Rapid sequence induction: suxamethonium or rocuronium?

Drs Cadamy and Booth condemn the use of rocuronium at rapid sequence induction (RSI) and advocate a propofol/alfentanil regimen as an alternative to thiopentone/suxamethonium (Anaesthesia 1999; 54: 817). Although a number of studies involving healthy subjects have shown that tracheal intubation can indeed be performed without neuromuscular block, there is no evidence that such propofol/opioid techniques are safe in those elderly and unfit patients undergoing RSI who will be less tolerant of the likely concomitant hypotension. I believe that the emergency patient whose trachea proves difficult to intubate runs a greater risk of hypoxaemia and aspiration from waning suxamethonium block as opposed to continuing profound nondepolarising block with rocuronium. A partially paralysed patient bucking and straining will consume large amounts of oxygen. Huge increases in intragastric pressure have been measured [1]. I suggest that partial recovery from suxamethonium has the potential to turn a difficult intubation into a failed intubation, and ‘can't intubate, can ventilate’ into ‘can't intubate, can't ventilate’. The timecourse of recovery from suxamethonium block is of course unpredictable [2]. Benumof and colleagues have warned against relying on recovery from suxamethonium to enable a patient to breathe adequately before critical desaturation occurs [3]. The lack of concordance in the practice of RSI and management of failed intubation has been highlighted recently [4]. Adoption of rocuronium at RSI means that the anaesthetist is committed to maintaining oxygenation by positive pressure ventilation. However, sustained optimal conditions will be afforded for unhurried successful tracheal intubation or placement of a Combitube/LMA. The guaranteed absence of pharyngeal and laryngeal reflexes must surely increase the likelihood of safe airway management without provocation of vomiting/regurgitation. Rocuronium is an immunologically clean drug, devoid of the catalogue of potential complications peculiar to suxamethonium. Randomised trials of suxamethonium vs. rocuronium in elective and emergency patients undergoing RSI have confirmed that rocuronium 0.1 mg.kg−1 provides intubating conditions clinically equivalent to suxamethonium 1.0 mg.kg−1 after 60 s [5, 6]. Although there are as yet no published comparisons of morbidity following unanticipated difficult tracheal intubation at RSI with the two agents, I believe that continued unquestioning faith in the ‘safety’ of suxamethonium, based on its (unpredictable) spontaneous offset, is unwarranted.