Background and Goal of Study: Prevention of cough during emergence after nasal surgery is important to avoid bleeding from the surgical site. We designed this study to investigate remifentanil effect-site concentration in 50% of patients (EC50) for smooth emergence without cough in elderly patients, and to compare it with that in adult patients undergoing nasal surgery.
Materials and methods: Twenty-two elderly patients (65-80 yrs) and 25 adult patients (20-60 yrs) with ASA physical status I or II undergoing nasal surgery were enrolled in this study. Anaesthesia was maintained with sevoflurane and remifentanil. EC50 and EC95 of remifentanil for preventing cough were determined using modified Dixon´s up-and-down method and isotonic regression method with bootstrapping approach. In addition, recovery profiles were recorded.
Results and discussion: Using the Dixon's up and down method, EC50 of remifentanil in elderly group (2.40 ± 0.0.25 ng/ml) were not significantly different in the adult group (2.33 ± 0.30 ng/ml) (p=0.687). Using isotonic regression, EC95 (95% CI) of remifentanil in elderly group [3.32 (3.06-3.38) ng/ml] were not significantly different in the adult group [3.30 (2.96-3.37) ng/ml]. However, eye opening time (14.1 ± 3.8 s vs. 12.0 ± 2.9 s), extubation time (17.2 ± 4.1 s vs. 14.0 ± 3.0 s), and PACU stay (44.5 ± 7.6 min vs. 38.7 ± 3.4 min) in the elderly group was significantly longer than in the adult group. (all ps< 0.05). 
Conclusion(s): In the elderly patients, effect-site concentration of remifentanil for preventing cough after nasal surgery from sevoflurane anaesthesia did not differ in the adult patients. However, delayed awakening and respiratory adverse events might warrant special attention in the elderly patients.

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