Intrathecal magnesium sulfate does not reduce the ED50 of intrathecal hyperbaric bupivacaine for cesarean delivery in healthy parturients: a prospective, double blinded, randomized dose-response trial using the sequential allocation method

Abstract

BackgroundAddition of intrathecal magnesium sulfate to local anesthetics has been reported to potentiate spinal anesthesia and prolong analgesia in parturients. The current study was to determine whether intrathecal magnesium sulfate would reduce the dose of hyperbaric bupivacaine in spinal anesthesia with bupivacaine and sufentanil for cesarean delivery.MethodsSixty healthy parturients undergoing scheduled cesarean delivery were randomly assigned to receive spinal anesthesia with 0.5% hyperbaric bupivacaine and 5 μg sufentanil with either 0.9% sodium chloride (Control group) or 50% magnesium sulfate (50 mg) (Magnesium group). Effective anesthesia was defined as a bilateral T5 sensory block level achieved within 10 min of intrathecal drug administration and no additional epidural anesthetic was required during surgery. Characteristic of spinal anesthesia and the incidence of side effects were observed. The ED50 for both groups was calculated using the Dixon and Massey formula.ResultsThere was no significant difference in the ED50 of bupivacaine between the Magnesium group and the Control group (4.9 mg vs 4.7 mg) (P = 0.53). The duration of spinal anesthesia (183 min vs 148 min, P < 0.001) was longer, the consumption of fentanyl during the first 24 h postoperatively (343 μg vs 550 μg, P < 0.001) was lower in the Magnesium group than that in the Control group.ConclusionsIntrathecal magnesium sulfate (50 mg) did not reduce the dose requirement of intrathecal bupivacaine, but can extend the duration of spinal anesthesia with no obvious additional side effects.Trial registrationThis study was registered with Chinese Clinical Trial Registry (ChiCTR) on 15 Jul. 2014 and was given a trial ID number ChiCTR-TRC-14004954.

Prophylactic infusion of phenylephrine increases the median effective dose of intrathecal hyperbaric bupivacaine in cesarean section

“…[ 11 ] Our previous study indicated that the ED 50 values of intrathecal hyperbaric bupivacaine (along with 5 μg sufentanil) with or without magnesium sulfate were 4.9 or 4.7 mg, respectively, in cesarean section. [ 12 ] These results were similar to those seen in this study. However, in a dose–response study conducted by Ginosar et al, the ED 50 of intrathecal hyperbaric bupivacaine (mixed with morphine 200 μg and fentanyl 10 μg) was 7.6 mg in cesarean section.…”

“…According to Tyagi et al [ 11 ] and our prior study, [ 12 ] the sample size is regarded as adequate once 6 pairs of reversals of sequence are achieved when using the up-down method to determine the ED 50 of intrathecal bupivacaine. Each group achieved more than 6 pairs of reversals of sequence after 30 patients enrolled in this study.…”

Neoadjuvant Chemotherapy Does Not Decrease the Dose Requirement of Propofol for Inducing the Loss of Consciousness in Patients with Breast Cancer: A Prospective Study

“…The onset time and dose of LOC was also studied. According to Tyagi and our previous study, a sample size of 30 patients for each group was determined in the current study, because sample size is regarded as adequate when 6 pairs of reversal of sequence are achieved [5,6]. The Dixon and Massey formula was applied to calculate the EC50 for both groups [7].…”

Comparison of the ED50 and ED95 of Intrathecal Bupivacaine in Parturients Undergoing Cesarean Delivery With or Without Prophylactic Phenylephrine Infusion

“…An effective dose was defined as a bilateral T5 or higher sensory block achieved within 10 minutes of intrathecal drug administration without the need for epidural supplementation. 11 In the event of insufficient sensory block, 5-mL bolus doses of 2% lidocaine separated by 5-minute intervals were administrated via the epidural catheter until achieving adequate anesthesia.…”