FAVORABLE HEMODYNAMIC-EFFECTS OF MAGNESIUM-SULFATE IN PREECLAMPSIA

OBJECTIVE: Our purpose was to evaluate the hemodynamic effects of magn esium sulfate in preeclamptic and preterm labor patients. STUDY DESIGN : Fifteen preeclamptic patients at 32.4 +/- 3.3 (mean +/- SD) weeks' g estation and 11 preterm labor patients (31.3 +/- 2.8 weeks) were hemod ynamically monitored in the lateral recumbent position by thoracic ele ctrical bioimpedance (BoMed, Irvine, Calif.) before and during high-do se magnesium sulfate bolus and infusion. Cardiac index, systemic vascu lar resistance index, mean arterial pressure, heart rate, and stroke i ndex were all recorded at baseline and during magnesium sulfate infusi on. All patients received a standard crystalloid infusion. Data analys is continued until the patient received epidural placement or other an tihypertensive therapy or was delivered. RESULTS: At baseline the syst emic vascular resistance index was 2465 +/- 718 F . ohm/m(2) and the c ardiac index was 3.6 +/- 1.0 L/min/m(2) for the preeclamptic patients. These were significantly different compared with the preterm labor pa tients, who had a systemic vascular resistance index of 1377 +/- 563 F . ohm/m(2) and 4.6 +/- 1.2 L/min/m(2). Magnesium sulfate infusion res ulted in a rapid, sustained fall in systemic Vascular resistance and a rise in cardiac index in the preeclamptic patient. This effect was ev ident at least 4 hours after initiation of the bolus and infusion. In the preterm labor patients the hemodynamic effects of magnesium sulfat e were minimal and were noted only during the magnesium sulfate bolus. CONCLUSION: Magnesium sulfate infusion appears to have a prolonged he modynamic effect in the preeclamptic patient. Sustained reduction in s ystemic vascular resistance and an increase in cardiac index is found in patients with preeclampsia but not in preterm labor.