Comparison of intrathecal magnesium, dexmedetomidine, or placebo combined with bupivacaine 0.5% for patients with mild pre-eclampsia undergoing cesarean section

BackgroundNeuraxial anesthesia for pre-eclamptic patients undergoing cesarean section is a well-established safe and effective anesthetic technique. Several agents had been studied as adjuvants to commonly used intrathecal drugs.AimThe aim of this prospective, randomized, double-blinded placebo-controlled study is to compare intrathecal magnesium versus dexmedetomidine (DXM) combined with bupivacaine 0.5% for parturients with mild pre-eclampsia undergoing cesarean section in terms of duration of spinal block as a primary outcome and postoperative analgesia and incidence of intraoperative side effects as secondary outcomes.Patients and methodsNinety pregnant women with singleton pregnancies, scheduled for elective cesarean section and diagnosed with mild pre-eclampsia, were enrolled in this prospective, randomized-controlled double-blind study. Lumbar puncture was performed and then patients were allocated to three groups: group D [0.5% hyperbaric bupivacaine 2.5 ml and 0.1 ml (10 μg) preservative-free DXM]; group M [0.5% hyperbaric bupivacaine 2.5 ml and 0.1 ml preservative-free 10% magnesium sulfate (10 mg)]; and group C (0.5% hyperbaric bupivacaine 2.5 ml and preservative-free saline 0.1 ml as a control). Duration of sensory block, motor block, maximal level of sensory block, and duration of spinal anesthesia were recorded. The incidences of hypotension, sedation, nausea, and vomiting were noted every 15 min during surgery. Pain was assessed using a verbal numeric scale from 0 to 10 at 2, 4, 8, 12, 18, and 24 h postoperatively. Intramuscular diclofenac 75 mg was administered for rescue analgesia whenever the pain score was greater than 3. Overall patient satisfaction with anesthesia and analgesia was recorded at 24 h as 1 = excellent; 2 = good; and 3 = poor.ResultsThe three groups were comparable with respect to patients' demographics, gestational age, and duration of surgery. The duration of sensory block, motor block, and spinal anesthesia were prolonged in group M (175.2 ± 19.4, 216.3 ± 12.6, and 200.3 ± 6.4 min) compared with group D (153 ± 4.78, 181.7 ± 7.8, and 160.4 ± 7 min) and group C (150.37 ± 8.8, 171 ± 8.1, and 165 ± 5.83 min), P < 0.001. There was less ephedrine consumption in group M (7.87 ± 0.98 mg) compared with group D (12.4 ± 1.1 mg) and group C (12.3 ± 1.3 mg), P < 0.001. The cumulative requirement of diclofenac over 24 h was significantly less in group M (135.8 ± 27.7 mg) than in group D (183.3 ± 26.7 mg) and group C (187 ± 22.6 mg), P < 0.001. Verbal numeric scale scores in the first 24 h were significantly higher in the control group (group C) than the other two groups.ConclusionThe addition of intrathecal magnesium sulfate (10 mg) to bupivacaine in patients with mild pre-eclampsia undergoing cesarean section prolongs the duration of analgesia and reduces postoperative analgesic requirements without additional side effects compared with intrathecal DXM (10 μg).