Adequate Anesthesia and More Effective Analgesia by Adjusted Doses of Bupivacaine during Cesarean Section: A Randomized Double-blind Clinical Trial.

Background: Several adjuvants, added to local anesthetics, were suggested to induce an ideal regional block with high-quality analgesia. The purpose of this study was to evaluate the particular blocking properties of low-dose bupivacaine in combination with meperidine and fentanyl in spinal anesthesia during Cesarean sections.

Methods: A randomized, double-blind clinical trial was conducted at Hafez Hospital affiliated with Shiraz University of Medical Sciences (Shiraz, Iran) from February 2015 to February 2016. A total of 120 pregnant women, who underwent spinal anesthesia during elective Cesarean section were enrolled in the study. Based on block-wise randomization, the patients were randomly assigned to three groups, namely "B" group received 2 mL bupivacaine 0.5% (10 mg), "BM" group received 8 mg bupivacaine and 10 mg meperidine, and "BF" group received 8 mg bupivacaine and 15 µg fentanyl intrathecally. The block onset, the duration of analgesia, and the time of discharge from the post-anesthesia care unit (PACU) were all assessed. Data were analyzed using SPSS software version 21, and P<0.05 were considered statistically significant.

Results: The mean duration of motor blocks in the B group (150 min) were significantly higher than the BM (102 min) and BF (105 min) groups (P<0.0001). In both the BM and BF groups, the duration of sensory and motor blocks was the same. The length of stay in the PACU was significantly longer in the B group (P<0.001) than the BM and BF groups. When meperidine or fentanyl was added to bupivacaine, the duration of the analgesia lengthened (P<0.001).

Conclusion: Intrathecal low-dose spinal anesthesia induced by bupivacaine (8 mg) in combination with meperidine and/or fentanyl for Cesarean section increased maternal hemodynamic stability, while ensuring effective anesthetic conditions, extending effective analgesia, and reducing the length of stay in PACU. IRCT2015013119470N14.