A Height-Based Dosing Algorithm of Bupivacaine in Spinal Anesthesia for Decreasing Maternal Hypotension in Cesarean Section Without Prophylactic Fluid Preloading and Vasopressors: A Randomized-Controlled Non-Inferiority Trial.

BACKGROUND

There is a high incidence of maternal hypotension in spinal anesthesia for cesarean section. The aim of the study is to investigate whether there is a height-based dosing algorithm of bupivacaine that provides adequate anesthesia with less maternal hypotension.

METHODS

There were 2 groups of 280 parturients who did not receive prophylactic fluid preloading: Test and Conventional group. In Test group, a height based dosing algorithm was used to confirm the dose of bupivacaine in parturients without prophylactic vasopressors. In the Conventional group, a constant dose of bupivacaine was used. The complications and quality of anesthesia were evaluated.

RESULTS

In the Conventional group, the shorter participants had higher incidence of hypotension, faster sensory block time, and more participants with complete motor block ( = 0.030, 2.957 × 10, and 0.012). In the Test group, the incidence of hypotension, sensory block time, and number of participants with complete motor block did not change with height ( = 0.199, 0.617, and 0.209). The height-based dosing algorithm of bupivacaine decreased the incidence of hypotension ( = 0.004), induced lower sensory block level and less degree of motor block ( = 3.513 × 10 and 5.711 × 10). The quality of analgesia, quality of muscle relaxation, and degree of intraoperative comfort were similar in both groups ( = 0.065, 0.498, and 0.483).

CONCLUSIONS

The height influences the dose of bupivacaine in spinal anesthesia; without prophylactic fluid pre-loading and vasopressors, the height-based dosing algorithm of bupivacaine is suitable, and meets the cesarean section' requirement with less maternal hypotension.

CLINICAL TRIAL REGISTRATION

www.ClinicalTrials.gov, identifier: NCT03497364.