngoscopy with attending staff backup. The slightly lower success rate for pediatrics residents may be due to the emphasis on airway management in pediatric emergency medicine fellowship training and emergency medicine residency. Additionally, the difficulty of the airway, as previously discussed, is largely predictive of first-attempt success.60
Historically, direct laryngoscopy (DL) has been the standard for pediatric airway management. In a recent study, researchers used data from the National Emergency Airway Registry (NEAR) to compare success rates of DL and video laryngoscopy (VL) in pediatric patients while controlling for predictors of difficult airways.
First-pass success was significantly higher in the VL group (84.0% vs. 74.5%). Multivariable regression, which controlled for confounders and difficult airway characteristics, showed that odds of first-attempt success were higher with VL than DL (even when augmented by laryngeal manipulation or use of a bougie). In a subgroup of patients younger than 2 years of age, the odds of first-pass success were two times higher with VL. The most common adverse event was hypoxia (15.8%), and the incidence did not differ between groups.61
One of the most common technical complications of RSI is a mainstem, or endobronchial, intubation. Achieving the appropriate ETT position can be challenging for the intubating provider because the pediatric trachea is much shorter in length than an adult’s, as previously discussed. When intubated in the ED, about 30% of children will likely have an ETT that is placed incorrectly. There also is some evidence that female patients have a higher rate of misplaced ETT compared to males, possibly because of the shorter distance between the lips and the carina.62 Female patients also have a higher rate of first-attempt missed intubations, likely for similar reasons.56 Tracheas can be as short as 5 cm in neonates. Younger age and lower weight are associated with a higher rate of misplaced ETT. Additionally, the ETT position is often easily changed by subtle alterations in head position, such as flexion and rotation.63 This often leads to overventilation of the intubated side and hypoventilation and atelectasis of the contralateral side. This can lead to severe hypoxia if not recognized promptly.63,64
The ETT should be advanced as little as 2.5 cm in neonates, because the distance between the glottis and the carina can be as little as 5 cm.63 In older children, advance only enough for the cuffed ETT to disappear. Most commercial ETTs have an indicator mark that helps denote proper positioning or a visual cue for proper placement. However, generally, most EETs can be secured at the gum based on the formula: ETT size × 3.62
Colorimetric CO2 monitoring devices are helpful adjuncts to suggest proper intubation, but this does not ensure correct placement. Generally, colorimetric monitoring devices have been popular during RSI because they are fast, easily portable, highly sensitive, and do not require a monitor source.65 However, they now are being largely replaced by end-tidal capnography for a variety of reasons, including improved accuracy and the ability to measure ventilation.19
Most airway lengths vary greatly in size, so one should not rely completely on any one formula for depth of insertion. It is common practice to observe for adequate chest rise as well as equal breath sounds. Obtaining a chest radiograph after intubation is necessary and is the most accurate method of assessing ETT position.
Pneumothorax and Aspiration
Although rare, two physical complications of RSI are pneumothoraxes and aspiration events. Pneumothorax results from air entering the potential space between the visceral and parietal pleura. In the setting of trauma, an asymptomatic, simple pneumothorax can progress to a tension pneumothorax with bag-valve-mask and positive pressure ventilation.4 Overall, pneumothoraxes are reported to occur in less than 1% of RSI encounters.56 Aspiration generally is defined as food or food particles in the airway along with concerning sequelae: change in chest radiograph indication of aspiration or change in oxygen requirement.66 Although these events are rare in the setting of RSI, they must be recognized promptly and treated appropriately.
Specific Pediatric Considerations: Trauma
Injuries and trauma occur frequently in pediatric patients. However, a number of unique factors should be considered that represent key differences between the management of adults and children. In the setting of blood loss, children remain normotensive much longer than adults. Further, because cardiac output in children is so dependent on their ability to increase their heart rate, procedures and medications that cause bradycardia can have significant deleterious effects on tissue perfusion.67 The pediatric airway, as discussed previously, has characteristic anatomic differences that put the patients at increased risk for airway obstruction, and has limited visualization during advanced airway maneuvers.
