Rocuronium Dosing by Ideal vs Total Body Weight in Obesity: A Prospective, Observational Non-inferiority Study.

Background: Providing adequate paralysis and appropriate sedation is challenging in patients with obesity during rapid sequence intubation (RSI). Pharmacokinetic parameters play an important role in dosing of rocuronium due to low lipophilicity. Rocuronium may be dosed based on ideal body weight (IBW). Current guidelines do not offer recommendations for dosing in the setting of obesity. Dosing depends on clinician preference based on total body weight (TBW) or IBW.

Objective: In this study we performed non-inferiority analysis to compare the intubation conditions, duration of paralysis, and incidence of new-onset tachycardia or hypertension after intubation in obese patients requiring RSI in the emergency department (ED).

Methods: This was a single-center, prospective, observational study. Eligible for enrollment were adult patients with a TBW ≥30% IBW or body mass index ≥30 kilograms per meters squared who presented to the ED requiring RSI with the use of rocuronium. Rocuronium was dosed according to intubating physicians' preference. Physicians completed a survey assessing intubation conditions. Height and weight used for the calculation of the dose, the dose of rocuronium, time of administration, and time of muscle function recovery were recorded. Endpoints assessed included grading of view during laryngoscopy, first-past success, and duration of paralysis.

Results: In total, 96 patients were included, 54 in TBW and 42 in IBW. The TBW cohort received a mean of 1 milligram per kilogram (mg/kg) compared to 0.71 mg/kg in the IBW group. Excellent intubation conditions were observed in 68.5% in the TBW group and 73.8% in the IBW group. The non-inferiority analysis for relative risk of excellent intubation was 1.12 (P = 0.12, [90% CI 0.80-1.50]).

Conclusion: Non-inferiority analysis suggests that IBW dosing provides similar optimal intubation conditions when compared to TBW dosing, but the noninferiority comparison did not reach statistical significance. This study was unable to show statistical non-inferiority for IBW dosing.