Summary This randomised, double‐blinded, controlled trial was designed to identify the optimal dose of remifentanil for cough suppression without adverse effects during emergence from sevoflurane‐remifentanil anaesthesia for thyroidectomy. One hundred and four patients were randomly assigned to maintain target effect‐site concentrations of remifentanil at 0 (control group), 1.0 (remifentail 1 group), or 1.5 ng.ml−1 (remifentanil 1.5 group) during emergence. The incidence of coughing was lower in the remifentanil 1.5 group (31%) than in the control group (74%) or remifentanil 1 group (63%) (p = 0.0004). In addition, the severity of coughing during extubation was lower in the remifentanil 1.5 group (median (IQR [range]) 0 (0–1 [0–1]) than in the control group (1 (0–2 [0–3])) and remifentanil 1 group (1 (0–2 [0–3])) (p = 0.004). Haemodynamic changes were reduced, but emergence time and stay in the post‐anaesthesia care unit was prolonged in the remifentanil 1.5 group. Maintaining the remifentanil effect‐site concentration at 1.5 ng.ml−1 during emergence from sevoflurane‐remifentanil anaesthesia reduces the incidence and severity of coughing without serious adverse events and may provide haemodynamic stability in patients undergoing thyroidectomy. However, awakening may be delayed.

SummaryThe purpose of this study was to determine the effect-site concentration of remifentanil that would provide optimal conditions for successful laryngeal mask airway insertion during a target-controlled infusion (TCI) of propofol at 3.5 lg.ml )1 without the use of neuromuscular blockade. Five minutes after propofol infusion, remifentanil was infused at a dose determined by a modified Dixon's up-and-down method. Five minutes after remifentanil infusion, the laryngeal mask was inserted.The effect-site concentration of remifentanil for successful laryngeal mask insertion in 50% of adults (EC 50 ) was 3.04 (SD 0.49) ng.ml )1 during a TCI of 3.5 lg.ml )1 propofol without neuromuscular blockade. From the probit analysis, the EC 50 and EC 95 of remifentanil were 2.84 ng.ml )1 (95% CI 2.09-3.57 ng.ml) and 3.79 ng.ml )1 (95% CI 3.26-9.25 ng.ml )1 ), respectively.