Neostigmine Administration after Spontaneous Recovery to a Train-of-Four Ratio of 0.9 to 1.0: A Randomized Controlled Trial of the Effect on Neuromuscular and Clinical Recovery

Background: When a muscle relaxant is administered to facilitate intubation, the benefits of anticholinesterase reversal must be balanced with potential risks. The aim of this double-blinded, randomized noninferiority trial was to evaluate the effect of neostigmine administration on neuromuscular function when given to patients after spontaneous recovery to a train-of-four ratio of 0.9 or greater. Methods: A total of 120 patients presenting for surgery requiring intubation were given a small dose of rocuronium. At the conclusion of surgery, 90 patients achieving a train-of-four ratio of 0.9 or greater were randomized to receive either neostigmine 40 μg/kg or saline (control). Train-of-four ratios were measured from the time of reversal until postanesthesia care unit admission. Patients were monitored for postextubation adverse respiratory events and assessed for muscle strength. Results: Ninety patients achieved a train-of-four ratio of 0.9 or greater at the time of reversal. Mean train-of-four ratios in the control and neostigmine groups before reversal (1.02 vs. 1.03), 5 min postreversal (1.05 vs. 1.07), and at postanesthesia care unit admission (1.06 vs. 1.08) did not differ. The mean difference and corresponding 95% CI of the latter were -0.018 and -0.046 to 0.010. The incidences of postoperative hypoxemic events and episodes of airway obstruction were similar for the groups. The number of patients with postoperative signs and symptoms of muscle weakness did not differ between groups (except for double vision: 13 in the control group and 2 in the neostigmine group; P = 0.001). Conclusions: Administration of neostigmine at neuromuscular recovery was not associated with clinical evidence of anticholinesterase-induced muscle weakness. Visual Abstract: An online visual overview is available for this article.