What is the treatment for hypertensive emergency?

Treatment of Hypertensive Emergency

In adults with hypertensive emergency, admission to an intensive care unit is recommended for continuous monitoring of blood pressure and target organ damage with parenteral administration of appropriate antihypertensive agents such as labetalol, nicardipine, or nitroprusside. 1

Definition and Clinical Significance

Hypertensive emergency is defined as severe blood pressure elevation (>180/120 mmHg) associated with evidence of new or worsening target organ damage. If left untreated, it carries a 1-year mortality rate exceeding 79%, with median survival of only 10.4 months 1.

Target organ damage may include:

• Hypertensive encephalopathy
• Intracranial hemorrhage
• Acute ischemic stroke
• Acute myocardial infarction
• Acute left ventricular failure with pulmonary edema
• Unstable angina
• Dissecting aortic aneurysm
• Acute renal failure
• Eclampsia

Initial Management Approach

Blood Pressure Reduction Targets

The approach to BP reduction depends on the specific clinical scenario:

1. For compelling conditions (aortic dissection, severe preeclampsia/eclampsia, pheochromocytoma crisis):

   • Reduce SBP to <140 mmHg during the first hour
   • For aortic dissection, target SBP <120 mmHg 1

2. For patients without compelling conditions:

   • Reduce SBP by no more than 25% within the first hour
   • Then, if stable, to 160/100 mmHg within the next 2-6 hours
   • Cautiously normalize BP over the following 24-48 hours 1

Treatment Setting

Patients with hypertensive emergency should be admitted to an intensive care unit for:

• Continuous BP monitoring
• Assessment of target organ damage
• Parenteral administration of antihypertensive agents 1

Medication Selection by Clinical Presentation

Clinical Presentation	First-Line Treatment	Alternative Options
Malignant hypertension with/without TMA or acute renal failure	Labetalol	Nitroprusside, Nicardipine, Urapidil
Hypertensive encephalopathy	Labetalol	Nitroprusside, Nicardipine
Acute ischemic stroke with BP >220/120 mmHg	Labetalol	Nitroprusside, Nicardipine
Acute hemorrhagic stroke with SBP >180 mmHg	Labetalol	Urapidil, Nicardipine
Acute coronary event	Nitroglycerin	Urapidil, Labetalol
Acute cardiogenic pulmonary edema	Nitroprusside or Nitroglycerin (with loop diuretic)	Urapidil (with loop diuretic)
Acute aortic disease	Esmolol and Nitroprusside or Nitroglycerin	Labetalol or Metoprolol, Nicardipine

1, 2

Recommended Parenteral Medications

Labetalol

• Mechanism: Combined alpha-1 and non-selective beta-receptor antagonist
• Dosing: Initial 0.3-1.0 mg/kg dose (maximum 20 mg) slow IV injection every 10 min or 0.4-1.0 mg/kg/h IV infusion up to 3 mg/kg/h
• Advantages: Predictable BP reduction, maintains cerebral blood flow, no reflex tachycardia 1, 3
• Caution: Avoid in patients with asthma, heart block, or heart failure

Nicardipine

• Mechanism: Dihydropyridine calcium channel blocker
• Dosing: Initial 5 mg/h, increasing every 5 min by 2.5 mg/h to maximum 15 mg/h
• Administration: Slow continuous infusion via central line or large peripheral vein (change site every 12 hours if peripheral) 1, 4
• Advantages: Maintains cerebral and coronary blood flow, predictable response
• Caution: Contraindicated in advanced aortic stenosis

Sodium Nitroprusside

• Mechanism: Nitric oxide-dependent vasodilator
• Dosing: Initial 0.3-0.5 mcg/kg/min; increase in increments of 0.5 mcg/kg/min to achieve BP target; maximum dose 10 mcg/kg/min
• Caution: For infusion rates ≥4-10 mcg/kg/min or duration >30 min, thiosulfate should be co-administered to prevent cyanide toxicity 1
• Monitoring: Intra-arterial BP monitoring recommended to prevent "overshoot"

Important Clinical Considerations

1. Avoid oral therapy for hypertensive emergencies 1

2. Distinguish from hypertensive urgency:

   • Hypertensive urgency: severe BP elevation without acute target organ damage
   • Can be managed with oral medications and does not require ICU admission 1

3. Avoid rapid BP reduction which can lead to:

   • Cerebral hypoperfusion
   • Ischemic stroke
   • Myocardial ischemia 1, 5

4. Monitor closely for:

   • Vital signs (BP every 30 minutes during first 2 hours)
   • Urine output
   • Electrolytes (particularly potassium)
   • Respiratory status and oxygen saturation 2

5. Special populations:

   • Patients with chronic hypertension may tolerate higher BP levels than previously normotensive individuals
   • Elderly patients may require lower dosing of antihypertensive medications 1

Medication Pitfalls to Avoid

1. Short-acting nifedipine should not be used due to risk of rapid, uncontrolled BP falls 1

2. Hydralazine has unpredictable response and prolonged duration of action, making it less desirable for most hypertensive emergencies 1, 6

3. Sodium nitroprusside should be used with caution due to risk of cyanide toxicity with prolonged use 5

4. Nitroglycerin should only be used in patients with acute coronary syndrome and/or acute pulmonary edema; not recommended for volume-depleted patients 1

By following these evidence-based recommendations, clinicians can effectively manage hypertensive emergencies while minimizing risks of complications from either uncontrolled hypertension or overly aggressive treatment.