Hypertensive crisis

Hypertensive crisis is a severe elevation of blood pressure, systolic 180 mmHg or more or diastolic 120 mmHg or more, and divides into two entities by whether acute target organ damage is present.

Hypertensive emergency is severe hypertension with new or progressing damage to the brain, heart, aorta, kidneys, eyes or placenta, and needs immediate controlled reduction with intravenous drugs in a monitored setting.

Hypertensive urgency is severe hypertension without acute organ damage; it needs gradual reduction with oral drugs over hours to days and is not an emergency.

Clinical relevance. Hypertensive crisis accounts for 2% to 3% of emergency visits, and about 25% of these are true emergencies. Without treatment a hypertensive emergency carries a high one year mortality. The danger lies in missing organ damage, and equally in lowering pressure too fast or too far, which causes stroke, coronary and renal ischaemia and blindness.

Classification of hypertensive emergencies.

• Neurological: hypertensive encephalopathy, acute ischaemic stroke, intracerebral haemorrhage, subarachnoid haemorrhage, posterior reversible encephalopathy syndrome.
• Cardiac: acute pulmonary oedema (acute heart failure), acute coronary syndrome, acute aortic dissection.
• Renal: malignant (accelerated) hypertension with acute kidney injury, scleroderma renal crisis, thrombotic microangiopathy.
• Retinal: retinal haemorrhages, exudates and papilloedema.
• Obstetric: severe pre-eclampsia, eclampsia, HELLP syndrome (haemolysis, elevated liver enzymes, low platelets).
• Catecholamine and drug related: phaeochromocytoma crisis, sympathomimetic toxicity (cocaine, amphetamines), monoamine oxidase inhibitor interaction with tyramine or sympathomimetics, clonidine or beta blocker withdrawal, autonomic dysreflexia.
• Perioperative: postoperative severe hypertension.

Mechanism. Failure of cerebral and renal autoregulation, with endothelial injury, fibrinoid necrosis of arterioles, loss of natriuresis, and activation of the renin angiotensin system, produces a vicious circle of rising pressure and organ injury. Chronic hypertension shifts the autoregulation curve to the right, so organ perfusion falls if pressure is lowered too far or too fast.

History.

• Symptoms: headache, visual blurring or loss, confusion, drowsiness, seizures, focal weakness, speech disturbance, chest pain, tearing pain radiating to the back, breathlessness, orthopnoea, nausea and vomiting, reduced urine, haematuria, epistaxis, palpitations, sweating.
• Known hypertension, previous readings, adherence, recent missed doses or sudden withdrawal of clonidine or beta blockers.
• Drugs and substances: cocaine, amphetamines, ecstasy, MDMA, ephedrine and decongestants, monoamine oxidase inhibitors with tyramine rich food (aged cheese, cured meat), NSAIDs, steroids, ciclosporin, tacrolimus, erythropoietin, VEGF inhibitors, liquorice, alcohol withdrawal.
• Pregnancy, postpartum status, gestational age (over 20 weeks), headache and right upper quadrant pain.
• Spinal cord injury (autonomic dysreflexia), recent surgery, scleroderma, kidney disease, previous aortic disease or Marfan syndrome.

Examination.

• Blood pressure in both arms (difference over 20 mmHg suggests dissection), heart rate, temperature, saturation; repeat after rest in a quiet room (an initial high reading from pain or anxiety may fall).
• Fundoscopy: haemorrhages, cotton wool spots, hard exudates, papilloedema (grade III to IV retinopathy defines malignant hypertension).
• Neurological: consciousness, focal deficit, meningism, visual fields, gait, reflexes, clonus, papilloedema.
• Cardiac and respiratory: gallop rhythm, new murmur (aortic regurgitation), pulse deficit, crackles, raised jugular venous pressure.
• Abdomen: bruit, pulsatile mass, distended bladder. Pulses: unequal or absent.
• Obstetric: fundal height, oedema, hyperreflexia, clonus, right upper quadrant tenderness.

Red flags (signs of acute organ damage).

• Encephalopathy: severe headache, vomiting, confusion, drowsiness, convulsions, cortical blindness.
• Focal neurological deficit, meningism or reduced consciousness.
• Chest pain with ischaemic ECG changes, or tearing pain with pulse or pressure asymmetry or a new diastolic murmur.
• Pulmonary oedema.
• Fundal haemorrhages, exudates or papilloedema.
• Oliguria, haematuria, rising creatinine, microangiopathic haemolysis (schistocytes).
• Pregnancy over 20 weeks, or within 6 weeks after delivery, with pressure of 160/110 mmHg or more, proteinuria, visual disturbance or epigastric pain.

