Hypertensive Emergencies In Pregnancy Research Articles

Hypertension and hypertensive emergencies in pregnancy

Hypertensive emergencies are acute, life threatening, and usually--but not necessarily--associated with severe increases in blood pressure. In pregnancy, this is the fact in eclampsia. Eclampsia refers to the occurrence of one or more generalized convulsions in the setting of preeclampsia with proteinuria, edema, and hypertension. Our current understanding of the pathogenesis of preeclampsia will be reviewed here. Some major risk factors for the development are preexisting hypertension and renal disease. Preventive measures of preeclampsia and treatment of this specific hypertensive emergency in pregnancy are discussed.

▪ A Randomized, Double-Blind Trial of Oral Nifedipine and Intravenous Labetalol in Hypertensive Emergencies of Pregnancy

▪ A Randomized, Double-Blind Trial of Oral Nifedipine and Intravenous Labetalol in Hypertensive Emergencies of Pregnancy

A comparison between the haemodynamic effects of oral nifedipine and intravenous dihydralazine in patients with severe pre-eclampsia

To compare the effects of a single oral dose of nifedipine with those of intravenous dihydralazine on central haemodynamics in pregnant women with severe pre-eclampsia. A prospective comparative study. The High Risk Obstetric Unit, University Hospital Rotterdam Dijkzigt, Rotterdam. Twenty patients with severe pre-eclampsia between 27 and 35 weeks gestation with normal cardiac filling pressures and without fetal distress. A pulmonary artery thermodilution catheter and a radial artery line were placed. Ten patients chewed a 10-mg capsule of nifedipine and 10 patients received dihydralazine by intravenous infusion at a rate of 1-3 mg/h. Arterial pressures, heart rate, cardiac output and pulmonary capillary wedge pressure were determined before and after drug administration. Fetal condition was continuously monitored by cardiotocography. The reduction in arterial blood pressure obtained with both drugs was similar, and was associated with a similar rise in heart rate and cardiac output and a similar reduction in systemic vascular resistance. Pulmonary capillary wedge pressures decreased significantly less with nifedipine than with dihydralazine. Signs of fetal distress occurred in none of the nifedipine-treated patients, but in five of the patients treated with dihydralazine. From the haemodynamic viewpoint nifedipine seems to be a useful agent in the treatment of hypertensive emergencies in pregnancy.

Anticardiolipin Antibodies in Hypertensive Emergencies in Pregnancy

There are many similarities in the clinical conditions in women with antiphospholipld antibodies and pre-eclampsia. Both are associated with vascular thrombosis and low prostacyclin levels. Anticardiolipin antibody assays were performed in 33 black women with severe pre-eclampsia and compared with 32 normotensive women in the third trimester of pregnancy. No significant difference in anticardiolipin antibody levels were found between the groups. Thus, although women with elevated antiphospholid antibodies may be prone to pre-eclampsia, the converse may not be true.

Acute Hypertensive Crisis in Pregnancy

Severe pre-eclampsia is a state of acute afterload increase where compensation may be total by use of the Frank-Starling mechanism and/or increased adrenergic drive, or may be uncompensated in a patient with limited or exhausted preload reserve. As such, we are presented with a diverse group of patients and antihypertensive therapy ideally should be individualized. In reality we are dealing with a complex situation because of the presence of the fetus raising concerns about direct effects on the fetus as well as on uteroplacental blood flow. This limits our choice of agents to those with extensive use in pregnancy except in complicated or resistant cases. For these reasons, hydralazine is the antihypertensive agent of choice for treatment of acute hypertensive emergencies in pregnancy. In the complicated case other agents such as sodium nitroprusside or nitroglycerin may be more appropriate and, in these cases, hemodynamic monitoring should be performed to allow not only greater safety, but also to tailor therapy to the individual hemodynamic profile.

Labetalol does not decrease placental perfusion in the hypertensive term-pregnant rat

The acute effect of labetalol hydrochloride, a combined nonspecific beta-adrenergic and postsynaptic alpha 1-adrenergic blocker, on maternal hemodynamics and organ perfusion was investigated in 10 hypertensive, term-pregnant, spontaneously hypertensive rats with the use of the radioactive-labeled microsphere technique. The normal fall in blood pressure during pregnancy was prevented by the reduction of litter size to two conceptuses on day 7 of gestation. Labetalol (1 to 6 mg/kg) effectively lowered mean arterial pressure 22% by decreasing cardiac output 16%; total peripheral resistance was not significantly decreased. Thus, the blood pressure lowering effect of labetalol was due primarily to its beta-adrenergic blocking effect. Regional flows to the carcass and splanchnic circulation were decreased 19% and 15%, respectively, after labetalol administration. Uterine wall and ovarian perfusion were significantly reduced, but placental perfusion was not significantly altered. Because labetalol lowers blood pressure without reducing placental perfusion, it may be a useful alternative to hydralazine for the treatment of hypertensive emergencies in pregnancy.