Effect of a Bolus Dose of Fentanyl on the ED50 and ED95 of Sevoflurane in Neonates

BACKGROUND The minimum alveolar concentration (MAC) of sevoflurane in neonates is 3.3%, but this value has not been verified in Chinese neonates and the effect of different doses of fentanyl on MAC in neonates has not been investigated. This study was designed to determine the ED₅₀ and ED₉₅ values of sevoflurane in Chinese neonates with and without fentanyl. MATERIAL AND METHODS Ninety-three neonates were randomly assigned to receive sevoflurane alone (control group, n=30), 1 µg/kg sevoflurane (group fent1, n=29), or 2 µg/kg fentanyl (group fent2, n=32). Following inhalational induction and tracheal intubation, the end-tidal concentration of sevoflurane was adjusted to achieve the designated concentration, which was determined using the modified Dixon's up-and-down method starting with 3.0% in each group, with a 0.25% step size. Success was defined as no motor response within 60 s of skin incision. RESULTS The MAC (standard deviation) values of sevoflurane were 2.91% (0.27) in the control group, 2.53% (0.31) in the fent1 group, and 2.34% (0.33) in the fent2 group according to Dixon's up-and-down method. Logistic probit regression analysis revealed that the ED₅₀ and ED₉₅ (95% CI) of sevoflurane in neonates were 2.82% (2.66-2.98) and 3.39% (2.89-3.89), respectively, in the control group; 2.44% (2.19-2.68) and 3.30% (2.51-4.09), respectively, in the fent1 group; and 2.21% (1.97-2.45) and 3.11% (2.35-3.88), respectively, in the fent2 group. CONCLUSIONS The MAC value of sevoflurane in Chinese neonates was lower than previously reported and was reduced by the addition of fentanyl.