Journal of the Indian Medical Association
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Randomized Controlled Trial Clinical Trial
A pharmacodynamic basis for the peak effect of vecuronium: peak twitch versus peak tetanic fade.
Double burst stimulation (DBS), a tetanic test, shows two types of changes during nondepolarising neuromuscular block (NMB) viz, amplitude (D1) suppression and fading of second response (D2), quantified as DBS ratio (D2/D1). During subclinical dose effect of vecuronium bromide both parameters show peak suppression at two distinct intervals. To evaluate, which of the two is the true peak effect of vecuronium, twenty-two ASA 1 patients were given im buprenorphine (5 micro/kg) premedication and iv diazepam (0.1 mg/kg). ⋯ It was noteworthy that at the repeat dose of vecuronium while D1 showed recovery in group 2 patients, DBS ratio was concomitantly and significantly lower (0.37 +/- 0.10) (more intense NMB) than in group 1 (0.49 +/- 0.17) patients, with quicker onset of repeat dose. These findings suggest that as the NMB agents show two types of changes during clinical monitoring, DBS test seems to be a better clinical pharmacodynamics-monitoring test for NMB agents. In addition, the peak tetanic fade (peak DBS ratio suppression) correlated with peak effect of vecuronium than the usually measured peak twitch suppression.