[Intubation requirements after rocuronium and succinylcholine]

Rocuronium is a new non-depolarising steroidal muscle relaxant with a short onset time. The present study was undertaken to compare intubating conditions as well as onset and clinical duration of a single dose of 0.6 mg/kg (2 x ED95) with a single dose of 1 mg/kg suxamethonium (3 x ED95).

After obtaining informed consent and approval of the Ethics Committee, 40 adult patients (ASA I-III) participated in this study. After premedication with oxazepam, anaesthesia was induced with fentanyl and propofol and maintained with propofol, N2O and supplements of fentanyl as needed. Muscular relaxation was assessed by EMG recording of adductor pollicis muscle after supramaximal single twitch stimulation of the ulnar nerve every 10 s. Patients were allocated randomly to receive either rocuronium 0.6 mg/kg or suxamethonium 1 mg/kg. The following parameters were measured: intubating conditions 60 s after injection, onset time and clinical duration of neuromuscular block, % block at intubation, heart rate, blood pressure and arterial oxygen saturation.

(mean +/- SD). Intubating conditions after rocuronium and suxamethonium were found to be clinically acceptable (excellent or good) in 90% of patients, though there was only a partial blockade of the adductor pollicis muscle with rocuronium (71 +/- 23%) compared to suxamethonium (95 +/- 14%) (p < 0.05). The onset time and clinical duration of relaxation was shorter after suxamethonium (p < 0.05) and occurred at 0.8 +/- 0.2, 7 +/- 2.1 and 3.2 +/- 1.3, 29 +/- 11 min after suxamethonium and rocuronium respectively.

At a dosage of 0.6 mg/kg, rocuronium has an onset time of about 3 min and a clinical duration of relaxation of nearly half an hour. These data are supported by various studies, while others show shorter times, probably due to different monitoring techniques. In spite of the pharmacodynamic differences between suxamethonium and rocuronium, the intubating conditions after administration of both compounds are comparable and develop at the same rate.