A randomized, double-blind, hemodynamic evaluation of nifedipine and labetalol in preeclamptic hypertensive emergencies

Objective: Our purpose was to compare the hemodynamic effects of orally administered nifedipine and intravenously administered labetalol in preeclamptic hypertensive emergencies. Study Design: Our study was a randomized, double-blind evaluation of nifedipine and labetalol in women with preeclampsia and a systolic blood pressure >170 mm Hg or a diastolic blood pressure >105 mm Hg. Nifedipine or labetalol and placebo were given, so patients received both tablet and intravenous solution. Hemodynamic parameters at dosing and at 15, 30, 60, and 120 minutes were recorded. Outcome measures were cardiac index, systemic vascular resistance index, mean arterial pressure, and heart rate. Data were analyzed by repeated-measures analysis of variance (Friedman test) with Dunn posttests, the Mann-Whitney U test, and the χ2 test with the Yates correction. Significance was set at P< .05. Results: At dosing, the nifedipine group (n = 6) had a cardiac index of 3.08 ± 0.51 L/min per square meter. There was a 43% increase in the cardiac index after nifedipine administration (P = .0008). There was no significant effect in the labetalol group (P = .697). There was a significant decrease in the systemic vascular resistance index after nifedipine dosing (P = .002) but no significant effect on this index after labetalol use (P = .479). The mean arterial pressure was significantly affected in both groups as follows: nifedipine, P = .001; labetalol, P = .004. The postanalysis showed significance at 60 minutes for both. An insignificant increase in heart rate with nifedipine (P = .147) and a significant decrease with labetalol (P = .034) were noted. Conclusions: Nifedipine increases cardiac index, whereas labetalol may not do so. (Am J Obstet Gynecol 1999;181:862-6.)