Objective To audit the use of bolus hydralazine for control of severe hypertension within a protocol for the management of severe pre-eclampsia.

Design A retrospective review.

Setting Three UK teaching hospitals.

Subjects Seventy consecutive women who received hydralazine for the treatment of sustained severe hypertension. Twenty-five women had more than one episode of hypertension amounting to a total of 109 treatment episodes.

Intervention Intravenous bolus hydralazine 5 mg, repeated every 15min to reduce the mean arterial pressure to < 125 mmHg.

Main outcome measures Change in mean arterial pressure in response to bolus hydralazine, fetal condition, as assessed by heart rate changes and umbilical arterial pH at delivery, and protocol violations were analysed.

Results Mean arterial pressure fell by 12 mmHg (95% CI 10–14) after the first bolus, 9 mmHg (95% CI 6.5–12) after the second bolus and 5 mmHg (95% CI 1–10) after the third bolus. Eighty-two (75 %) episodes were managed strictly according to the protocol; of these, blood pressure was controlled by bolus therapy alone in 89%. Of the 27 instances in which the protocol was not adhered to, blood pressure was not controlled in four. There were no significant differences in the incidence of cardiotocographic abnormalities or umbilical acidaemia in the women treated before delivery (n= 36) compared with those in whom treatment was first initiated afterwards (n= 34).

Conclusions Hydralazine given in 5 mg boluses is a safe and effective method of treating severe hypertension in pre-eclampsia. Despite clear management guidelines, protocol violations were common, and in 4% of treatment episodes these were potentially serious resulting in failure to control blood pressure.