Hypertensive Emergency Pharmacotherapy

Hypertensive emergency is severe blood pressure elevation, usually over 180/120 mm Hg, with acute target organ damage (encephalopathy, stroke, acute heart failure, aortic dissection, acute kidney injury, eclampsia). It is treated with intravenous drugs in a monitored setting, and the pressure is lowered in a controlled way.

Usual target. Lower mean arterial pressure by no more than 25 percent in the first hour, then to about 160/100 mm Hg over 2 to 6 hours, and then to normal over 24 to 48 hours.

Exceptions.

• Aortic dissection: systolic pressure under 120 mm Hg and heart rate under 60 within 20 minutes.

• Ischaemic stroke: lower only if over 220/120 mm Hg (185/110 before thrombolysis).

• Intracerebral haemorrhage: systolic pressure of 140 to 160 mm Hg.

• Pre-eclampsia and eclampsia: under 160/110 mm Hg.

Choice by condition.

• Most emergencies: labetalol or nicardipine.

• Acute pulmonary oedema or ischaemia: glyceryl trinitrate.

• Aortic dissection: esmolol or labetalol, with an added vasodilator.

• Catecholamine excess (phaeochromocytoma): phentolamine.

• Pregnancy: labetalol, hydralazine or oral nifedipine, with magnesium sulphate for eclampsia.

• Sodium nitroprusside: last resort, with arterial monitoring.

Avoid. Sublingual or short-acting nifedipine in non-pregnant adults, and labetalol in asthma, heart block, bradycardia and acute heart failure.

Special groups.

• Children: specialist dosing.

• Kidney failure: avoid prolonged nitroprusside, because of thiocyanate.

• East Africa: eclampsia and hypertensive heart failure are common. Where infusion pumps are unavailable, use intermittent intravenous labetalol or hydralazine boluses, with blood pressure checks every 5 to 15 minutes.

• Labetalol: 20 mg intravenously over 2 minutes, then 40 to 80 mg every 10 minutes to a maximum of 300 mg, or infusion 0.5 to 2 mg/min.

• Nicardipine: 5 mg/h, increased by 2.5 mg/h every 5 to 15 minutes to a maximum of 15 mg/h.

• Glyceryl trinitrate: 5 to 200 micrograms/min.

• Esmolol: 500 micrograms/kg bolus, then 50 to 300 micrograms/kg/min.

• Hydralazine: 5 to 10 mg intravenously, repeated after 20 minutes.

• Phentolamine: 1 to 5 mg intravenously.

• Sodium nitroprusside: 0.3 to 0.5 micrograms/kg/min, up to 10 micrograms/kg/min for a short time, protected from light.

• Nifedipine (pregnancy): 10 mg immediate release orally, repeated every 20 minutes.

• Magnesium sulphate (eclampsia): 4 g intravenously over 5 to 15 minutes, then 1 g/h for 24 hours.

Monitoring. Arterial line for infusions, blood pressure every 5 to 15 minutes, neurological checks, urine output, ECG, and renal function.

Stop rules. Stop the infusion at target and convert to oral therapy. Reduce for hypotension or neurological worsening.

Referral and escalation. Seek intensive care for infusions, and cardiothoracic or vascular review for aortic dissection. Seek obstetric support for pregnancy.

Common errors. Lowering the pressure too fast, using short-acting nifedipine, treating hypertension without target organ damage as an emergency, and omitting magnesium in eclampsia.