Hypertensive emergencies include both accelerated hypertension and malignant hypertension. In both cases a recent increase in blood pressure to very high levels (≥180 mm Hg systolic and ≥110 mm Hg diastolic) results in target organ damage (usually seen as neurological (eg encephalopathy), cardiovascular or renal damage). The term malignant hypertension is usually reserved for cases where papilloedema is present.
Where there is no evidence of target organ damage, the condition is a hypertensive "urgency" rather than "emergency", and treatment may be more gradual.
Finding accelerated hypertension or malignant hypertension in a patient demands urgent admission for assessment and treatment to lower blood pressure within hours in order to minimise further end-organ damage and reduce the risk of life-threatening events such as myocardial infarction (MI), encephalopathy and intracerebral or subarachnoid haemorrhage. The National Institute for Health and Clinical Excellence (NICE) recommends same day referral for accelerated hypertension with papilloedema and/or retinal haemorrhages, or for patients suspected of having a phaeochromocytoma (labile or postural hypotension, headache, palpitations, pallor and sweating.
Accelerated hypertension may be seen in association with renal disease or may occur as a discrete entity and will occur in approximately 1% of patients with essential hypertension. Average age at presentation is 40 years. Men are more commonly affected than women.
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- Unilateral renovascular hypertension, e.g renal artery stenosis.
- Renin-secreting neoplasms.
- Trauma to the kidneys.
- Renal vasculitis, eg scleroderma, polyarteritis and systemic lupus erythematosus.
- Cocaine abuse.
- Drugs such as monoamine-oxidase inhibitors, combined oral contraceptives or the withdrawal of alcohol, alpha stimulants such as clonidine, or beta-blockers.
- Sodium-volume overload and low renin levels, eg acute glomerulonephritis, primary aldosteronism.
- Hyperthyroidism or hypothyroidism.
This may be asymptomatic or may present with any of the many symptoms and/or signs of end-organ damage:
- Nausea and vomiting.
- Visual disturbance.
- Chest pain.
- Neurological deficit, eg cerebrovascular event (CVE).
- Bleeding due to disseminated intravascular coagulopathy (DIC).
- Microangiopathic haemolytic anaemia.
The investigation of any patient thought to have accelerated hypertension should be undertaken urgently and by doctors with expertise in this field. Investigations should include:
- Full history - including:
- Past medical history.
- Full systems review.
- Drug history including over-the-counter, herbal remedies and recreational drugs.
- Full examination - including:
- Blood pressure measurements - lying, standing and in both arms (looking for coarctation or aortic dissection).
- Fundoscopy - retinopathy, eg grade III (flame haemorrhages, dot and blot haemorrhages, hard and soft exudates) to grade IV (papilloedema).
- Cardiovascular examination - lying and standing blood pressure; look for signs of cardiac failure or pulmonary oedema, carotid or renal bruits, left ventricular heave, cardiac murmurs, third or fourth heart sounds.
- Neurological examination.
- Blood tests:
- FBC ± clotting screen.
- U&Es, creatinine.
- Liver and TFTs.
- Blood sugar measurement.
- ± Cardiac enzymes and fasting blood lipids.
- ± Ambulatory blood pressure monitoring.
- Urine dip testing for protein and blood.
- CXR - cardiac size, cardiac failure, etc.
- ECG - left ventricular hypertrophy or left atrial enlargement.
Subsequent investigations may include:
- CT/MRI scan of the head or kidneys.
- Plasma renin activity.
- Plasma aldosterone level.
- 24-hour urine for vanillylmandelic acid (VMA) and catecholamine levels.
- Auto-antibody levels, eg antinuclear factor.
The aim is to reduce the blood pressure over 24-48 hours. Patients usually have altered blood pressure autoregulation and if the blood pressure is reduced too fast, there may be organ hypoperfusion.
- Initially, try to reduce the mean arterial pressure by approximately 25% over the first 24-48 hours.
- An arterial line is helpful for continuous blood pressure monitoring.
- There may be severe sodium and volume depletion; volume expansion with isotonic sodium chloride solution may be required.
Initially, an intravenous (IV) route is usually used. Nitroprusside is the most commonly used IV drug. Labetolol or nicardipine are alternatives which can be switched to oral formulations once blood pressure control is achieved.
Phentolamine is the drug of choice for a phaeochromocytoma crisis.
Also available parenterally are diltiazem, verapamil and enalapril. Hydralazine is reserved for use in pregnant patients.
Without treatment, accelerated hypertension may result in death within a year in over 90% of patients as a result of end-organ damage, eg MI, CVE or renal failure. The prognosis has improved dramatically over the last few decades and with optimal treatment the five-year survival rate is >80%.
Further reading & references
- Bisognano JD, Hypertensive Emergencies, Medscape, Sep 2011
- Hypertension: management of hypertension in adults in primary care, NICE Clinical Guideline (August 2011)
- Blumenfeld JD, Laragh JH; Management of hypertensive crises: the scientific basis for treatment decisions. Am J Hypertens. 2001 Nov;14(11 Pt 1):1154-67.
- Williams B, Poulter NR, Brown MJ, et al; British Hypertension Society guidelines for hypertension management 2004 (BHS-IV): summary. BMJ. 2004 Mar 13;328(7440):634-40.
|Original Author: Dr Huw Thomas||Current Version: Dr Huw Thomas||Peer Reviewer: Dr Hannah Gronow|
|Last Checked: 17/11/2011||Document ID: 1746 Version: 22||© EMIS|
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