The influence of preemptive spinal anesthesia on postoperative pain

Study Objective: To examine the influence of spinal anesthesia on postoperative pain and postoperative opioid requirements. Design: Prospective randomized study. Setting: Bnai-Zion Medical Center, Haifa, Israel - a government hospital. Measurements and Main Results: 30 ASA physical status I and II unpremedicated women undergoing elective total abdominal hysterectomy were randomly allocated into two groups of 15 patients each using a sealed envelope technique. Patients in Group 1 were given a subarachnoid injection of 12 mg hyperbaric bupivacaine and after 10 minutes general anesthesia was induced. Patients in Group 2 received only general anesthesia. Anesthesia was induced with midazolam and maintained with oxygen, N₂O, isoflurane, and pancuronium. No opioids were given intraoperatively. Postoperatively patient- controlled analgesia (PCA) with morphine was initiated in both groups (1 mg. mL^-1, bolus dose 1 mg, lockout interval 10 minutes, and background infusion 1 mg.mL^-1) at patient first request for analgesic. Pain was assessed over 24 hours by cumulative morphine dose and visual analog score (VAS). Postoperative PCA morphine consumption at 2, 6, and 24 hours following patient first request for analgesic for Groups 1 and 2 were: 3.1 ± 1 mg versus 7.2 ± 3 mg (p = 0.04), 13.4 ± 2 mg versus 17.2 ± 4 mg (p = 0.03) and 35.9 ± 8 mg versus 47.7 ± 8 mg in Group 2 (p = 0.04). VAS scores at 4, 6, 12, and 24 hours postoperatively were not significantly different between the two groups. Conclusions: Preoperative neural blockade may reduce postoperative analgesic requirements. (C) 2000 by Elsevier Science Inc.