An Easier Way to Remember if Succinylcholine is Safe for Your Patient.

Jonathan St. George MD
4 min readNov 21, 2017

Hint: if they have Guillain-Barre Syndrome it’s not…

Succinylcholine (Sux) is a depolarizing skeletal muscle relaxant. It combines with the cholinergic receptors of the motor end plate to produce sustained depolarization and paralysis, and it’s rapid onset makes it an effective agent for use in rapid sequence intubation (RSI).

This mechanism of action however, also makes it a potentially dangerous drug in a subset of patients who need RSI because of its potential to cause hyperkalemia, subsequent cardiac arrhythmias, and death.

But if remembering that long list of specific contraindications to Sux seems intimidating and inclines you to avoid it as your go to RSI paralytic, don’t give up. Sux remains one of the safest, most useful, and reliable agents for RSI. And with only a few exceptions, most of the contraindictions on the list are related in some way to hyperkalemia. So instead of trying to memorize (and then worrying about if you will be able to recall) that long list of contraindications during critical moments, you can organize that list into two main categories:

1. Those who have a disease that causes hyperkalemia.

2. Those who have a disease that may cause an exaggerated response to Sux.

Placing the contraindications within these two catogories makes it easier to remember (and thus recall) under the stress of managing a rapidly evolving airway. Let’s get into it.

Those who have a disease that causes hyperkalemia.

Typically Sux administration will raise a person’s potasium about 0.5–1.0 mEq/L. This isn’t serious for someone with a potassium of 4.0 mEq/L, but it could be enough to kill someone…

Jonathan St. George MD

Physician, Educator, Writer. “It's not what you look at that matters, it's what you see.” - hdt