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 adm inistered nifedipine and intravenously administered labetatol in preeclampt ic hypertensive emergencies. STUDY DESIGN: Our study was a randomized, double-blind evaluation of nifedi pine and labetalol in women with preeclampsia and a systolic blood pressure >170 mm Hg or a diastolic blood pressure >105 mm Hg. Nifedipine or labetal ol and placebo were given, so patients received both tablet and intravenous solution. Hemodynamic parameters at dosing and at 15, 30, 60, and 120 minu tes were recorded. Outcome measures were cardiac index, systemic vascular r esistance index, mean arterial pressure, and heart rate. Data were analyzed by repeated-measures analysis of variance (Friedman test) with Dunn postte sts, the Mann-Whitney U test, and the chi(2) 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 in dex after nifedipine administration (P=.0008). There was no significant eff ect in the labetalol group (P=.697). There was a significant decrease in th e systemic vascular resistance index after nifedipine dosing (P=.002) but n o significant effect on this index after labetalol use (P=.479). The mean a rterial pressure was significantly affected in both groups as follows: nife dipine, P=.001; labetalol, P=.004. The postanalysis showed significance at 60 minutes for both. An insignificant increase in heart rate with nifedipin e (P=.147) and a significant decrease with labetalol (P=.034) were noted. CONCLUSIONS: Nifedipine increases cardiac index, whereas labetalol may not do so.