A comparison of intubation conditions and time-course of action with rocuronium and mivacurium for day case anaesthesia

BACKGROUND AND OBJECTIVE: To compare intubation conditions and time-course of action of rocuronium and mivacurium for day case anaesthesia. METHODS: Fifty ASA I or II patients were enrolled. Anaesthesia was induced with propofol using a target controlled infusion system (target 6-8 microg mL(-1) ) and sufentanil (0.25 microg mL(-1). It was maintained with propofol (target 3.5-4.5 microg mL(-1) and 50% nitrous oxide in oxygen. Muscle relaxation was achieved with either mivacurium (0.15 mg kg(-1)) or rocuronium (0.3 mg kg(-1)). Neuromuscular transmission was monitored and recorded continuously by acceleromyography using a TOF-WATCH SX (Biometer; Denmark) with supramaximal train-of-four stimulation of the ulnar nerve. Tracheal intubation was carried out by an experienced anaesthetist blinded to the type of the muscle relaxant. Intubation conditions were evaluated according to a standard scheme (ease of laryngoscopy, position of vocal cords, airway reaction and limb movements). RESULTS: Intubation conditions were good or excellent for both mivacurium 0.15 mg kg(-1) (good = 8%; excellent = 92%) and rocuronium 0.3 mg kg(-1) (excellent = 100%). Times to maximum blockade and clinical duration were not different. CONCLUSIONS: There is no significant difference between mivacurium and rocuronium concerning the onset and the recovery of muscle relaxation. Rocuronium is an alternative to mivacurium for short procedures, without the risk of unexpected prolonged relaxation due to a possible defect in plasma cholinesterase.