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Hypertensive emergency
What turns very high blood pressure into an emergency is acute target-organ damage — not the number itself; in an emergency pressure is lowered gradually with an intravenous infusion, and without organ damage it is lowered slowly with tablets.
Why it matters in the exam
The central question is the distinction between a hypertensive emergency and very high blood pressure without acute damage (hypertensive urgency). In an emergency there is acute damage: encephalopathy, malignant hypertension with retinal changes, pulmonary oedema, an acute coronary syndrome, dissection, severe pre-eclampsia or eclampsia, a phaeochromocytoma crisis, acute kidney injury or intracerebral haemorrhage. Without such damage — oral treatment and gradual lowering over 24–48 hours.
Questions also test the rate of lowering: in most situations a fall of up to 25% in mean arterial pressure over the first hours, and not rapid normalisation, which can cause cerebral ischaemia. The exceptions need fast lowering: dissection (systolic below 120 and heart rate below 60), pulmonary oedema and acute coronary syndrome (systolic below 140). In ischaemic stroke pressure is lowered only above 220/120, or to below 185/110 before thrombolysis.
The right drug for each situation is also asked: nitroglycerin for pulmonary oedema and ischaemia, a beta-blocker first in dissection, an alpha-blocker (phentolamine) before any beta-blocker in phaeochromocytoma, benzodiazepines for cocaine, magnesium with labetalol or nifedipine in eclampsia, and an ACE inhibitor in scleroderma renal crisis.
Key points
- Emergency = very high blood pressure with acute target-organ damage; without damage — oral treatment.
- In most cases: lower mean pressure by up to 25% over the first hours.
- Exceptions: dissection (systolic below 120, rate below 60), pulmonary oedema and coronary syndrome (below 140).
- Ischaemic stroke: lower only above 220/120, or to below 185/110 before thrombolysis.
- Drug by situation: nitroglycerin, beta-blocker in dissection, phentolamine in phaeochromocytoma, magnesium in eclampsia.
Summary table
| Situation | Target | Preferred drug | Note |
|---|---|---|---|
| Most emergencies | Lower mean pressure by up to 25% over the first hours, then gradually | Labetalol or nicardipine infusion | Do not normalise quickly |
| Aortic dissection | Systolic below 120 and heart rate below 60, fast | Esmolol or labetalol, then a vasodilator | Beta-blocker before vasodilator |
| Pulmonary oedema, acute coronary syndrome | Systolic below 140 | Nitroglycerin (and a diuretic in oedema) | — |
| Ischaemic stroke | Lower only above 220/120; before thrombolysis below 185/110 | Labetalol or nicardipine | Sharp lowering harms the threatened brain |
| Eclampsia or severe pre-eclampsia | Systolic below 160 and diastolic below 105 | Labetalol, nifedipine or hydralazine, with magnesium sulfate | ACE inhibitors forbidden |
| Phaeochromocytoma, cocaine | Safe lowering | Phentolamine; benzodiazepines for cocaine | No beta-blocker on its own |
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Sources
- ESC Guidelines for the management of elevated blood pressure and hypertension, 2024 — Hypertensive emergencies
- ESC Council on Hypertension position document on the management of hypertensive emergencies, 2019 — Treatment targets by type of organ damage
- Harrison's Principles of Internal Medicine, 21st edition (2022) — Hypertensive Emergencies
Sources are given for further reading; the text is written afresh and not copied from them.
Reviewed by the Examqo AI Professor · 2026-11-02. The text may contain errors; when in doubt, check the source.