[Vecuronium: onset of effect and intubation conditions in comparison to pancuronium and suxamethonium]

The onset of neuromuscular blockade following the i.v. injection of vecuronium and pancuronium 0.05, 0.08 or 0.1 mg/kg and suxamethonium 0.5 or 1.0 mg/kg was studied in 304 patients during induction of anaesthesia by means of the compound action potential derived from the adductor pollicis muscle, which was indirectly stimulated via the ulnar nerve. The intubation conditions 1-5 min after injection were assessed using a scoring system related to ease of laryngoscopy, movement of vocal cords and coughing, and reflex movements of extremities. Development of motor blockade was time- and dose-dependent. After administration of 0.1 mg/kg vecuronium, the actual maximum effect (more than 90% block) was established within 4 min; after 0.1 mg/kg pancuronium within 6 min and after 1.0 mg/kg suxamethonium within 2 min. Intubation conditions improved with time. After 0.1 mg/kg vecuronium atraumatic intubation was possible within 2 min and after 0.1 mg/kg pancuronium within 4 min. Following 1.0 mg/kg suxamethonium, optimum intubation conditions were achieved within 1 min. Although suxamethonium acts the fastest and tracheal intubation can be achieved within 0.5-1.0 min, its use involves certain side effects and disadvantages. Vecuronium acts considerably faster than pancuronium and good or excellent intubation conditions are present within 2 min. Suxamethonium is no longer the muscle relaxant of choice for intubation except for crash intubation, e.g., in patients with a full stomach.