The effect of magnesium on coagulation in parturients with preeclampsia


Harnett MJ, Datta S, Bhavani-Shankar K




Anesth Analg


Preeclampsia is associated with complex coagulation abnormalities that include altered platelet function and consumption and activation of the fibrinolytic system. Magnesium sulfate, which is used as a therapeutic modality for the prevention of seizures in preeclamptic parturients, has anticoagulant and antiplatelet effects. We sought to determine the effects of magnesium on various components of the coagulation system in patients with preeclampsia. We assessed the coagulation status of 18 parturients with preeclampsia being treated with magnesium. The assessment was performed with the thromboelastograph test, which provides an overall assessment of blood coagulation via the coagulation index. Thromboelastography was performed before beginning magnesium therapy and 30 min and 2 h after a 6-g bolus of IV magnesium. The R value (time to first clot formation) was found to be significantly slower (P < 0.05) at 30 min after the magnesium bolus. This result suggests increased coagulant factor activity resulting from the magnesium bolus. However, there was no effect of magnesium on the overall coagulation, as evidenced by the lack of change in the coagulation index either at 30 min or at 2 h after the completion of the initial magnesium bolus. Therefore, this therapy should have no effect on the use of neuraxial techniques. IMPLICATIONS: On the basis of the thromboelastography assessment, we found that the current practice of administering magnesium did not influence overall coagulation in preeclamptic women. Therefore, magnesium administration should not affect the use of neuraxial techniques.