The comparison of spinal anesthesia with general anesthesia on the postoperative pain scores and analgesic requirements after elective lower abdominal surgery: A randomized, double-blinded study

Abstract

• Background: The aim of this study was to compare the postoperative pain scores and morphine requirements between spinal anesthesia (SA) with hyperbaric bupivacaine 0.5% and general anesthesia (GA) with 1 minimal alveolar concentration (MAC )of isoflurane in 50% N2O and O2 after elective lower abdominal surgery.
• Materials and Methods: In this randomized clinical trial, 68 patients with American Society of Anesthesiologists (ASA) I or II undergoing lower abdominal surgery were randomly assigned to have elective lower abdominal surgery under SA (n = 34) or GA (n = 34). The SA group received 3 cc of 0.5% hyperbaric bupivacaine (15 mg), at L3–L4 interspace intrathecally and also 2 mic/kg fentanyl and 0.15 mg/kg  morphine intravenously for intraoperative analgesia. In the GA group, induction of anesthesia was carried out with Na thiopental 6 mg/kg body weight, fentanyl 2 mic/kg body weight, morphine 0.15 mg/kg, and atracurium 0.6 mg/kg body weight, and then, trachea was intubated. The primary outcome was postoperative pain scores at rest and under stress on a visual analog scale and the secondary outcome was morphine requirement by the patients. Outcome measures were recorded at 2, 4, 6, 12, and 24 h postoperatively. The duration of postanesthesia care unit (PACU) and hospital stay were recorded. Intraoperative parameters, postoperative pain scores, complications, recovery time, and the duration of hospital stay at follow up were compared between the two groups.
• Results: Patients in SA group had significantly lower scores of a postoperative pain at rest (3.4 ±  1.6 and 4.1 ±  1.2 at 2 and 4 h postoperatively vs. 5.2 ±  1.5 and 5.8 ±  0.9 in the GA group with p < 0.05), but there were no significant differences between both groups for scores of postoperative pain at 6, 12, and 24 h. The amount of morphine requirement in 6 h postoperatively was significantly lower in the SA group (10.2 ± 4.3 mg vs. 15.6 ± 5.6 mg in the GA group with p < 0.05), but there were not significant differences between the two groups after 6 h postoperatively. The duration of PACU stay was shorter for the GA group than the SA group (75 ±6 vs. 126 ± 12 min, p < 0.001), but there was no significant differences between the duration of hospital stay between the two groups (1.8 ± 0.6 vs. 2.1 ± 0.8 days).
• Conclusion: Although in patients undergoing elective lower abdominal surgery with SA may have lower pain scores and also lower morphine requirement in the first 6 h postoperatively, but after that there were no significant differences between SA and GA regarding postoperative pain scores and analgesic requirements and so more attention should be given to their postoperation pain relief.
• Key words: Analgesic requirements, general anesthesia, postoperative pain, spinal anesthesia