Does sugammadex mean the end of suxamethonium for rapid sequence induction?
The answer: No, not by a long shot. Let me explain...
Suxamethonium (succinylcholine) is a depolarising muscle relaxant and often the first choice for muscle paralysis when a rapid sequence induction (RSI)1 is needed. In addition to working quickly suxamethonium has a very rapid offset. For both anaesthetist and patient these are very desirable characteristics, although they come at a price. The price is suxamethonium's long list of side effects, ranging from minor to life threatening.2 Were it not for it's life-saving fast-kinetics, suxamethonium's use in modern anaesthesia would no longer be justifiable.
This article is part two in a three part series beginning with 'If sugammadex is the answer, what is the question?'.
When rocuronium was first introduced in the 1990s it was met with excitement.3 Rocuronium's claim to fame was a very fast onset of action. Because it was less potent than other non-depolarising muscle relaxants of its generation (atracurium & vecuronium) a larger dose was required to achieve the same level of muscle paralysis. This dose created a large concentration gradient between plasma and the neuromuscular junction resulting in a faster onset of action. By giving a very large dose of rocuronium the anaesthetist could produce acceptable intubating conditions within 60 seconds, creation the first reliable modified rapid sequence induction.
Unfortunately the result of using such a large dose of rocuronium is a prolonged blockade. Even at lower doses (0.6 mg/kg 2x ED95) rocuronium produces a block that lasts at least five times longer than suxamethonium. At the 1.2 mg/kg (4x ED95) modified-RSI-dose of rocuronium the block duration stretches out even longer, reaching the duration of pancuronium. In the event of being unable to intubate, or worse unable to ventilate, prolonged blockade is disastrous. At this point rocuronium only provided half a solution for the replacement of suxamethonium.
The rapid sequence induction, as the name suggests, involves very fast induction of general anaesthesia with rapid intubation of the trachea in order to protect the airway quickly, often in emergency situations. ↩
Most significantly, anaphylaxis, hyperkalaemia and malignant hyperthermia, and also including suxamethonium apnoea and various cardiac arrythmias. Not to mention the 'minor' side effect of feeling run over by a truck after recovering from a suxamethonium paralysis. Suxamethonium adverse effects - wikipedia ↩
Hunter JM. Rocuronium: the newest aminosteroid neuromuscular blocking drug. Br J Anaesth. 1996 Apr;76(4):481-3. ↩