A randomised comparison of hydralazine and mini-bolus diazoxide for hypertensive emergencies in pregnancy: the PIVOT trial

Abstract

Aims: Diazoxide is one of few available agents for treatment of hypertensive emergencies in pregnancy. From previous studies, there is a question concerning safety after moderate-dose administration caused episodes of hypotension. Rapid control of severe hypertension is necessary to reduce maternal morbidity, for example, stroke and placental abruption. This study was designed to compare the efficacy of mini-bolus diazoxide with intravenous (i.v.) hydralazine.

Design: A randomised controlled trial.

Setting: Tertiary referral maternity hospital, Royal Prince Alfred Women and Babies, Sydney Australia.

Population: Antenatal and postnatal women with severe hypertension.

Methods: One hundred and twenty-four hypertensive women were randomised to either i.v. hydralazine (5 mg doses) or mini-bolus diazoxide (15 mg doses).

Primary outcome measure: Achievement of target blood pressure reduction; secondary measures included requirement for Caesarean section because of fetal deterioration as determined by non-reassuring cardiotocograph (CTG).

Results: Reduction in systolic and diastolic blood pressure was 34 min for hydralazine and 19 min for diazoxide (P < 0.001). There were no episodes of hypotension after diazoxide and one after hydralazine (after epidural). Episodes of persistent severe hypertension were more common with hydralazine (38%) than with diazoxide (16%), P < 0.01. The Caesarean section rate for no-reassuring CTG was no different between the two groups. Neonatal outcomes were similar.

Conclusion: Diazoxide and hydralazine are safe and effective antihypertensives, showing a controlled and comparable blood pressure reduction in women with hypertensive emergencies in pregnancy. The mini-bolus doses of 15 mg of diazoxide did not precipitate maternal hypotension as previously described and reduces episodes of persistent severe hypertension.