Rapid sequence intubation is a cornerstone of emergency medicine, and in the pediatric emergency medicine world, the frequency with which we intubate our patients is less compared to our adult EM counterparts. Furthermore, the pediatric patient is considered a “difficult airway” by virtue of being a child, and their physiology gives them less reserve at baseline. Let’s review the most popular medications used in RSI.
Recommended as a premedication in young infants and children, atropine has been given to prevent reflex bradycardia that occurs during intubation due to reports of a more pronounced vagal response in kids compared to adults. It has been recommended for consideration in certain pediatric populations deemed at risk, such as kids <1 year, those receiving succinylcholine under 5 years of age, and those that are bradycardic before intubation. It may also be beneficial before a second dose of succinylcholine. However a study performed by Fastle and Roback in 2004 demonstrated that bradycardia occurred equally in children who received atropine and those who did not. This data supports that atropine may not need to be routinely used for pediatric intubations.
Lidocaine has been recommended for consideration in patients at risk for increased intracranial pressure, as the act of intubating or manipulating the airway can cause increases in intracranial pressure. Data however, has been equivocal; some studies show no effect with lidocaine, while others show some reduction in ICP compared to placebo. In order to take full effect, it is recommended to give lidocaine at least 2-3 minutes before RSI and intubation, and depending on the acuity of your patient, this may not be time that you can afford. It may also be helpful in reducing bronchospasm when given as pre-medication in status asthmaticus.
Etomidate is a good choice for patients with hemodynamic instability or patients with head trauma, because it does not cause any hypotension or increased intracranial pressure. It has previously shown to cause adrenal dysfunction in patients receiving etomidate as a continuous infusion, but this has also been documented in patients who receive a single dose. In an article published in AEM by Schenarts, a prospective randomized control trial showed a decrease in the cosyntropin stimulation test at 4 hours in adult patients who received etomidate for RSI, and their cortisol levels, although decreased, were still within normal range. The results of the cosyntropin stimulation test normalized within 12 hours of administration of etomidate. I have not found any study that demonstrated a clinically relevant response to this suppression in patients who received etomidate for RSI. Etomidate is still increasing as a preferred induction agent, so one must simply use caution when choosing etomidate for patients with sepsis. Many experts will unequivocally use ketamine if sepsis is on the differential diagnosis. The jury is still out. Finally, etomidate has also been shown to potentially lower the seizure threshold.
The workhorse of emergency medicine, ketamine causes a catecholamine release that is beneficial for patients in status asthmaticus (leads to bronchodilation). It was a long held belief that ketamine caused increases in intracranial and intraocular pressure. This was mostly demonstrated in animal models and is not likely to be clinically relevant.
Opiates can cause hypotension as well and are not always as reliable at inducing unconsciousness in patients. Fentanyl in higher doses may be used in select scenarios (neonates with congenital heart disease, heart disease with septic shock) given it’s cardio-neutral activity. Doses are often quite high in these cases – 4 mcg/kg.
Versed is most commonly used in this class, given it has the quickest onset and shortest duration. Another benefit of Versed in particular is that it is has multiple routes of administration. However it can cause hypotension, which may not make it the best choice in the hemodynamically unstable patient. Additionally, benzodiazepines have been shown to have variable effectiveness at inducing unconsciousness in pediatric patients with a variable dosing range; this may make them a suboptimal choice for induction.
A depolarizing neuromuscular blocker, this has been the most commonly used paralytic for RSI in pediatric patients due to its quick onset (30-60 seconds) and short duration (less than 15 minutes). Succinylcholine can cause an increase in serum potassium (usually only 0.5-1 mEq/L) and because of this should be avoided in patients with renal failure, suspected hyperkalemia or known potassium >5.5 mmol/L, muscular dystrophy or crush injury with prolonged entrapment. It should also not be used in patients with crush injuries or burns >48 hours old because these patients have upregulation of the postsynaptic acetylcholine receptors after their injury.
The nondepolarizing neuromuscular blocker with the fastest onset (60-90 seconds) and the shortest duration (30-45 minutes) of the class. It does not cause an increase in ICP or in serum potassium levels. In a study by Mazurek of 26 patients, half of whom received rocuronium and half of whom received succinylcholine for RSI (all other pretreatment/induction measures remained constant), there was no significant difference in onset of apnea and no significant difference in time to completion of intubation between the two groups. Despite succinylcholine historically being used more commonly, rocuronium use has been steadily increasing over time.