Hemodynamic effects of oral nifedipine in preeclamptic hypertensive emergencies.

Abstract

Our purpose was to evaluate the hemodynamic effects of oral nifedipine in preeclamptic hypertensive emergencies. A prospective observational study of the hemodynamic effects of oral nifedipine was conducted with severely preeclamptic patients receiving magnesium sulfate infusion during a hypertensive emergency. Patients were eligible for the study if systolic blood pressure was > or = 170 m Hg or the diastolic blood pressure was > or = 105 mm Hg on repeat measurements 15 minutes apart at > or = 24 weeks' gestation. Nifedipine was given with an initial dose of 10 mg orally followed by 20 mg orally every 20 minutes until systolic blood pressure was > 160 mm Hg and the diastolic blood pressure was < 100 mm Hg, or for a total of five doses. Patients were hemodynamically monitored in the lateral recumbent position by thoracic electrical bioimpedance before during, and after oral nifedipine dosing. Cardiac index, systemic vascular resistance index, mean arterial pressure, heart rate, and stroke index were all recorded at baseline and during treatment. Data were analyzed by analysis of variance for repeated measures (alpha 0.05) and paired t tests, baseline versus 15 minutes (alpha 0.01). Ten severely preeclamptic patients at 33.2 +/- 3.0 (mean +/- SD) weeks' gestation were enrolled in the study. Mean arterial pressure measurements taken at baseline, 0.25, 0.5, 1, and 4 hours were 133 +/- 10, 119 +/- 8, 109 +/- 8 89 +/- 12, and 100 +/- 13 mm Hg (mean +/- SD, p < 0.0001, analysis of variance repeated measures). Cardiac index increased over time (p = 0.0011, analysis of variance repeated measures). There was no significant effect on maternal heart rate or stroke index. No periodic fetal heart rate changes were noted. One patient had nausea. Oral nifedipine appears to be an effective antihypertensive agent in preeclamptic hypertensive emergencies. A steady decrease in mean arterial pressure, systemic vascular resistance, and a mirrored increase in cardiac index are noted.