Effects of different doses of remifentanil on the end-tidal concentration of sevoflurane required for tracheal intubation in children.

Abstract

We investigated the effects of different doses of remifentanil on the end-tidal concentration of sevoflurane required for tracheal intubation in children without the use of neuromuscular blocking drugs. One hundred and thirty paediatric patients, aged 3-8 years, were randomly allocated to receive no remifentanil (group control) or remifentanil 0.1 microg kg(-1) min(-1) (group remi(0.1)), 0.2 microg kg(-1) min(-1) (group remi(0.2)), 0.3 microg kg(-1) min(-1) (group remi(0.3)). All patients were anaesthetised using 5% sevoflurane. After loss of eyelash reflex, remifentanil 1 microg kg(-1) was injected over 1 min followed by an appropriate group-dependent infusion and the end-tidal sevoflurane concentration was changed. Predetermined end-tidal sevoflurane concentrations for each group were determined using the Dixon up-and-down method. After the target concentration of sevoflurane was maintained for 5 min, the child's trachea was intubated. Successful intubation was defined as excellent or good intubating conditions. The end-tidal concentration (SD) of sevoflurane for successful tracheal intubation in 50% of children (ED(50)) were 5.16 (0.22)% in control, 3.27 (0.18)%, 1.81 (0.20)% and 1.01 (0.11)%, in remi(0.1), remi(0.2), and remi(0.3) groups, respectively. Using probit analysis, the 95% effective dose (ED(95)) of sevoflurane were 5.60% (95% CI 5.35-7.66), 3.77% (95% CI 3.45-7.74), 2.18% (95% CI 1.96-3.86), 1.19% (95% CI 1.06-1.82) in control, remi(0.1), remi(0.2), and remi(0.3) groups, respectively.