Comparison of the efficacy of two different doses of low-dose bupivacaine for spinal anesthesia in patients undergoing cesarean operations on anesthesia quality and intraoperative hemodynamic parameters

Aims: The primary aim of this study was to investigate the effects of two different low-dose bupivacaine used in cesarean operations on intraoperative hemodynamic parameters, and the secondary aim was to evaluate the time of anesthesia onset, motor block scores, and the need for vasopressor agent. Methods: This prospective randomized double-blind study was performed on 72 pregnant women who underwent cesarean surgery. We randomized the patients into two groups, Group A and Group B, and performed a combined spino-epidural anesthesia. Group A received a solution containing 5 mg isobaric bupivacaine+15µg fentanyl+0.5 isotonic (total volume 1.8 ml) and Group B received a solution containing 7.5 mg bupivacaine+15µg fentanyl (total volume 1.8 ml) over a period of 30 seconds. Vital signs were recorded before the spinal anesthesia and perioperatively. Demographic data, hemodynamic parameters, vital signs and side effects, operation duration, time interval from spinal injection to placement in the supine position, Apgar scores, time interval from spinal injection to delivery, analgesia duration, the degree of motor block immediately before the surgery and at the end of the operation, maximum block level, time for sensory block to reach T6 dermatome level after spinal injection and postoperative side effects were recorded. We recorded the postoperative time to resolution of motor block and the time to regression of sensory block to T10. Results: There was no statistically significant difference between the two groups in terms of demographic data, anesthesia duration, surgery duration, time interval from spinal injection to placement in the supine position, time interval from spinal injection to delivery, analgesia duration, time for sensory block to reach T10, T6, and T4 dermatomes, 1- and 5-minute (min) Apgar scores, and preoperative Bromage scores. While the mean time to resolution of motor block was 159.69±65.72 min in Group B, the mean time to resolution of motor block was 123.13±64.93 min in Group A and the difference was statistically significant (p=0.02). Hypotension was observed in 19 patients (52.77%) in Group A and 29 patients (80.55%) in Group B (p=0.012). A statistically significant difference was detected between the two groups in terms of the need for vasopressor agent and the amount of ephedrine used (p=0.012, p=0.021, respectively). Postoperative Bromage score was 1.25±0.93 in Group A while it was 2.47±1.27 in Group B (p=0.000). Conclusion: In patients undergoing CS, we found that intrathecal administration of 5 mg isobaric bupivacaine combined with 15 mcg fentanyl and 0.5 ml isotonic not only provided adequate anesthesia but also better preserved hemodynamic stability and significantly shortened the time to resolution of motor block. We believe that this dose can be used safely in patients undergoing CS. Further studies using varying intrathecal bupivacaine doses are necessary to validate our findings.