Comparison of neostigmine induced reversal of vecuronium in normal weight, overweight and obese female patients

Background and Aims: Obese patients are more vulnerable to residual neuromuscular block (NMB) and its associated complications in the post-operative period. This study was carried out to compare neostigmine induced reversal of vecuronium in normal weight, overweight and obese female patients, objectively using neuromuscular (NM) monitoring. Methods: Twenty female patients each belonging to normal weight, overweight and obese, based on body mass index, requiring general anaesthesia were recruited for this prospective cross sectional study. NMB was induced with vecuronium (0.1 mg/kg) dose based on patient's real body weight (RBW) and monitored using acceleromyographic train of four (TOF). All patients received neostigmine 40 mu g/kg and glycopyrrolate 10 mu g/kg at 25% of spontaneous recovery of first twitch height (T1) of TOF (DUR 25%) and were allowed to recover to TOF ratio of 0.9. Statistical analysis was done using analysis of variance test. Results: Recovery of TOF ratio to 0.5 was comparable in all three groups. Recovery of TOF ratio to 0.7 was delayed in obese (9.82 +/- 3.21 min) compared with normal weight group (7.50 +/- 2.52 min). Recovery of TOF to 0.9 was significantly delayed in both overweight (12.18 +/- 4.29 min) and obese patients (13.78 +/- 4.30 min). DUR 25% was significantly longer in overweight (mean, standard deviation [range]; 30.10 [19-40 min]) and obese (28.8 [12-45 min]) compared with normal weight patients (22.75 [16-30 min]). Conclusion: In overweight and obese patients, when vecuronium induction dose is based on RBW, neostigmine induced recovery of NMB is delayed in late phases (TOF 0.7-0.9), which may result in vulnerability for associated complications of incomplete recovery. Ensuring safe recovery thus requires objective NM monitoring.