Prophylactic calcium reduces postspinal hypotension during cesarean delivery in preeclamptic women receiving magnesium supplements: Study

Preeclamptic women, in addition to traditional antihypertensive medications, often receive magnesium supplementation and are at increased risk of postspinal hypotension Postspinal hypotension increases the risk of fetomaternal morbidity.

Calcium is a physiological antagonist of magnesium in vascular smooth muscle. Therefore, the study hypothesized that calcium is better suited for preserving systemic vascular resistance and preventing postspinal hypotension during cesarean delivery.

The study aimed to evaluate the effect of prophylactic calcium administration on postspinal hypotension in preeclamptic women receiving magnesium supplementation. This prospective, randomized, placebo-controlled, double-blinded, two-arm parallel trial was conducted in preeclamptic women receiving magnesium sulfate supplementation undergoing cesarean delivery. The women were randomized to receive intravenous calcium or a placebo (normal saline) before spinal anesthesia. The study drug (calcium gluconate 500 mg or normal saline) was administered over 15 minutes and ended immediately before spinal anesthesia. The primary outcome measure was the incidence of postspinal hypotension, and secondary outcome measures were postpartum blood loss and maternal and neonatal outcomes.

Results: A total of 100 women (50 each calcium and placebo arm) completed the study. The baseline demographic variables, mean blood pressure and heart rate were comparable. The incidence of postspinal hypotension was significantly lower in the calcium arm compared to the placebo arm (32% vs 60%; Relative risk [95% CI]; 1.87 [1.18–2.97]; P=.007). The mean phenylephrine requirement (5.60±14.59 vs 14.80±22.42 mcg; P=.01) and mephentermine requirement (3.30±5.11 mg vs 5.82±4.97 mg; P=.008) was significantly lower in the calcium group. Furthermore, the calcium group's mean postpartum blood loss was significantly lower (406.90±94.34 vs 472.20±122.49 ml, P=.004). However, the Neonatal Intensive Care Unit admission rate, Apgar score, umbilical artery PH, and maternal serum calcium were comparable. Prophylactic calcium infusion significantly reduces the incidence of postspinal hypotension during cesarean delivery in preeclamptic women receiving magnesium supplementation. Furthermore, the effect of prophylactic calcium in decreasing postpartum blood loss is encouraging. However, large trials are required to validate the findings of this study.

Reference:

Navin Kumar Yadav, Suman Lata, Nivedita Jha, Deepak Chakravarthy, Ajay Kumar Jha, Role of prophylactic intravenous calcium in prevention of postspinal hypotension among women with preeclampsia undergoing cesarean delivery: a placebo controlled randomized clinical trial. American Journal of Obstetrics & Gynecology MFM, Volume 7, Issue 1, 2025, 101541, ISSN 2589-9333, https://doi.org/10.1016/j.ajogmf.2024.101541.