Optimal bolus dose of alfentanil for successful tracheal intubation during sevoflurane induction with and without nitrous oxide in children

Abstract

The goals of this study were to determine the effective bolus dose of alfentanil required for successful tracheal intubation during inhalation induction using sevoflurane 5% without neuromuscular block in children, and whether nitrous oxide reduces these doses. Fifty paediatric patients, aged 3-10 yr, were randomly assigned to one of the two groups. Subjects received either sevoflurane 5% in oxygen 100% (O(2) group, n=25) or sevoflurane 5% in oxygen 40% and nitrous oxide 60% (N(2)O group, n=25) through a face mask. One minute after inhalation induction, a predetermined dose of alfentanil was injected over 15 s. The alfentanil dose was determined using Dixon's up-and-down method, starting from alfentanil 14 microg kg(-1). The trachea was intubated 3 min after inducing anaesthesia. The ED(50) [95% confidence interval (CI)] of alfentanil for successful tracheal intubation was 11.5 (9.9-13.1) and 8.6 (7.4-9.8) microg kg(-1) in the O(2) and N(2)O groups, respectively. The ED(50) of the N(2)O group was significantly lower than that of the O(2) group (P=0.0146)(.) From isotonic regression, 50% effective dose (ED(50)) (95% CI) of alfentanil in the O(2) and N(2)O groups was 11.4 (9.9-13.0) and 6.5 (5.0-8.1) microg kg(-1), respectively. The effective bolus dose of alfentanil for successful tracheal intubation was 11.5 microg kg(-1) in 50% of children during inhalation induction using sevoflurane 5% without neuromuscular blocking agent. Addition of nitrous oxide 60% in oxygen reduced the effective alfentanil dose by 25%.