Spinal or Intravenous Dexmedetomidine for Spinal Anesthesia with Chloroprocaine in Ambulatory Knee Arthroscopies: A Double-Blind Randomized Trial

PURPOSE: Chloroprocaine provides spinal anesthesia for day-case surgery lasting up to 40 minutes. Intravenous and spinal dexmedetomidine can prolong spinal anesthesia, but no data are available for the combination with chloroprocaine. This double-blind randomized controlled trial compares chloroprocaine with spinal or intravenous dexmedetomidine regarding block characteristics, micturition, and discharge times. PATIENTS AND METHODS: After ethical approval and informed consent, 135 patients scheduled for knee arthroscopy were randomized to receive either 40mg spinal chloroprocaine (Chloro-group), 40mg chloroprocaine with 5 mcg spinal dexmedetomidine (Spinal Dex-group) or 40mg chloroprocaine with 0.5 mcg/kg IV dexmedetomidine (IV DEXgroup). Block characteristics, hemodynamic variables and the use of analgesics were registered. Voiding and discharge times were noted. A scoring system was used for micturition problems and sedation. Transient neurological symptoms (TNS) and other late side effects were evaluated after one week. RESULTS: Demographic data were similar between groups. Block onset times and intensity of motor block were comparable between groups. The time to L2 and Bromage 1 regression was prolonged in the SpinalDEx-group by approximately 30 minutes compared to the other groups (p < 0.01). First voiding as well as discharge from the hospital was prolonged in the Spinal Dex-group by approximately 40 minutes p < 0.01. There was no significant difference between groups regarding treatment of hypotension, sedation, micturition problems or the use of postoperative analgesics (P > 0.8). One patient experienced TNS. CONCLUSION: Intrathecal but not intravenous (0.5 mcg/kg) dexmedetomidine can prolong chloroprocaine (40mg) spinal anesthesia when surgery is expected to last over 40 minutes. Despite a similar incidence of adverse effects, this also led to a postponed hospital discharge time.