Antagonism of atracurium-induced block in obese patients

Abstract

Purpose: To investigate the relationship between total body weight (TBW) or body mass index (BMI) and atracurium reversal time. Methods: The study population comprised 25 patients with TBW <80 kg and 25 patients with TBW ≤80 kg anaesthetised with midazolam, thiopentone, fentanyl, nitrous oxide and halothane, Neuromuscular block was induced with 0.5 mg · kg-1 atracurium and maintained with doses of 0.15 mg · kg-1. Neuromuscular transmission was recorded using train-of-four (TOF) nerve stimulation and mechanomyography. Neostigmine, 0.07 mg · kg-1, was administered when the first twitch in TOF had recovered to 10% of control. Reversal time was defined as: time from administration of neostigmine until TOF ratio recovered to 0.70. Results: There was no difference in reversal time between patients with TBW <80 kg (7.2 ± 2.6 min, mean ± SD), and patients with TBW ≤80 kg (6.9 ± 3.6 min). When patients were grouped according to BMI there was no difference in reversal time between groups 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 patients in the study population with the smallest TBW or BMI and the 15 patients with the greatest TBW or BMI. There was no correlation between TBW or BMI and reversal time. Conclusion: When atracurium-induced neuromuscular block is antagonised with 0.07 mg · kg-1 neostigmine, TBW or BMI have no influence on reversal time.