[Onset of the effect and intubation conditions following atracurium, verocuronium and suxamethonium].

1. The onset of neuromuscular blockade following i.v. injection of atracurium 0.3, 0.4, or 0.5 mg/kg; vecuronium 0.08 or 0.1 mg/kg; and succinylcholine 1.0 mg/kg was studied in 205 adult patients during induction of anesthesia by means of the compound action potential (EMG) of the hypothenar muscle, which was indirectly stimulated via the ulnar nerve above the wrist, using the Datex Relaxograph. At the same time, the intubation conditions at 0.5, 1, 2, or 3 min after injection were assessed using a scoring system (Crul 1983) related to ease of laryngoscopy, movement of vocal cords and coughing, and reflex movements of the extremities. 2. Neuromuscular blockade and intubation conditions 2 min after administration of atracurium 0.3 mg/kg were 60 +/- 10% and 8.7 +/- 0.3; after 0.4 mg/kg 74 +/- 4% and 10.3 +/- 0.3; and after 0.5 mg/kg 86 +/- 5% and 11.8 +/- 0.2. After 0.08 mg/kg vecuronium 76 +/- 3% and 7.4 +/- 0.5 were recorded and after 0.1 mg/kg 85 +/- 6% and 10.5 +/- 0.4. Motor blockade 1 min after succinylcholine was 98 +/- 2% and intubation conditions scored 11.3 +/- 0.3. Relating intubation conditions to neuromuscular blockade yielded a close correlation and surprisingly good or very good intubation conditions (score more than 10) at a motor blockade of 80% (resp. 20% transmission). 3. Although succinylcholine is still the muscle relaxant with the most rapid onset of action, the new drug atracurium seems to satisfactorily facilitate tracheal intubation within an acceptably short time interval of 2 min after injection.(ABSTRACT TRUNCATED AT 250 WORDS)