Dose-response relationship and effective time to satisfactory intubation conditions after rocuronium in children.

Abstract

We assessed the neuromuscular blocking effects of, and intubation conditions following, rocuronium in 81 children aged 2-12 years. The study was conducted in three parts. Parts 1 and 2 were undertaken during anaesthesia with thiopentone, alfentanil and nitrous oxide. Neuromuscular blockade was evaluated by recording the force of contraction of the adductor pollicis in response to train-of-four stimulation at 2 Hz repeated every 10s. In Part 1 the potency of rocuronium was determined in 15 children using a single dose-response technique; in Part 2 onset and recovery times were determined in six children following rocuronium 0.6 mg.kg-1. In Part 3 of the study, intubation conditions were assessed in five groups of 12 children whose tracheas were intubated 30, 40, 50, 60 and 70s after rocuronium 0.6 mg.kg-1 during anaesthesia with thiopentone. The times to satisfactory intubation conditions in 50% and 90% of children were determined by probit analysis. The effective doses of rocuronium to produce 50% and 95% twitch depression were 151 micrograms.kg-1 (95% confidence intervals: 129-173 micrograms.kg-1) and 331 micrograms.kg-1 (95% confidence intervals: 249-543 micrograms.kg-1), respectively. The mean times (SD) to 90% and 100% depression of control twitch following rocuronium 0.6 mg.kg-1 were 42 (11.8) s and 60.3 (19.3) s, respectively. The times to 5%, 25%, 75% and 90% recovery were 20.5 (3.1) min, 26.1 (4.1) min, 35.1 (5.4) min, and 39.5 (6.4) min, respectively. Intubation conditions were satisfactory in 4/12 children at 30 s, 6/12 at 40 s, 8/12 at 50 s, 11/12 at 60 s and 12/12 at 70 s. The times to satisfactory intubation conditions in 50% and 90% of children after rocuronium 0.6 mg.kg-1 were 38 s (95% confidence intervals: 30-44 s) and 61 s (95% confidence intervals: 55-70 s), respectively.