Minimum Effective Dose (ED and ED) of Intrathecal Hyperbaric Bupivacaine for Cesarean Delivery: A Systematic Review.

Lowering the dose of the local anesthesia significantly reduces the risks of spinal anesthesia-induced hypotension in an elective cesarean delivery. Determination of the mean effective dose of hyperbaric bupivacaine will aid clinicians in managing maternal hypotension. The systematic search of studies evaluating the mean effective dose of hyperbaric bupivacaine yielded 10 clinical trials reporting the minimum effective dose in 50% (ED) and 95% (ED) of patients. The up-down method and the random allocation design were the dose-finding strategies used in all trials included in the review. The calculated ED and ED of bupivacaine varied according to different patient subgroups. The estimated ED of hyperbaric bupivacaine with or without opioid ranged from 4.7 mg to 9.8 mg. The calculated ED ranged from 8.8 mg to 15 mg. Doses at the level of ED minimized spinal anesthesia-induced hypotension yet increased intraoperative pain supplementation, whereas doses at the level of ED provided adequate surgical anesthesia with increased risk of maternal hypotension. Furthermore, the addition of intrathecal administration of opioids reduced local anesthetic doses. In the clinical setting, low-dose spinal anesthesia should be used only in combination with the combined spinal-epidural technique.