ANTAGONISM OF ATRACURIUM-INDUCED BLOCK IN OBESE PATIENTS

Purpose: To investigate the relationship between total body weight (TB W) or body mass index (BMI) and atracurium reversal time. Methods: The study population comprised 25 patients with TBW <80 kg and 25 patient s with TBW greater than or equal to 80 kg anaesthetised with midazolam , thiopentone, fentanyl, nitrous oxide and halothane. Neuromuscular bl ock was induced with 0.5 mg . kg(-1) atracurium and maintained with do ses of 0.15 mg . kg(-1). Neuromuscular transmission was recorded using train-of-four (TOF) nerve stimulation and mechanomyography, Neostigmi ne, 0.07 mg . kg(-1), was administered when the first twitch in TOF ha d recovered to 10% of control. Reversal time was defined as: time from administration of neostigmine until TOF ratio recovered to 0.70. Resu lts: There was no difference in reversal time between patients with TB W <80 kg (7.2 +/- 2.6 min, mean +/- SD), and patients with TBW greater than or equal to 80 kg (6.9 +/- 3.6 min). When patients were grouped according to BMI there was no difference in reversal time between grou ps with low BMI (6.9 +/- 2.6 min) or high BMI (7.1 +/- 3.6 min), There was, furthermore, no difference in reversal time between the 15 patie nts in the study population with the smallest TBW or BMI and the 15 pa tients with the greatest TBW or BMI, there was no correlation between TBW or BMI and reversal time, Conclusion: When atracurium-induced neur omuscular block is antagonised with 0.07 mg . kg(-1) neostigmine, TBW or BMI have no influence on reversal time.