RESUMO
BACKGROUND: The intraoperative combination of volatile anesthetics with opioids is a well-accepted technique because of its hemodynamic stability and side effects. This study in adults was designed to determine the pharmacodynamic interactions between different dosages of remifentanil and desflurane in response to skin incision. METHODS: A total of 60 patients were enrolled in this study. Patients were prospectively randomized to receive 0, 0.1, 0.15, or 0.25 microg/kg/min remifentanil. Anesthesia was induced with remifentanil, propofol, and succinylcholine. Thereafter, a group-specific desflurane concentration was administered using Dixon's up-and-down technique. After a "wash out" and equilibration period, patients were observed for defense movements up to 1 minute after skin incision. Mean arterial pressure and heart rate were recorded before induction of anesthesia (baseline), at surgical incision, as well as 2 and 4 minutes thereafter. Time until extubation was assessed after stopping desflurane and remifentanil at the end of the surgery. RESULTS: Remifentanil at 0.1, 0.15, or 0.25 microg/kg/min reduced desflurane requirements by 74, 83, and 90 percent, respectively. The time course of mean arterial pressure did not differ between the study groups. However, compared with the group without remifentanil, heart rate was significantly lower in patients receiving 0.15 or 0.25 microg/kg/min remifentanil. No difference between the groups was observed with regard to extubation time. CONCLUSION: Remifentanil reduces in a dose-dependent manner the desflurane requirements for skin incision without increasing recovery time. An infusion rate higher than 0.1 microg/kg/min results in a significantly decreased heart rate.