The effect of circadian rhythm on vecuronium induced neuromuscular block

Summary: objective: this study aimed to analyze the effect of the circadian rhythm on the neuromuscular block duration induced by a standard dose of vecuronium bromide. methods: after ethical committee approval,we enrolled 104 asa class i-ii patients who were to have a surgical operation with an expected duration not less than 60 minutes into the study. anesthesia induction was provided with 2-2.5 mg kg-1 propofol,0.1 mg kg-1 vecuronium bromide,and the maintenance of anesthesia with sevoflurane + 50% n2o + 50% o2 in 1-2% concentration. according to the application time of the vecuronium,the patients were divided into four groups: group i (n=26) who had anesthesia in the forenoon (06:00-12:00 a.m.) (in the morning),group ii (n=26) who had anesthesia in the afternoon (12:00-18:00 p.m.) (in the afternoon),group iii (n=26) who had anesthesia in the evening (18:00-24:00) and group iv (n=26) who had anesthesia at night (24:00-06:00). the neuromuscular block time was measured using 'single twitch' (st) mode of tof- watch apparatus. results: a total of 104 patients,50 women and 54 men,aged between 18-65 years who had elective and/or emergency surgery were evaluated statistically in this study. one patient in the morning group and three patients in the evening group were excluded (four patients in total) because surgery ended before reaching st 25%. a significant difference was not observed among four groups in terms of st first lag time,st maximum lag time,first response time to st,st 10% and 25% recovery times related to the neuromuscular conduction. conclusion: we concluded that the standard induction dose of vecuronium bromide applied in the different hours of the day did not affect the neuromuscular block duration.