One notable trauma consideration involves the protection of the cervical spine. Although pediatric cervical spine trauma is uncommon, it can be life-threatening if unrecognized. Most cervical spine injuries and neck trauma are due to either blunt or penetrating trauma. Motor vehicle crashes, falls, and nonaccidental trauma are the most common etiologies of blunt trauma. Penetrating trauma leading to cervical spine injury is uncommon in children, but may be caused by gunshots, dog bites, and other sharp objects. As emphasized previously, the specific goals of RSI in the setting of cervical spine trauma are to maintain a patent airway with adequate ventilation while supporting the structures of the spine. Pediatric patients with cervical spine trauma often have subtle neurologic findings, thus reassessments must be frequent and an index of suspicion must be high. Clinical signs, such as neurologic dysfunction, audible stridor, subcutaneous emphysema, hoarseness, and neck hematomas, are concerning for possible neck trauma. This also should raise concerns for possible cervical spine injury and the potential for a difficult airway. Oral intubation is the preferred method for securing an airway in the setting of cervical spine injury. However, this should be performed by a skilled provider and only with preparation for a surgical airway if needed. Care should be taken not to hyperextend the neck. The larynx, esophagus, and trachea are anterior, and more likely to be injured during the intubation process.7
In addition to the previously noted pediatric considerations, it is important to note that RSI is not without inherent risk for adverse events. These risks are compounded in a trauma setting. One must consider the potential for foreign objects, such as teeth, vomitus, blood, and other debris, in the airway, obstructing visualization of the vocal cords. Trauma patients must be assumed to have a full stomach; pain, additional injuries, and airway maneuvers that stimulate the gag reflex can lead to vomiting and subsequent aspiration. Consider placing an orogastric tube to aspirate stomach contents prior to attempting intubation, especially in the setting of prolonged bag-valve-mask ventilation. Additional adverse events include the need for multiple attempts, right mainstem bronchus, or esophageal intubation, as discussed previously.
Given the specific pediatric anatomic and physiologic differences, as well as the potential for adverse events during RSI in a trauma patient, careful consideration should be given to the management of the pediatric airway. The decision to intubate children in a trauma setting should not be taken lightly, and providers must consider the potential side effects of the medications administered. It is appropriate to choose an opiate as a sedative, as these agents provide pain management, which ultimately will decrease morbidity and mortality.68 It is important to note, however, that both fentanyl and morphine can result in hypotension, which may compound the hemodynamic effects of extensive blood loss. Both ketamine and etomidate provide sedation with minimal hemodynamic effects and, subsequently, are the most favorable sedatives for RSI in the trauma setting. Further, etomidate may have a neuroprotective effect for patients who have sustained a traumatic brain injury. The ideal agent for neuromuscular blockade in the trauma RSI setting is one that has rapid onset, short duration of action, and minimal side effects. Of those available, succinylcholine and rocuronium are used most frequently. A recent Cochrane Review article compared both medications and found that succinylcholine was a superior RSI agent.69 While succinylcholine produced more favorable intubation conditions, there are a great deal of contraindications to its use, which must be recognized.
The pediatric airway differs greatly from the adult airway. It is shorter and more anterior, which often can make direct visualization challenging. Assume difficult airways in children with significant head, face, or neck trauma. This includes children with cervical spine immobilization. Additionally, children with craniofacial abnormalities and syndromes are at higher risk for difficult airways and difficult intubations. Hypoxia is a precursor to cardiac arrest in children. Preoxygenation is necessary prior to securing an airway. When properly sized, OPAs and NPAs are helpful adjuncts to prevent upper airway obstruction. The goals of rapid sequence intubation are to secure an airway emergently and safely. There is a variety of sedation options in pediatrics to achieve this goal. Nondepolarizing paralytic agents, such as rocuronium, are increasing in popularity in pediatric emergency medicine because of their shorter half-life and more favorable safety profile. Complications of RSI, such as missed intubations and multiple airway attempts, should be considered carefully. Consultation with subspecialists also should be considered.
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