Determining the optimal time for endotracheal intubation during onset of neuromuscular blockade

The disappearance of the response to single twitch stimulation (STS), double burst stimulation (DBS) and zero post-tetanic count (PTC) were evaluated to determine which best indicated the optimal time of endotracheal intubation during onset of neuromuscular blockade induced by vecuronium (0.08 mg kg-1) in 199 patients under thiopentone and halothane anaesthesia. Evaluations were performed by mechanomyographic and manual methods using a Myograph and a peripheral nerve stimulator. The study consisted of six parts. In part 1 (n = 30) and part 2 (n = 30), the response to STS (0.1 Hz) were evaluated mechanically and manually, respectively. In part 3 (n = 64), post-tetanic count (PTC) changes were evaluated mechanically. In part 4 (n = 30) and part 5 (n = 30), response to DBS were evaluated mechanically and manually, respectively. Intubation was performed immediately after obtaining zero PTC, or absence of response to STS (0.1 Hz) and DBS, and the intubation score was determined. In the control group of patients, intubation was performed under the same anaesthetic conditions as in parts 1-5 but without the administration of any muscle relaxant. The time from administration of any muscle relaxant. The time from administration of vecuronium until disappearance of response was 2.16 +/- 0.56, 2.49 +/- 0.68, 2.04 +/- 0.29, 2.20 +/- 0.53, and 2.97 +/- 0.61 min in parts 1-5, respectively. Excellent intubation conditions were not established in any of the control patients, and in 50.0, 70.0, 55.0, 70.0 and 90.0% of the patients in parts 1-5, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)