Hypertensive Crisis
Definition
Hypertensive crisis is severe blood-pressure elevation divided by whether target-organ damage is occurring. Hypertensive emergency is blood pressure above 180/120 mmHg with new or worsening target-organ damage; hypertensive urgency is severe elevation in a stable patient with no acute or impending organ damage. The number itself does not distinguish them — the organ does.
Key Concepts
Emergency — the rate of reduction is the treatment
- With a compelling condition — aortic dissection, severe pre-eclampsia or eclampsia, phaeochromocytoma crisis — reduce systolic pressure to <140 mmHg within the first hour, and to <120 mmHg in aortic dissection.
- Without a compelling condition, reduce systolic pressure by no more than 25% in the first hour, then to 160/100 mmHg over the next 2–6 hours, then cautiously towards normal over 24–48 hours.
- Admit to ICU or CCU with continuous blood-pressure monitoring.
- (sources/Handbook-HA-2024, rating: high)
Intravenous agents for hypertensive emergency
| Agent | Dose | Notes |
|---|---|---|
| Labetalol | 20 mg IV, then 20–80 mg every 10 min to a maximum of 300 mg; then 0.5–2 mg/min (up to 10 mg/min) | First line for most emergencies; avoid in acute LV failure |
| Sodium nitroprusside | 0.25–0.5 µg/kg/min, increasing by 0.5 µg/kg/min every 5 min to a maximum of 10 µg/kg/min | Limit to <3 µg/kg/min if eGFR <30; protect from light and discard after 12 h; avoid in pregnancy and beyond 48 h |
| Hydralazine | 10–20 mg slow IV over 20 min, repeat 4–6-hourly | Unpredictable and prolonged effect; not first line; avoid in AMI and dissection |
| Phentolamine | 5–10 mg IV, repeat every 10–20 min | Catecholamine crisis |
(Table: sources/Handbook-HA-2024)
Condition-specific choices
| Condition | Prefer | Avoid |
|---|---|---|
| Acute pulmonary oedema | Nitroprusside or GTN plus a loop diuretic | Diazoxide, hydralazine; labetalol and β-blockers in LV dysfunction |
| Angina or acute MI | Nitroglycerin, nitroprusside, labetalol, calcium channel blocker | Diazoxide, hydralazine |
| Sympathomimetic excess, clonidine withdrawal, phaeochromocytoma | Phentolamine, labetalol, nitroprusside | β-blockers — unopposed α-vasoconstriction raises pressure further |
| Aortic dissection | Nitroprusside plus labetalol or propranolol | Any vasodilator before rate control; hydralazine, diazoxide |
| Pregnancy | IV hydralazine, nicardipine, labetalol | Nitroprusside (cyanide toxicity), ACE inhibitors |
(Table: sources/Handbook-HA-2024)
Urgency
- No acute organ damage. Most such patients have withdrawn from or are non-compliant with antihypertensive therapy.
- Treatment is reinstitution or intensification of oral therapy — not intravenous drugs, which risk precisely the over-rapid reduction the emergency protocol is built to avoid.
- Look for secondary causes, such as renal artery stenosis.
Contradictions / Open Questions
- The 180/120 threshold is a convention, not a measurement-derived cut-off. The handbook adopts it without discussion, and every recommendation downstream inherits the arbitrariness. A patient at 175/115 with hypertensive encephalopathy is an emergency by mechanism yet misses the definition. (sources/Handbook-HA-2024, rating: high)
- The "25% in the first hour" rule is physiology, not trial evidence. It rests on the argument that cerebral autoregulation has shifted rightwards in chronic hypertension, so a normal pressure reached quickly is a hypotensive pressure to that patient's brain. The handbook gives the rule without the reasoning and without a citation, and the wiki holds no source testing it.
- The compelling-condition list is shorter than the conditions that behave compellingly. Dissection, eclampsia and phaeochromocytoma crisis are named. Acute ischaemic stroke, intracerebral haemorrhage and acute coronary syndrome are excluded — the handbook says the first two are "not discussed here" — leaving the reader to infer their targets from other sources the page does not link.
- Hydralazine is listed despite being described as unsuitable for first line. It appears in the agent table for hypertensive emergency and again in the pregnancy row, while the note says its unpredictable and prolonged effect makes it a poor first choice. The page therefore recommends and discourages the same drug without saying which patient gets it.
- β-blockade is contraindicated and preferred for the same pressure depending on mechanism. Labetalol is first-line for most emergencies and is the agent named for the sympathetic-crisis and dissection rows, yet β-blockers are prohibited in sympathomimetic crisis and in acute LV failure. The rule is not "avoid β-blockers" or "use them" but an unreconciled dependence on the mechanism, which the agent table alone does not make safe.
- The wiki's hypertension page covers none of this. entities/Hypertension is built on newer ESC and AHA material and contains no crisis, emergency or urgency content at all, so there is nothing to check these targets against and nothing recording whether the newer guidelines moved them.
Connections
- Related to entities/Hypertension — the chronic condition this complicates, and the page that should carry the diagnostic thresholds
- Related to concepts/Acute-Aortic-Syndrome — the one emergency whose targets override the 25% rule
- Related to concepts/Decompensated-HF-Management — flash oedema is the commonest cardiac presentation of hypertensive emergency
- Related to concepts/Hypertensive-Disorders-of-Pregnancy — eclampsia is a compelling indication and has its own drug restrictions
- Related to concepts/Cardiogenic-Shock — the failure mode of over-treatment, and the reason for the rate limit
- Related to entities/Acute-Coronary-Syndrome — a target-organ consequence, and a condition where hydralazine and diazoxide are contraindicated
- Related to entities/Atrial-Fibrillation — uncontrolled rate is a reversible precipitant rather than a pressure problem