The effect of different epidural i̇nitial volumes on postoperative pain in cesarean section

Purpose: We aimed to compare the effect of different epidural initiation volumes on postoperative pain scores, local anesthetic requirements, and motor block in patients who underwent patient controlled epidural analgesia (PCEA) for postoperative pain after cesarean section. Materials and Methods: Eighty-one pregnant women, with ASA physical class II, and aged 18-45 years were included into the study. Standardized monitoring was performed after the unpremedicated cases were taken into the operating room. A catheter was placed for combined spinal epidural anesthesia from L3-4 or L4-5 levels in the sitting position. The spinal block was obtained by intrathecal administration of 10 mg heavy bupivacaine. Drug administration was initiated, ninety minutes after the block was obtained, from the epidural catheter. The pregnant women were randomly divided into three groups using the envelope method. In Group 20 (n = 27): 20 mL 0.625% bupivacaine + 2 μg/mL fentanyl, in Group 10 (n = 27): 10 mL 0.625% bupivacaine + 2 μg/mL fentanyl, and in Group 5 (n=27): 5 mL 0.625% bupivacaine + + 2 μg/mL fentanyl solution was administered. For each group, 0.625% bupivacain + 2 μg/mL fentanyl, was administered with a patient-controlled analgesia (PCA) device through the epidural catheter with the following parameters; basal infusion: none, bolus dose: 5 mL, lockout time: 15 min. The drugs were administered in 5 mL divided doses from the epidural catheter and the first 5 mL test was accepted as a dose. The visual analog scale (VAS) rest, VAS motion, first PCEA demand time, the number of PCEA requirement per hour, morphine requirement, nausea-vomiting, itching, motor block, hypotension and total consumed analgesic and ephedrine amounts of the patients were recorded in the recovery room and at postoperative 2, 4, 6, 12 hours. Results: Time to first analgesic requirement (first PCA time) was found 44.89 ± 26.73 min in Group 5, 85.93 ± 64.51 min in Group 10, and 97.96 ± 66.17 min in group 20. Time to first analgesic requirement was significantly longer in Group 10 and Group 20 than in Group 5 (p<0.05). The analgesic requirement in the first 2 hours (number of PCA demands) was found 3.30 ± 1.4 in Group 5, 2.07 ± 1.73 in Group 10 and 1.41 ± 1.57 in Group 20. The analgesic requirement in the first 2 hours was significantly lower in the Group 20 than the other groups (p<0.05). The itching score at 6th hour in Group 10 was significantly higher than the other two groups (p <0.05). Conclusion: When we used 20 mL as the epidural initiation volume in our study, we determined that time to first analgesic requirement was longer and the analgesic requirement in the first 2 hours was less than the patients that were administered epidural initial volume of 5 mL and 10 mL.