Comparison of the effect of rocuronium dosing based on corrected or lean body weight on rapid sequence induction and neuromuscular blockade duration in obese female patients.

Objectives: To compare onset time, duration of action, and tracheal intubation conditions in obese patients when the intubation dose of rocuronium was based on corrected body weight (CBW) versus lean body weight (LBW) for rapid sequence induction. 

Methods: This prospective study was carried out at Numune Education and Research Hospital, Ankara, Turkey between August 2013 and May 2014. Forty female obese patients scheduled for laparoscopic surgery under general anesthesia were randomized into 2 groups. Group CBW (n=20) received 1.2 mg/kg rocuronium based on CBW, and group LBW (n=20) received 1.2 mg/kg rocuronium based on LBW. Endotracheal intubation was performed 60 seconds after injection of muscle relaxant, and intubating conditions were evaluated. Neuromuscular transmission was monitored using acceleromyography of the adductor pollicis. Onset time, defined as time to depression of the twitch tension to 95% of its control value, and duration of action, defined as time to achieve one response to train-of-four stimulation (T1) were recorded.

Results: No significant differences were observed between the groups in intubation conditions or onset time (50-60 seconds median, 30-30 interquartile range [IQR]). Duration of action was significantly longer in the CBW group (60 minutes median, 12 IQR) than the LBW group (35 minutes median, 16 IQR; p less than 0.01).

Conclusion: In obese patients, dosing of 1.2 mg/kg rocuronium based on LBW provides excellent or good tracheal intubating conditions within 60 seconds after administration and does not lead to prolonged duration of action.