The Efficacy and Safety of Dexmedetomidine for Sedation During Surgery Under Epidural or Spinal Anesthesia: A Randomized, Double-Blind, Placebo-Controlled Study

Abstract

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. 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. 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. 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.