The Effect of Intravenous Infusion of Magnesium Sulfate during Surgery on Pain Reduction after Caesarean Section with Spinal Anesthesia

Background: This study evaluated the effect of infusion of magnesium sulfate during surgery on pain and Parturient morbidity after caesarean section. Methods: In this randomized controlled double-blind clinical trial, 40 pregnant women ASA I, II, who were candidates for caesarean under spinal anesthesia were allocated into two groups by block random methods; the intervention group received magnesium sulfate with 40 mg/kg as loading dose and infusion of 15 mg/kg/h until the end of the surgery and the placebo group received normal saline with similar volume. Pain intensity was measured and recorded by numerical rating scale (NRS) at the baseline (motor block started to wear off) and 30 minutes, 4, 12 and 24 hours later. Results: Magnesium sulfate decreased the mean of blood pressure 3 and 5 minutes after spinal anesthesia and 15 minutes into recovery, decreased the mean of pain intensity (p < 0.001) and painkiller consumption and also reduced the interval before toleration of oral liquids for the time after surgery (10 hours and 53 minutes vs. 13 hours and 6 minutes, p < 0.05). Side effects and the Apgar score of neonates at the first and fifth minutes after delivery had no significant difference between both groups (p < 0.05). Conclusions: Infusion of magnesium sulfate during surgery would decrease pain intensity and postoperative ileus and also would increase the interval before painkiller request by the mother with the least side effects for the mother and the neonate.