What are the criteria and treatment for a hypertensive emergency?

Hypertensive Emergency Criteria

A hypertensive emergency is defined as blood pressure exceeding 180/120 mmHg WITH evidence of acute target organ damage—the presence of organ damage, not the absolute BP number, is what distinguishes an emergency from urgency and mandates immediate ICU admission with IV therapy. 1, 2

Diagnostic Criteria

Blood Pressure Threshold

• BP >180/120 mmHg is the numerical cutoff, though the rate of BP rise may be more clinically significant than the absolute value 1, 2
• Patients with chronic hypertension often tolerate higher pressures than previously normotensive individuals 1

Critical Distinguishing Feature: Target Organ Damage

The presence of acute or worsening target organ damage is what defines a hypertensive emergency and separates it from hypertensive urgency 1, 2:

Neurologic damage: 1, 2

• Hypertensive encephalopathy (altered mental status, headache, visual disturbances, seizures)
• Intracranial hemorrhage
• Acute ischemic stroke

Cardiac damage: 1, 2

• Acute myocardial infarction
• Acute left ventricular failure with pulmonary edema
• Unstable angina

Vascular damage: 1, 2

• Aortic dissection or aneurysm

Renal damage: 1, 2

• Acute kidney injury
• Hypertensive thrombotic microangiopathy (malignant hypertension)

Ophthalmologic damage: 1, 2

• Retinal hemorrhages, cotton wool spots, papilledema on fundoscopy

Obstetric: 1, 2

• Severe preeclampsia or eclampsia

Essential Diagnostic Workup

Laboratory Tests

Obtain immediately to assess for target organ damage 1:

• Complete blood count (hemoglobin, platelets) to detect microangiopathic hemolytic anemia
• Basic metabolic panel (creatinine, sodium, potassium) for renal function and electrolytes
• Lactate dehydrogenase (LDH) and haptoglobin to identify hemolysis in thrombotic microangiopathy
• Urinalysis with microscopy for proteinuria and abnormal sediment
• Troponins if chest pain present
• Electrocardiogram to assess cardiac involvement

Additional Investigations Based on Presentation 1

• Fundoscopy for retinal hemorrhages, exudates, papilledema
• Chest X-ray for pulmonary edema or aortic abnormalities
• CT/MRI brain if neurologic symptoms present
• Echocardiogram if cardiac dysfunction suspected
• CT-angiography if aortic dissection suspected

Immediate Management

Triage Decision

If target organ damage present: Hypertensive emergency → ICU admission with continuous arterial BP monitoring and IV antihypertensive therapy 1, 2

If NO target organ damage: Hypertensive urgency → oral antihypertensives with outpatient follow-up in 2-4 weeks 1

Blood Pressure Reduction Targets

Standard approach (most hypertensive emergencies): 1, 2

• Reduce mean arterial pressure by 20-25% within the first hour
• Then if stable, reduce to 160/100 mmHg over 2-6 hours
• Cautiously normalize over 24-48 hours

Special situations requiring different targets: 1, 2

• Aortic dissection: Reduce SBP to <120 mmHg within 20 minutes AND heart rate <60 bpm
• Acute pulmonary edema: Reduce SBP to <140 mmHg immediately
• Acute ischemic stroke: Avoid BP reduction unless >220/120 mmHg (withhold treatment for first 5-7 days)
• Intracerebral hemorrhage: If SBP ≥220 mmHg, carefully lower to 140-160 mmHg within 6 hours

First-Line IV Medications

Nicardipine (preferred for most situations): 1, 2, 3

• Initial dose: 5 mg/hr IV infusion
• Titrate by 2.5 mg/hr every 15 minutes
• Maximum: 15 mg/hr
• Advantages: Predictable titration, maintains cerebral blood flow, does not increase intracranial pressure

Labetalol (excellent for renal involvement, encephalopathy): 1, 2, 4

• Bolus: 20-80 mg IV every 10 minutes, OR
• Infusion: 0.4-1.0 mg/kg/hr (2-4 mg/min)
• Avoid in acute heart failure, severe bradycardia, or heart block

Clevidipine: 1, 2

• Initial: 1-2 mg/hr IV
• Double every 90 seconds until BP approaches target
• Maximum: 32 mg/hr
• Contraindicated in soy/egg allergies or lipid disorders

Critical Pitfalls to Avoid

Do NOT lower BP too rapidly: Excessive drops >70 mmHg systolic can precipitate cerebral, renal, or coronary ischemia, particularly in patients with chronic hypertension who have altered autoregulation 1, 2

Avoid these medications: 1, 2

• Immediate-release nifedipine: Unpredictable precipitous BP drops, reflex tachycardia
• Sodium nitroprusside: Risk of cyanide/thiocyanate toxicity (use only as last resort)
• Hydralazine: Unpredictable effects (except in eclampsia/preeclampsia where it's safe)

Do NOT use oral agents for initial management: Hypertensive emergencies require IV therapy for reliable, titratable control 2

Do NOT treat the BP number alone: Always assess for true target organ damage before aggressive treatment—many patients with acute pain or distress have transiently elevated BP that normalizes when the underlying condition is treated 1

Prognostic Significance

Without treatment, hypertensive emergencies carry a 1-year mortality rate >79% with median survival of only 10.4 months, emphasizing the critical importance of prompt recognition and appropriate management 1, 2