Height-adjusted dose of intrathecal bupivacaine on surgical anesthesia for the cesarean section

Background: In the spinal anesthetic technique, local anesthetic dose (concentration and volume) is the main determinant of its adequacy and success of block to be achieved. The lack of pain during surgical intervention rather than on dermatome sensory block level is considered to be an appropriate indicator of surgical anesthesia. Spinal anesthesia is the most common anesthetic technique to provide anesthesia for the elective or emergent cesarean section (CS). However, spinal block-induced maternal hypotension is the most common adverse effect during single-shot spinal anesthesia. In our study, we aim to study the height-adjusted dose of 0.5% Bupivacaine Heavy (BH) in achieving surgical anesthesia and its effect on maternal hypotension. Participants and Method: One hundred parturients scheduled for elective CS were enrolled and were compared to the parallel arms of parturients receiving conventional BH. Fifty parturients in each group were included. In the conventional group (B), participants received spinal block with 12 mg of 0.5% BH, and in the height adjusted-dose group (H), participants received a dose of 0.5% BH in 0.06 mg per centimetre height. A sensory block level of T6 dermatome or higher was consider adequate to start surgery. The adequate surgical anesthesia is considered to be achieved if cesarean delivery can be performed without supplementary analgesia. The need of supplementary analgesia, conversion to general anesthesia, or no block till 15 min of intrathecal BH is considered spinal failure. Results: 4% of the height-adjusted dose group have a low block level. Two cases complained of pain, and of them, one received supplementary analgesia and one was converted to general anesthesia. Systolic hypotension of a maternal blood pressure of less than 90 mm Hg was found in 19 (38%) and 10 (20%) in the conventional group and HAD group, respectively, which was highly significant statistically (p value 0.001%). Conclusion: Intrathecal hyperbaric bupivacaine in height adjusted 0.06 mg per cm height of patient can achieve surgical anesthesia with maintainance of systolic blood pressure. However, low dosing of intrathecal BH has higher cases of block failure in comparison to the conventional fixed dose regime of spinal anesthesia.