Background: The purpose of this study was to compare neostigmine-induced reversal of vecuronium in normal weight, overweight and obese female patients.
Methods: In total, 15 each of normal weight (18.5<or=BMI<25), overweight (25<or=BMI<30) and obese (BMI>or=30) patients were enrolled. Anaesthesia was induced and maintained with fentanyl, propofol and nitrous oxide. Neuromuscular block was induced with vecuronium 0.1 mg kg(-1) on the basis of the patient's real body weight (RBW) and was monitored using acceleromyographic train-of-four (TOF) of the adductor pollicis. All patients received neostigmine 0.04 mg kg(-1) combined with atropine 0.02 mg kg(-1) at 25% recovery of the first twitch (T1) of TOF and were allowed to recover to a TOF ratio of 0.9.
Results: The time from administration of vecuronium to spontaneous recovery of T1 to 25% of control was significantly longer in the obese [mean (SD, range); 68.4 (16.3, 39.8-110.8) min] and the overweight groups [49.3 (6.2, 39.8-60.8) min] as compared with the normal weight group [41.0 (9.0, 27.5-59.5) min]. The times for facilitated recovery with neostigmine to a TOF ratio of 0.7 did not differ among groups. However, the recovery to a TOF ratio of 0.9 in the obese [25.9 (6.7, 13.5-41.0) min] and the overweight groups [14.6 (7.7, 3.3-28.5) min] were significantly longer than that in the normal weight group [6.9 (2.0, 3.0-10.7) min].
Conclusions: Early reversal after neostigmine is prompt; however, recovery to a TOF ratio of 0.9 is slow in overweight and obese patients when vecuronium is dosed on the basis of the patient's RBW.