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

Abstract

BACKGROUND: 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.

METHODS: 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.

RESULTS: 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.

CONCLUSIONS: 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%.