Hypertensive Emergency in Pregnancy

Hypertensive emergency in pregnancy is acute severe hypertension (systolic 160 mmHg or more or diastolic 110 mmHg or more, sustained for 15 minutes or more) with signs of acute end organ injury. Causes include severe preeclampsia, eclampsia, HELLP syndrome, chronic hypertension with kidney disease and, rarely, phaeochromocytoma. It matters because cerebral haemorrhage and heart failure can occur if blood pressure is not lowered within 30 to 60 minutes.

• Treat within 30 to 60 minutes of confirmation.
• Lower mean arterial pressure by no more than 25 percent in the first hour.
• Overly rapid lowering reduces uteroplacental blood flow.

Women have severe headache, visual disturbance, chest pain, breathlessness, confusion, seizure or reduced urine, with blood pressure at or above 160/110 mmHg. Some are asymptomatic but show organ injury on tests.

• Papilloedema and retinal haemorrhage in hypertensive encephalopathy.
• Pulmonary crackles in pulmonary oedema.
• Differential diagnosis: eclampsia, hypertensive encephalopathy, intracranial haemorrhage, aortic dissection, phaeochromocytoma, cocaine use, thyroid storm, renal artery stenosis, drug withdrawal.
• Complications: stroke, pulmonary oedema, heart failure, acute kidney injury, eclampsia, abruption, HELLP syndrome, fetal distress, maternal death.

The diagnosis is made by repeated severe readings with end organ injury.

• Blood pressure every 5 minutes with a correctly sized cuff, in the sitting or left lateral position.
• Full blood count, platelets, creatinine, urea, electrolytes, liver enzymes, lactate dehydrogenase, urine protein to creatinine ratio, glucose, coagulation screen.
• ECG, chest X-ray with shielding for pulmonary oedema, troponin if chest pain; CT or MRI of the brain for focal deficits or persistent coma.
• Ultrasound and cardiotocography; plasma metanephrines if blood pressure swings with palpitations and sweating.

The principle is a fast acting drug to bring blood pressure to 140 to 150/90 to 100 mmHg with magnesium sulphate when preeclampsia is present, then delivery or maintenance therapy.

• Supportive: admit to high dependency; left lateral position; oxygen if saturation is below 94 percent; two cannulae; urinary catheter with hourly output; total fluids 80 mL per hour; blood pressure every 5 minutes during titration, then every 15 minutes; continuous fetal monitoring.
• Pharmacological: labetalol 20 mg IV over 2 minutes then 40 mg, 80 mg and 80 mg at 10 minute intervals (maximum 220 mg), or labetalol infusion 1 to 2 mg per minute titrated (maximum 300 mg); or nifedipine immediate release 10 mg oral, repeated once after 30 minutes if needed; or hydralazine 5 mg IV over 1 to 2 minutes then 5 to 10 mg every 20 to 30 minutes (maximum 20 mg); magnesium sulphate 4 g IV over 20 minutes then 1 g per hour for 24 hours if preeclampsia or eclampsia is likely; furosemide 40 mg IV for pulmonary oedema; avoid sublingual nifedipine, sodium nitroprusside except as a last resort in intensive care, ACE inhibitors and angiotensin receptor blockers; maintenance with nifedipine modified release 30 to 60 mg oral once daily (maximum 120 mg) or methyldopa 250 to 500 mg oral 8-hourly (maximum 3 g daily); betamethasone 12 mg IM twice, 24 hours apart, before 34 weeks.
• Procedures: delivery after stabilisation for preeclampsia with severe features, eclampsia, HELLP syndrome, abruption or fetal compromise; induction with misoprostol 25 micrograms vaginal 6-hourly (maximum 4 doses) or Foley catheter with oxytocin, or caesarean section; intubation for coma or respiratory failure; phentolamine 1 to 5 mg IV bolus and alpha blockade for phaeochromocytoma, with surgery in the second trimester.
• Special groups: asthma uses nifedipine instead of labetalol; heart failure or pulmonary oedema needs furosemide and oxygen with nitroglycerin infusion 5 micrograms per minute increased every 3 to 5 minutes in intensive care; kidney disease reduces magnesium to 0.5 g per hour with level monitoring.
• Red flags: blood pressure still 160/110 mmHg or more after two drugs, seizure, chest pain, saturation below 94 percent, focal deficit, oliguria, fetal bradycardia.
• Follow-up: blood pressure every 15 minutes for 1 hour, then hourly for 4 hours, then 4-hourly; blood tests every 6 to 12 hours; postnatal blood pressure at 6 hours, daily for 5 days, then at 2 and 6 weeks.