Effect-site consentration of remifentanil for nasotracheal versus orotracheal intubation during propofol target-controlled infusion

Abstract

Background: The purpose of this study was to determine the effect-site concentrations of remifentanil required for acceptable nasotracheal (NT) intubation in adults after propofol target-controlled infusion (TCI) without neuromuscular blocking agent, and whether or not these concentrations differ from those for orotracheal (OT) intubation.

Methods: Fifty patients were assigned to receive either OT intubation (OT group, n = 25) or NT intubation (NT group, n = 25). Anaesthesia was induced with propofol TCI at the effect-site concentration of 5.0 μg/ml. Two minutes later, the predetermined effect-site concentration of remifentanil was started (from 4.5 ng/ml) using Dixon’s up-and-down method. Tracheal intubation was performed during the remifentanil infusion 2 min after beginning. Acceptable intubation was defined as excellent or good intubating conditions.

Results: EC50 ± SD of remifentanil in the OT and NT groups was 5.58 ± 0.75 ng/ml and 6.08 ± 0.75 ng/ml, respectively; there was no statistical significance between the groups (P = 0.277). Using isotonic regression, EC50 (95% CI) of remifentanil in the OT and NT groups was 5.00 (3.34-7.46) ng/ml and 5.75 (3.66-7.84) ng/mlv, respectively (P = 0.592).

Conclusion: The effect-site concentration of remifentanil for acceptable NT intubation was 6.08 ng/ml in 50% of adults during propofol TCI at an effect-site concentration of 5.0 μg/ml without neuromuscular blocking agent. The predicted effect-site concentration of remifentanil for NT intubation was not different from OT intubation.