Median effective concentration of remifentanil in target controlled infusion for smooth tracheal extubation during emergence from general anesthesia in elderly patients.

STUDY OBJECTIVE: To determine the median effective concentration (EC50) of remifentanil during targeted-controlled infusion for smooth tracheal extubation during emergence from total intravenous anesthesia in elderly patients.

DESIGN: Prospective, Dixon up-and-down method.

SETTING: Postoperative emergence.

PATIENTS: Twenty-four American Society of Anesthesiologists grade I-II female elderly patients undergoing elective jaw cyst surgery.

INTERVENTIONS: The EC50 of remifentanil for smooth emergence was calculated by the Dixon up-and-down method.

MEASUREMENTS: The EC50 and 95% confidence intervals were analyzed by probit analysis using logistic regression. Vital signs (mean arterial pressure, heart rate, oxygen saturation, and end-tidal carbon dioxide partial pressure), postanesthesia recovery score, visual analogue pain scale, and adverse effects were monitored. Mean arterial pressure and heart rate were compared between patients with smooth extubation vs those with failed smooth extubation.

MAIN RESULTS: The Dixon up-and-down method showed that the EC50 of remifentanil for smooth tracheal extubation during emergency from anesthesia was 0.94 ng/mL in female elderly patients. The probit analysis showed that the EC50 of remifentanil was 0.99 ng/mL (95% confidence interval, 0.52-1.51 ng/mL). Heart rate and mean arterial pressure were significantly lower in patients with smooth extubation as compared with those with failed smooth extubation at 0 minute (at extubation) as well as 1 and 5 minutes after extubation (P< .05).

CONCLUSIONS: Target infusion of remifentanil at 0.94 ng/mL could effectively inhibit tracheal extubation-related cough response and cardiovascular responses in 50% of the female elderly patients without delaying recovery from anesthesia, which could ensure smooth tracheal extubation during emergence from anesthesia.