[Preemptive analgesia with epidural bupivacaine and S(+)ketamine in abdominal hysterectomy.].

BACKGROUND AND OBJECTIVES This study investigates the ability of epidural S(+)ketamine, NMDA receptor antagonist, plus local anesthetic (bupivacaine) injection to promote preemptive analgesia in patients undergoing total abdominal hysterectomy, when this solution is administered before surgical incision. METHODS Participated in this prospective double-blind study 30 patients were randomly assigned in two equal groups. Epidural injection and catheter insertion were performed at L1-L2 interspace. Group 1 (G1) patients received 17 mL bupivacaine 0.25% plus 3 mL S(+)ketamine (30 mg), 30 min before surgical incision, followed by 20 mL saline 30 min after incision. Group 2 (G2) patients received 20 mL saline 30 min before surgical incision, followed by 17 mL bupivacaine 0.25% plus 3 mL S(+)ketamine (30 mg) 30 min after incision. General anesthesia was induced with propofol, pancuronium, O2 and isoflurane. Postoperative analgesia consisted of epidural fentanyl plus bupivacaine bolus with 4h minimal interval. If necessary, IV dipyrone supplementation was administered. Patients were evaluated for analgesia by a verbal and numeric scale (at recovery and every six hours until 24 postoperative hours). Time to first analgesic request and total analgesic requirements were recorded. RESULTS There were no significant differences between groups in time to first analgesic request, total analgesic consumption and numeric or verbal scale pain scores. CONCLUSIONS This study failed to demonstrate a preemptive effect of epidural administration of bupivacaine and S(+)ketamine in the doses tested for abdominal hysterectomy.