Optimal Infusion Rates of Remifentanil during Propofol Anesthesia for Monitored Anesthesia Care in Patient Undergoing Varicose Vein Endovenous Laser Therapy

Abstract

Propofol and remifentanil are both rapid and short-acting drugs that can be used for sedation and analgesia during monitored anesthesia care (MAC). This study was designed to determine the optimal infusion rates of remifentanil during propofol anesthesia in patient undergoing the varicose vein endovenous laser therapy. Methods: In this randomized, double-blind study, we evaluated the effects of different remifentanil infusion rates on the requirement doses of propofol, level of sedation, intraoperative recall, respiratory and cardiovascular variables, and recovery. Forty consenting ASA physical status I or II patients undergoing endovenous laser therapy with 1% lidocaine skin infiltration were randomly assigned to one of two treatment groups. All patients received midazolam 0.05 mg/kg intravenously for premedication. Remifentanil was infused at 0.05 or 0.10μg/kg/min during the anesthesia. Sedation was evaluated using the Observer's Assessment of Alertness/Sedation (OAA/S) scale at 5 min intervals by a blinded observer and continuous BIS monitor. The propofol infusion was started from the rate, 3 mg/kg/hr, and subsequently varied to maintain patient comfort, sedation, stable cardiovascular and respiratory function. Results: Higher infusion rates of remifentanil (0.10μg/kg/min) produced significant respiratory depression (P ＜ 0.05). The infused total doses of propofol were not different from each other significantly. Conclusions: This study demonstrated that administration of propofol at 3.4 ± 1.3 mg/kg/hr with a remifentanil infusion at 0.05μg/kg/min is the optimal dosing regimen to provide sedation, analgesia and amnesia with a low incidence of side effects, such as respiratory depression in the patients premedicated with midazolam undergoing varicose vein endovenous laser therapy.