Hypertensive emergency (organ damage present). Hypertensive encephalopathy, malignant hypertension, acute aortic dissection, acute pulmonary oedema, acute myocardial infarction, intracerebral or subarachnoid haemorrhage, ischaemic stroke, eclampsia and severe pre-eclampsia, HELLP syndrome, phaeochromocytoma crisis, scleroderma renal crisis, sympathomimetic toxicity, thrombotic microangiopathy.

Hypertensive urgency or severe asymptomatic hypertension. Poorly controlled chronic hypertension, non adherence, drug withdrawal, NSAIDs or steroids, high salt, pain, anxiety, alcohol use, urinary retention, sleep apnoea, white coat effect.

Conditions that raise pressure secondarily and mimic a crisis. Pain (renal colic, fracture), anxiety and panic attack, acute alcohol or benzodiazepine withdrawal, hypoxia and hypercapnia, raised intracranial pressure (Cushing reflex with bradycardia), full bladder, autonomic dysreflexia, thyroid storm.

Mimics of organ damage. Migraine, stroke mimics (hypoglycaemia, seizure), acute coronary syndrome presenting with pain from reflux, hyperventilation.

1. Confirm with repeated measurement after rest, correct cuff and both arms; look for features of organ damage and any trigger within the first 10 minutes.
2. All patients: 12 lead ECG (ischaemia, left ventricular hypertrophy, arrhythmia), troponin, urea, creatinine, electrolytes, glucose, full blood count and blood film (schistocytes), urinalysis for protein, blood and casts, urine albumin or protein to creatinine ratio, pregnancy test in women of childbearing age.
3. Suspected hypertensive emergency: lactate dehydrogenase, haptoglobin, bilirubin, coagulation screen, liver function tests, creatine kinase, natriuretic peptide, arterial or venous gas; chest radiograph; urine toxicology screen when drug use is suspected.
4. Neurological symptoms: CT head without contrast at once (haemorrhage, infarct, oedema), then MRI (posterior reversible encephalopathy syndrome shows posterior white matter oedema); CT angiography for subarachnoid haemorrhage; lumbar puncture only if CT is normal and subarachnoid haemorrhage remains likely.
5. Chest pain or back pain: CT aortography (or transoesophageal echocardiography) for dissection; echocardiography for ventricular function, pericardial effusion and aortic root; coronary angiography as indicated.
6. Kidney: renal ultrasound; kidney biopsy in selected cases; serology (antinuclear antibody, complement, anti glomerular basement membrane) if glomerulonephritis is suspected.
7. Secondary cause work up once stable: plasma free metanephrines, aldosterone to renin ratio, thyroid function, renal artery imaging.
8. Pre-eclampsia: urine protein to creatinine ratio (over 30 mg/mmol), liver enzymes, platelets, uric acid, lactate dehydrogenase, foetal assessment by cardiotocography and ultrasound.
9. Fundoscopy by a clinician or retinal photography.

Limits. A single high reading is not a crisis; the diagnosis rests on organ damage, not the number. Blood pressure may be only modestly raised in pre-eclampsia with eclampsia, and in acute kidney injury from scleroderma. Troponin may rise from severe hypertension alone (type 2 injury).

General principles for hypertensive emergency. Admit to a monitored high dependency or intensive care bed; secure an intravenous line; continuous ECG, oxygen saturation and, in most cases, an arterial line; urinary catheter for hourly output; treat with titratable intravenous drugs; treat the cause; avoid hypotension and abrupt falls.

Unless a specific condition sets a different target, lower mean arterial pressure by no more than 20% to 25% within the first hour, then to about 160/100 mmHg over the next 2 to 6 hours, then cautiously towards normal over 24 to 48 hours. Stop immediately if neurological, cardiac or renal function worsens. Intravenous drugs.

