Remifentanil versus propofol as adjuncts to regional anesthesia. Remifentanil 3010 Study Group

To compare the safety and efficacy of remifentanil and propofol as adjuncts to regional anesthesia in patients undergoing orthopedic or urogenital surgery.

Prospective, randomized study.

Multicenter university hospitals.

107 ASA physical status I, II, and III adult patients who underwent orthopedic or urogenital surgery with axillary, ankle, or spinal block.

Patients were randomized to receive either an infusion of remifentanil 0.2 microg/kg/min or propofol 100 microg/kg/min 5 minutes before nerve block placement. The infusions were decreased by 50% on block completion, increased by 50% for patient discomfort, and decreased by 50% for hypoventilation (< 8 breaths/min) or hemodynamic instability.

Pain, discomfort, anxiety, and sedation were assessed by both patient and investigator. Vital signs and adverse events were recorded. Fewer patients in the remifentanil group experienced pain during block placement (6%), and were oversedated (7%) than patients in the propofol group (23% and 26%, respectively; p < 0.05). Hypoventilation during and after block placement (21% and 25%, respectively) and nausea and vomiting during and after block placement (60% and 21%, respectively) were more common in the remifentanil group than in the propofol group (0% and 3%; 17% and 6%, respectively; p < 0.05). The incidence of hypoventilation in remifentanil-treated patients was higher in patients over 65 years of age (p < 0.05), but was transient, resolving within minutes of discontinuing the infusion.

At the doses studied, remifentanil was more effective than propofol in minimizing pain without producing excessive sedation. Remifentanil was associated with more transient respiratory depression and short-term nausea. Our findings indicate that the initial remifentanil rate should be 0.1 microg/kg/min (50% lower than the study's initial rate) and should be further decreased an additional 50% in the elderly to minimize adverse effects.