Incidence of postoperative residual neuromuscular blockade in the postanaesthesia care unit

Abstract

Residual neuromuscular blockade still presents despite the use of intermediate duration muscle relaxants and is a risk factor for postoperative morbidity. To determine the incidence of incomplete postoperative neuromuscular recovery from anaesthesia in a postanaesthesia care unit. Multicentre observational study. Public Portuguese hospitals. Adult patients scheduled for elective surgery requiring general anaesthesia with neuromuscular blocking agents. An independent anaesthesiologist measured neuromuscular transmission by the TOF-Watch SX acceleromyograph. Train-of-four ratios at least 0.9 and less than 0.9 were assessed as complete and incomplete neuromuscular recovery following general anaesthesia, respectively. The study population consisted of 350 patients [134 men and 216 women, mean (SD) age 54.3 (15.9) years]. Ninety-one patients had a train-of-four ratio less than 0.9 on arrival in the postanaesthesia care unit, an incidence of residual neuromuscular blockade of 26% [95% confidence interval (CI) 21 to 31%]. The most frequent neuromuscular blockers were rocuronium (44.2%) and cisatracurium (32%). A neuromuscular block reversal agent was used in 66.6% of the patients (neostigmine in 97%). The incidence of residual neuromuscular blockade in patients receiving reversal agents was 30% (95% CI 25 to 37%). There were no statistically significant differences in the occurrence of residual blockade relating to the neuromuscular blocker used, although higher percentages were observed for cisatracurium (32.4%) and vecuronium (32%) compared with atracurium (23.6%) and rocuronium (20.8%). Incomplete neuromuscular recovery was significantly more frequent among patients who had received a reversal agent (30.5 vs. 17.1%, P = 0.01). Incomplete neuromuscular recovery was more frequent in patients given propofol than in those exposed to sevoflurane (26.2 vs. 14.3%). The incidence of incomplete neuromuscular recovery of 26% confirms that it is relatively frequent in the postoperative period and calls attention to the dimension of this problem in Portugal.