Optimal rocuronium dose for intubation during inhalation induction with sevoflurane in children

Background. We studied 120 children aged 2-7 yr in a prospective, randomized, assessor-blinded fashion to define the optimal rocuronium dose which provides a 95% probability of acceptable intubation conditions (ED_95TI) during inhalation induction with sevoflurane. Methods. After inhalation induction with 8% sevoflurane in 60% nitrous oxide and 40% oxygen, and loss of the eyelash reflex, we administered rocuronium (0.1, 0.15, 0.22, 0.3, or 0.6 mg kg^-1) or placebo. We quantified neuromuscular function by stimulation of the ulnar nerve at 0.1 Hz to produce contraction of the adductor pollicis muscle using accelerometry. Intubation conditions were assessed 2 min after test drug injection. The optimal rocuronium dose was defined as the lowest dose, which allowed acceptable intubation conditions in 95% of children (ED_95TI). Results. Two minutes after injection of placebo or rocuronium, intubation conditions were acceptable in 35, 45, 80, 90, 95, and 100% of children, respectively. Rocuronium 0.07 [CI 0.02-0.11], 0.24 [0.19-0.31], and 0.29 [0.23-0.38] mg kg^-1 provided 50, 90, and 95% probability of acceptable intubating conditions. When thumb acceleration was depressed by 50% or more, intubating conditions were considered acceptable in 97% of children. Recovery of the train-of-tour ratio to 0.8 averaged 12 (7), 16 (7), 24 (7), 24 (8), and 50 (22) min after the respective dose of rocuronium. Conclusions. During inhalation induction with 8% sevoflurane in 60% nitrous oxide, rocuronium 0.29 mg kg^-1 (ED₉₅) optimizes intubation conditions for surgery of short duration.