Minimum effective volume of bupivacaine in spinal anesthesia for elective cesarean section. Does it differ with height? A non-randomized parallel study

Abstract

Background: Spinal anesthesia is the preferred anesthetic technique for elective Cesarean deliveries. Hypotension is the most common side-effect and has both maternal and neonatal consequences. This study aims to determine the minimum effective volume of hyperbaric bupivacaine 0.5% with fentanyl in 90% of parturients (MEV90) with different height groups undergoing cesarean section. Patients and Methods: Parturients scheduled for elective cesarean section under spinal anesthesia were divided into 3 groups according to their height (ht), group 1 including those with height between 150 and 159 cm, group 2 with ht between 160 and 169 cm and group 3 patients with ht between 170 and 179 cm. The starting volumes were 2.5, 2.6 and 2.7 ml respectively. We identified 3 responses to the injected volume and the volume given to each parturient depends on the response of the previous one. Every patient was assessed for hemodynamics, degree of sensory and motor blocks. Results: Demographically, all the groups were comparable. The study was completed after recruiting 201 patients. The MEV90 for group 1 was approximately 2.62 ml (95% CI, 2.59-2.65 ml), 2.76 ml for group 2 (95% CI, 2.73-2.77 ml) and 2.80 for group 3 (95% CI, 2.76-2.81 ml). None of the babies had an Apgar score below 7 at 1 and 5 min after birth in the 3 groups. Conclusion: The volumes of hyperbaric 0.5% bupivacaine with fentanyl which produced effective spinal block in 90% of parturients undergoing cesarean deliveries were 2.62, 2.76 and 2.8 ml in the 3 different height groups respectively.

Study on MEV90 of 0.5% ropivacaine for US-guided caudal epidural block in anorectal surgery

“…This fact prompted researchers to investigate the MEV of ropivacaine, which played a role in the CEB for anorectal surgery while taking gender into account. This fact was also used to justify recommending a lower initial volume of women in this study ( 30 , 31 ). The current study is the first to determine the MEV90 of 0.5% ropivacaine for the CEB for anorectal surgery using the extent of the neural blockade as the primary evaluation index.…”

Minimum effective volume of local anesthetic in peribulbar block: does it differ with the eyeball axial length?

“…BCD has been previously validated by prior studies to investigate MEV50 and MEV90 of local anesthetics in regional anesthesia 23 we used this same technique. 24 …”

A Comparative Study on Three Different Doses of Fentanyl with Bupivacaine in Spinal Anaesthesia in Caesarean Section

“…For caesarean section, the usual intrathecal dose of hyperbaric bupivacaine is 10-12 mg. But even with recommended dose, there have been reports of long duration of motor block and sensory block along with hemodynamic derangements 19 due to high dose of intrathecal bupivacaine resulting in delayed recovery 20,21,15 and hence, discharge from post anaesthesia care unit. In order to avoid these, a low dose bupivacaine with several adjuncts has been tried.…”