Effect-site concentration of remifentanil for preventing cough during emergence in elderly patients undergoing nasal surgery: a comparison with adult patients

PURPOSE Prevention of cough during emergence after nasal surgery is important for avoiding surgical site bleeding. We investigated the remifentanil effect-site concentration in 50% (EC50) of the elderly patients undergoing nasal surgery for smooth emergence without cough and compared it with that of adult patients. METHODS Twenty-two elderly (aged 65-80 years) and 25 adult patients (aged 20-60 years) with an American Society of Anesthesiologists physical status I/II undergoing nasal surgery were enrolled. Anesthesia was maintained with sevoflurane and remifentanil. Remifentanil EC50 and EC95 for preventing cough were determined using the modified Dixon's up-and-down method and isotonic regression with bootstrapping approach. Recovery profiles were also recorded. RESULTS With Dixon's up-and-down method, the EC50 of remifentanil in elderly patients (2.40±0.25 ng/mL) was not significantly different from that of adults (2.33±0.30 ng/mL) (P=0.687). With isotonic regression, the EC95 of remifentanil in elderly patients (3.32 [95% confidence interval: 3.06-3.38] ng/mL) was not significantly different from that of adults (3.30 [95% confidence interval: 2.96-3.37] ng/mL). However, eye opening time (14.1±3.8 vs 12.0±2.9 seconds), extubation time (17.2±4.1 vs 14.0±3.0 seconds), and postanesthesia care unit duration (44.5±7.6 vs 38.7±3.4 minutes) in elderly patients were significantly longer than those in adults (P<0.05). CONCLUSION Remifentanil EC50 for preventing cough after nasal surgery with sevoflurane anesthesia did not differ between elderly and adult patients. However, delayed awakening and respiratory adverse events may warrant attention in elderly patients.