ICU · cardiovascular

Acute hypertensive emergency — comprehensive ICU management (hypertensive encephalopathy, ICH, dissection, pre-eclampsia, phaeochromocytoma, cocaine)

Also known as Hypertensive emergency · Hypertensive crisis · Malignant hypertension · Hypertensive encephalopathy · Hypertensive urgency · Pre-eclampsia and eclampsia · Phaeochromocytoma crisis · Cocaine-induced hypertensive crisis · Cerebral autoregulation · PRES (posterior reversible encephalopathy syndrome) · INTERACT2 · STAT registry · Sublingual nifedipine (avoid)

Hypertensive emergency = a severe elevation of blood pressure (typically SBP 180 and/or DBP 120 mmHg) accompanied by ACUTE ongoing target-organ damage (cerebral — encephalopathy, intracerebral haemorrhage, ischaemic stroke; cardiac — acute coronary syndrome, acute pulmonary oedema, aortic dissection; renal — acute kidney injury with proteinuria/microangiopathy; retina — papilloedema and flame haemorrhages; pregnancy — pre-eclampsia/eclampsia). It is distinguished from hypertensive URGENCY (severe BP but NO acute end-organ damage), which is managed with ORAL agents over 24-48 h. The central pathophysiological principle is the cerebral autoregulation curve: in chronic hypertension the curve shifts to the RIGHT, so the brain depends on a higher mean arterial pressure (MAP) to maintain perfusion. Reducing BP too rapidly or to 'normal' values drops cerebral blood flow below the autoregulatory threshold and causes ISCHAEMIC stroke — hence the safe target for most emergencies is a 10-20% MAP reduction in the first hour, then gradual reduction to ~160/100 mmHg over 2-6 h. EXCEPTIONS requiring aggressive, immediate reduction are aortic dissection (SBP to 100-120 mmHg, beta-blocker FIRST to lower dP/dt) and ischaemic stroke pending thrombolysis decision. MANAGEMENT is in ICU/HDU with an arterial line and a titratable IV agent; drug selection is dictated by the SPECIFIC emergency: labetalol (alpha + beta-blocker, versatile, safe in pregnancy and post-stroke), nicardipine (smooth titratable calcium-channel blocker, the preferred agent for most), clevidipine (ultra-short-acting dihydropyridine), nitroglycerin (ACS and pulmonary oedema), esmolol (aortic dissection — titratable beta-blockade), hydralazine (pregnancy), phentolamine (phaeochromocytoma — alpha-blockade), and fenoldopam (renal-protective). AVOID sodium nitroprusside where possible (cyanide/thiocyanate toxicity, increases intracranial pressure, coronary steal) and NEVER give sublingual nifedipine (unpredictable precipitous fall - stroke/MI). SPECIAL CASES: intracerebral haemorrhage - lower SBP to 140 mmHg (INTERACT2 — intensive lowering to 140 improved functional outcome); pre-eclampsia/eclampsia - MAGNESIUM SULPHATE FIRST for seizure prevention/treatment, then labetalol/hydralazine; phaeochromocytoma - ALPHA-blockade (phentolamine/phenoxybenzamine) BEFORE any beta-blocker (unopposed alpha-1 stimulation - catastrophic hypertension); cocaine-induced - BENZODIAZEPINES first (calm sympathetic surge), avoid pure beta-blockers (unopposed alpha).