Succinylcholine in Pediatric RSI

We pediatricians have been a little unfair to succinylcholine. As the sole depolarizing paralytic, and the one with the fastest on (30-60 seconds) and off (4-6 minutes) times, it is an essential medication to have in our RSI arsenal.  Many myths of its contraindications have been perpetuated.  When do we really need to avoid it in the pediatric patient?

Victims of crush or burn injuries?

The potential development of hyperkalemia with succinylcholine administration is not an acute concern for crush or burn injury victims.  Remember, the problem is that extensively damaged skeletal muscle responds by up-regulating its acetylcholine receptors, and it’s the presence of these increased receptors that potentiates the release of intracellular potassium. However, the upregulation of these receptors is a process which takes hours – well over 24 hours – not minutes.  The injury victim in rehab who acutely decompensates and requires RSI should receive only non depolarizing paralytics, but succinylcholine can be safely used in the immediate resuscitation of victims of crush or burn injuries.

Children with head injury?

Pediatric trauma victims not uncommonly suffer head injury and the concern for potential increased intracranial pressure is high. Succinylcholine was found to increase the intracranial pressure of a few animal models and in some smaller studies looking at patients with known brain tumors – but this has not translated to the pediatric trauma bay very well. Unless there are other concerns about the use of succinylcholine for a particular patient, isolated head injury should not be a contraindication to its use.

Children with potential neuromuscular disorders?

The potential for developing malignant hyperthermia and/or hyperkalemia with succinylcholine is very real in these patients.  School-age children and older will already carry a known diagnosis (or at the very least, have an obvious neuromuscular abnormality) and it is a straightforward decision to avoid succinylcholine in this group.  Unfortunately, the diagnosis may not be known or suspected in the very young patient.  Caution should be exercised in young children (toddlers and under) who have any concern for developmental delay.  The most common muscular dystrophies – Duchenne and Becker – are X-linked recessive, by the way, so you could be fancy and use non depolarizing agents in all very young boys.

Myasthenic crisis?

The problem in myasthenia gravis is a little different than with other neuromuscular disorders, because rather than upregulating acetylcholine receptors, these patients have fewer receptors.  As a result, succinylcholine is difficult to use -- though it shouldn’t cause hyperkalemia or cardiovascular instability, higher doses are required to achieve paralysis and the effect will be prolonged.  Given its unpredictability in this regard, use of a non depolarizing agent for RSI in the setting of myasthenic crisis makes the most sense.

-- Lisa McQueen MD

References:

Levitan R.  “Safety of succinylcholine in myasthenia gravis.” Annals of Emergency Medicine 2005;45:225-56.

Walls, RM (ed).  Manual of Emergency Airway Management. 3rd ed. Philadelphia: Lippincott Williams & Wilkins, 2008.

Zelicof-Paul, A et al.  “Controversies in rapid sequence intubation in children.”  Current Opinions in Pediatrics 2005;17:355-62.