• Labetalol: 20 mg intravenously over 2 minutes, then 20 to 80 mg every 10 minutes (cumulative maximum 300 mg), or infusion 0.5 to 2 mg/minute; avoid in acute heart failure, asthma, bradycardia and high degree heart block, and in cocaine toxicity without alpha blockade.
• Nicardipine: 5 mg/hour, increased by 2.5 mg/hour every 5 to 15 minutes to a maximum of 15 mg/hour; useful in stroke, encephalopathy and perioperative states; avoid in acute heart failure and advanced aortic stenosis.
• Clevidipine (where available): 1 to 2 mg/hour, doubling every 90 seconds initially to 4 to 6 mg/hour; maximum 16 mg/hour.
• Glyceryl trinitrate: 5 micrograms/minute increasing by 5 micrograms/minute every 3 to 5 minutes to a maximum of 200 micrograms/minute; preferred in pulmonary oedema and acute coronary syndrome; avoid with phosphodiesterase 5 inhibitor use in the previous 24 to 48 hours.
• Sodium nitroprusside: 0.25 to 0.5 micrograms/kg/minute increasing every 2 to 3 minutes to a usual maximum of 10 micrograms/kg/minute.
• Nitroprusside cautions (use over 2 micrograms/kg/minute for only a few minutes to limit cyanide and thiocyanate toxicity; infusions over 24 to 48 hours or in kidney or liver failure need level monitoring; shield from light); an arterial line is essential; avoid in pregnancy except as a last resort and in raised intracranial pressure.
• Esmolol: 500 micrograms/kg bolus over 1 minute, then 50 micrograms/kg/minute increased by 50 micrograms/kg/minute every 4 minutes to a maximum of 300 micrograms/kg/minute; used in dissection and perioperative hypertension.
• Hydralazine: 5 to 10 mg intravenously slowly every 20 to 30 minutes (maximum 20 mg); mainly used in eclampsia; unpredictable response, reflex tachycardia.
• Phentolamine: 1 to 5 mg intravenous bolus, repeated every 5 to 15 minutes, or infusion 0.1 to 2 mg/minute, for catecholamine excess (phaeochromocytoma, clonidine withdrawal, monoamine oxidase inhibitor reactions).
• Fenoldopam (where available) 0.1 to 1.6 micrograms/kg/minute and urapidil 12.5 to 25 mg bolus then 5 to 40 mg/hour (where available).
• Furosemide: 40 to 80 mg intravenously with a vasodilator in pulmonary oedema or volume overload (not for volume depleted patients).
• Enalaprilat 0.625 to 1.25 mg intravenously over 5 minutes every 6 hours is avoided in acute myocardial infarction and bilateral renal artery stenosis.

Condition specific management.

• Hypertensive encephalopathy and malignant hypertension: labetalol or nicardipine; reduce mean arterial pressure by 20% to 25% in the first hour; benzodiazepine for seizures (lorazepam 4 mg intravenously, repeat once after 10 minutes); avoid precipitous falls in kidney disease.
• Acute aortic dissection: reduce heart rate to under 60 beats/minute with esmolol (or labetalol) first, then systolic pressure to 100 to 120 mmHg within 20 minutes, adding nicardipine or nitroprusside after beta blockade.
• Opioid analgesia (morphine 2.5 to 5 mg intravenously).
• Emergency surgery for type A; medical management with endovascular repair for complicated type B.
• Acute pulmonary oedema: sit upright, oxygen to keep saturation 94% to 98%, glyceryl trinitrate infusion, furosemide 40 to 80 mg intravenously, continuous positive airway pressure 5 to 10 cmH2O; avoid beta blockers acutely.
• Acute coronary syndrome: glyceryl trinitrate, beta blocker (metoprolol 25 mg orally or esmolol; avoid in heart failure or shock), antiplatelet therapy and anticoagulation, and early reperfusion.
• Acute ischaemic stroke: do not lower pressure unless it exceeds 220/120 mmHg (then reduce by about 15% in 24 hours).
• Before thrombolysis, lower to under 185/110 mmHg and keep under 180/105 mmHg for 24 hours afterwards (labetalol 10 to 20 mg intravenously or nicardipine infusion).
• Intracerebral haemorrhage: lower systolic pressure promptly to about 130 to 140 mmHg (avoid under 130) with labetalol or nicardipine, within 1 hour of presentation if systolic is 150 to 220 mmHg.
• Subarachnoid haemorrhage: maintain systolic pressure under 160 mmHg until the aneurysm is secured, with nimodipine 60 mg orally every 4 hours for 21 days.
• Severe pre-eclampsia and eclampsia: lower pressure to under 160/110 mmHg promptly, ideally 140 to 150/90 to 100 mmHg, with labetalol 20 mg intravenously then 40 mg, 80 mg and 80 mg every 10 minutes (maximum 220 mg).
• Alternatively, nifedipine immediate release 10 mg orally repeated after 20 to 30 minutes (maximum 30 mg in the first hour in some regimens).
• Or hydralazine 5 mg intravenously.
• Magnesium sulphate 4 g intravenously over 5 to 15 minutes then 1 g/hour for 24 hours (monitor reflexes, respiratory rate and urine output; calcium gluconate 1 g intravenously for toxicity).
• Expedite delivery after maternal stabilisation. Avoid ACE inhibitors, angiotensin receptor blockers and nitroprusside.
• Phaeochromocytoma crisis: phentolamine 5 mg intravenously then infusion, or nicardipine; beta blocker only after alpha blockade; surgery after preparation.
• Sympathomimetic toxicity (cocaine, amphetamines): benzodiazepines first (diazepam 5 to 10 mg intravenously repeated every 5 to 10 minutes), then phentolamine, nicardipine or glyceryl trinitrate; avoid pure beta blockers.
• Clonidine or beta blocker withdrawal: restart the drug; add phentolamine or nitroprusside if needed.
• Scleroderma renal crisis: start captopril 6.25 to 12.5 mg orally and increase every 6 to 12 hours to 50 mg three times daily, aiming to reduce pressure by 10 to 20 mmHg a day; do not use steroids; dialysis support if needed.
• Autonomic dysreflexia: sit upright, loosen clothing, relieve bladder or bowel distension (catheter), check for skin and other triggers, nifedipine 10 mg orally or glyceryl trinitrate 400 micrograms sublingually if pressure remains over 150 mmHg systolic.
• Perioperative hypertension: treat pain, then labetalol, nicardipine or esmolol.

