Abstract
BACKGROUND: Only a few studies have been reported on the use of dexmedetomidine for sedating surgical patients requiring epidural or spinal anesthesia. We conducted a randomized, double-blind, placebo-controlled, parallel-group study at 12 hospitals in Japan. METHODS: Adult patients were randomly allocated to receive an intravenous administration of placebo or dexmedetomidine at 0.067, 0.25, 0.5 or 1.0 µg/kg over 10 min after epidural or spinal anesthesia. All dexmedetomidine groups received dexmedetomidine 0.2-0.7 µg/kg/h to maintain an Observer's Assessment of Alertness/Sedation Scale (OAA/S) score of ≤ 4; however, propofol was administered to rescue patients who exceeded this score. Surgery was then started 15 min after study drug infusion in patients with OAA/S score of ≤ 4. The primary endpoint was the percentage of patients not requiring rescue propofol to achieve and maintain an OAA/S score of ≤ 4. RESULTS: Of the 120 enrolled and randomized patients, 119 were treated the study: 22 received placebo and 97 received dexmedetomidine (23-25 patients per dose). Significantly more patients did not require propofol in the dexmedetomidine 0.5 and 1.0 µg/kg groups (68.0% and 80.0%, respectively) compared to the placebo group (22.7%) (P = 0.003 and P < 0.001, respectively). Common adverse events (AEs) were protocol-defined respiratory depression, bradycardia and hypotension. There was no significant difference in the incidence of AEs between the dexmedetomidine and the placebo groups. CONCLUSION: We concluded that loading doses of 0.5 and 1.0 µg/kg dexmedetomidine, followed by an infusion at a rate of 0.2-0.7 µg/kg/h, provide effective and well-tolerated sedation for surgical patients during epidural or spinal anesthesia. Clinical trials.gov identifier: NCT01438957.