Rapacuronium 2.0 or 2.5 mg kg(-1) for rapid-sequence induction: comparisonwith succinylcholine 1.0 mg kg(-1)

The purpose of this nine-centre study in 602 patients was to show that the frequency of acceptable intubating conditions after rapacuronium 2.0 or 2.5 mg kg(-1) is not more than 10% lower than the frequency after succinylchol ine 1.0 mg kg(-1) during rapid-sequence induction of anaesthesia with fenta nyl 1-2 mug kg(-1) and thiopental 2-7 mg kg(-1). Laryngoscopy and intubatio n were carried out 60 s after administration of muscle relaxant by an anaes thetist blinded to its identity. Intubating conditions were clinically acce ptable (excellent or good) in 91.8% of patients given succinylcholine and i n 84.1 and 87.6% of patients given rapacuronium 2.0 and 2.5 mg kg(-1) respe ctively. With respect to the percentage of clinically acceptable intubating conditions, the estimated difference (and the upper limit of the one-sided 97.5% confidence interval) between succinylcholine and rapacuronium 2.0 mg kg(-1) was 7.8 (14.4)% and between succinylcholine and rapacuronium 2.5 mg kg(-1) it was 4.0 (10.2)%. For both comparisons, the upper limit of the on e-sided confidence interval exceeded the predefined 10% difference. Hence, it could not be demonstrated that the intubating conditions with either of the two doses of rapacuronium were not inferior to those with succinylcholi ne 1.0 mg kg(-1). The increase in heart rate was significantly greater duri ng the first 5 min in the rapacuronium groups, but the arterial pressure in creased significantly only in the succinylcholine group (P<0.001). Respirat ory side-effects were observed in 4.0, 13.5 and 18.5% of patients after suc cinylcholine and rapacuronium 2.0 and 2.5 mg kg(-1) respectively (P<0.05). As the non-inferiority of intubating conditions after rapacuronium 2.0 and 2.5 mg kg(-1) could not be proven, succinylcholine should be considered the neuromuscular blocking agent that provides better intubating conditions fo r rapid-sequence induction.