Hypertensive urgency (no organ damage). No admission is usually needed if reliable follow up is available.

Restart or intensify oral drugs, for example amlodipine 5 to 10 mg daily, an ACE inhibitor (ramipril 2.5 to 5 mg or captopril 12.5 to 25 mg) or a thiazide like diuretic or labetalol 100 to 200 mg orally.

Avoid immediate release oral nifedipine and sublingual nifedipine (unpredictable abrupt falls with stroke and infarction) and aggressive intravenous therapy.

Reduce pressure gradually over 24 to 48 hours (to 160/100 mmHg within 24 to 48 hours then to target over weeks), review in 1 to 7 days, and find the cause (non adherence, interfering drugs, salt, pain, secondary hypertension). Observe for 1 to 2 hours after first doses; treat pain, anxiety and urinary retention first.

Monitoring. Continuous ECG and arterial pressure in emergencies; neurological observations every 15 to 60 minutes initially; urine output hourly; creatinine, electrolytes and troponin at 6 to 12 hours; repeat fundoscopy; stop and reassess if pressure falls too fast.

Referral and escalation. Critical care for infusions and organ support; neurology or neurosurgery for stroke, haemorrhage and encephalopathy; cardiothoracic or vascular surgery for dissection; cardiology for coronary and heart failure; nephrology for kidney injury and malignant hypertension; obstetrics for pre-eclampsia; endocrinology for phaeochromocytoma, aldosteronism and Cushing syndrome; specialist hypertension clinic for secondary cause work up.

Admission. All hypertensive emergencies and all patients with suspected organ damage; pregnancy with 160/110 mmHg or more; pressure over 220/120 mmHg with symptoms; unreliable follow up for urgency.

Safety netting. Return at once for severe headache, visual loss, confusion, fits, chest pain, breathlessness, weakness, speech difficulty, reduced urine, or home pressure over 180/120 mmHg with symptoms. Take medicines every day; do not stop clonidine or beta blockers abruptly; avoid decongestants, NSAIDs, stimulants and excess salt.

Special groups. Pregnancy and postpartum: pre-eclampsia can appear up to 6 weeks after delivery; treat from 160/110 mmHg promptly and consider magnesium sulphate. Children: use age, sex and height percentiles; causes are mostly renal, coarctation and endocrine. Older adults: sensitive to falls in pressure, so use lower doses and slower reduction. Kidney disease: avoid nitroprusside and excessive reduction.

Chronic hypertension: aim to stabilise rather than normalise. Endemic regions: malignant hypertension from glomerular and schistosomal kidney disease, eclampsia, and limited access to intravenous titratable drugs; oral labetalol, nifedipine and captopril are used where infusions are unavailable.