Smooth emergence in men undergoing nasal surgery: the effect site concentration of remifentanil for preventing cough after sevoflurane‐balanced anaesthesia

Abstract

Suppression of cough during emergence after nasal surgery is practical to avoid bleeding from the surgical site. Previously recommended effect-site concentration of remifentanil for preventing cough during emergence is restricted to female patients undergoing thyroid surgery, so we evaluated effective effect-site concentration of remifentanil for preventing cough during emergence for men undergoing nasal surgery. Twenty-four American Society of Anesthesiologists (ASA) physical status I or II, between the ages of 18 and 60 years old, non-smoker male patients undergoing nasal surgery were enrolled in this study. The effective effect-site concentration for 50% of patients (EC(50) ) and and that for 95% of patients (EC(95) ) of remifentanil for preventing cough were determined by Dixon's up-and-down method and by isotonic regression method with a bootstrapping approach. Haemodynamic variables were compared in patients with cough and without cough during emergence. The EC(50) of remifentanil for preventing cough during emergence by Dixon's method was 2.17 ng/ml [standard deviation (SD) 0.38]. The estimated EC(50) and EC(95) of remifentanil using isotonic regression model with a bootstrapping approach were 2.35 ng/ml [95% confidence interval (CI) 1.89-2.66] and 2.94 ng/ml (95% CI 2.83-2.97), respectively. Mean arterial pressure and heart rate were significantly higher in patients with cough during emergence. Three out of 13 patients that received more than 2.5 ng/ml of remifentanil experienced a brief episode of bradypnea. The EC(95) of remifentanil for preventing cough in men after nasal surgery is 2.94 ng/ml. Remifentanil target-controlled infusion with established effect-site concentration could suppress cough in men during emergence from sevoflurane anaesthesia after nasal surgery, though reversible respiratory depression might arise at high effect-site concentration of remifentanil.