Effects of adding 5 mg meperidine to 10 mg bupivacaine for spinal anesthesia on postoperative pain in cesarean section surgery

Introduction: Meperidine has the advantages of being widely available and inexpensive. It would be highly cost-benefit if it is used at doses that are without any side-effect. Thus, this study aimed to assess the effect of meperidine 5 mg as an additive to bupivacaine for spinal anesthesia on postoperative pain in cesarean section surgery. Methods: This double-blind randomized clinical trial was performed on 40 patients aged 20-40 yr. They were in classes 1 or 2 according to the American Society of Anesthesiologists (ASA) physical status classification system and were scheduled for elective cesarean surgery under spinal anesthesia. Patients were randomly allocated into two groups according to whether meperidine or normal saline was used as an additive to bupivacaine for spinal anesthesia. All patients with pre-existing or pregnancy-induced hypertension, known fetal abnormality or allergy to bupivacaine or meperidine were excluded. Postoperative analgesia was compared between the two groups immediately and 2, 12, 24 hours after surgery. Also, the need for antiemetic was compared between the groups. The collected data was analyzed in SPSS software (version 16) using independent t-test, Mann-Whitney, and Chi-square. The significance level for all tests was considered less than 0.05. Results: The severity of postoperative pain 12 and 24 hours after surgery was significantly higher in normal saline group. There was no significant difference in incidence of pruritus, nausea and vomiting between the two groups. Conclusions: Addition of meperidine 5 mg to intrathecal bupivacaine is associated with increased duration and quality of postoperative analgesia but has no significant effect on severity and incidence of pruritus, nausea and vomiting.