BACKGROUND: During induction of general anesthesia, it is common practice to delay neuromuscular blockade until the ability to deliver mask ventilation has been confirmed. However, the benefits of this approach have never been scientifically validated. We thus compared the early and late administration of rocuronium before and after checking mask ventilation to investigate the efficiency of mask ventilation and the time to tracheal intubation in patients with normal airways.
METHODS: Patients (n = 114) were randomized to receive IV rocuronium either before (early rocuronium group, n = 58) or after (late rocuronium group, n = 56) checking mask ventilation. Expiratory tidal volumes (VTs) were measured at 10, 20, 30, 40, 50, and 60 seconds after apnea during mask ventilation. We graded the ease of mask ventilation and measured the time from apnea to tracheal intubation. The primary outcome was the average of mask VTs measured at 10, 20, 30, 40, 50, and 60 seconds after apnea. The main secondary outcome was the time from apnea to tracheal intubation. STATA was used for statistical analysis.
RESULTS: The average of mask VTs measured at 10, 20, 30, 40, 50, and 60 seconds after apnea was larger in the early rocuronium group than in the late rocuronium group (552 mL breath−1 [165 mL breath−1] vs 393 mL breath−1 [165 mL breath−1], mean difference, 160 mL breath−1; 95% CI, 98−221 mL breath−1; P < .001, unpaired t test). Because the interaction between time and group was significant in mask VTs measured at 10, 20, 30, 40, 50, and 60 seconds after apnea (P < .001, linear mixed effects model), pairwise comparisons were performed at the 6 time points. The differences in VTs between the groups were significant at 10, 20, 30, 40, and 50 seconds after apnea (P < .001 each, contrast statements in STATA). The time from apnea to tracheal intubation was shorter in the early rocuronium group than in the late rocuronium group (116 seconds [42 seconds] vs 195 seconds [41 seconds]; mean difference, −79 seconds; 95% CI, −96 to −64 seconds, P < .001).
CONCLUSIONS: The early administration of rocuronium before checking mask ventilation resulted in a larger mask VT and earlier tracheal intubation than the late administration of rocuronium after checking mask ventilation in patients with normal airways.