What is the initial management of a hypertensive emergency?

Initial Management of Hypertensive Emergency

In adults with hypertensive emergency, immediate admission to an intensive care unit is recommended for continuous monitoring of blood pressure and target organ damage, with parenteral administration of an appropriate intravenous antihypertensive agent. 1

Definition and Diagnosis

• A hypertensive emergency is defined as a severe elevation in blood pressure (>180/120 mmHg) associated with evidence of new or worsening target organ damage 1, 2
• The diagnosis is based not only on the absolute blood pressure value but also on the presence of acute end-organ damage 2, 3
• Without evidence of acute target organ damage, the condition is classified as a hypertensive urgency, which can be managed with oral medications 2

Initial Assessment and Monitoring

• Evaluate for evidence of target organ damage affecting the heart, brain, kidneys, eyes, and large blood vessels 2
• Common presentations include:
  • Cardiac: acute pulmonary edema, coronary ischemia/acute myocardial infarction 2
  • Neurological: hypertensive encephalopathy, acute stroke (ischemic or hemorrhagic) 2
  • Renal: acute kidney failure, thrombotic microangiopathy 2
  • Retinal: advanced hypertensive retinopathy (grade III-IV) 2
  • Vascular: acute aortic disease (aneurysm or dissection) 2
• Continuous blood pressure monitoring, ideally via intra-arterial line, is recommended 3

Blood Pressure Reduction Goals

• For patients without compelling conditions, SBP should be reduced by no more than 25% within the first hour 1, 2
• Then, if stable, aim for 160/100 mmHg within the next 2-6 hours 1, 3
• Finally, cautiously reduce to normal during the following 24-48 hours 1
• For compelling conditions (aortic dissection, severe preeclampsia/eclampsia, pheochromocytoma crisis), SBP should be reduced to <140 mmHg during the first hour and to <120 mmHg in aortic dissection 1

First-Line Intravenous Medications

• Nicardipine: Initial dose 5 mg/h, increasing every 5 minutes by 2.5 mg/h to maximum 15 mg/h 1, 4

  • Advantages: Easily titratable, minimal effects on heart rate, can be used in most hypertensive emergencies 4
  • Administration: Must be diluted before infusion (25 mg in 240 mL of compatible IV fluid) to achieve 0.1 mg/mL concentration 4

• Labetalol: Initial 0.3-1.0 mg/kg dose (maximum 20 mg) slow IV injection every 10 minutes or 0.4-1.0 mg/kg/h IV infusion up to 3 mg/kg/h 1, 5

  • Advantages: Combined alpha and beta blockade, particularly useful for hypertensive encephalopathy, malignant hypertension, and acute stroke 2, 5
  • Caution: Avoid in patients with asthma, COPD, heart block, or bradycardia 5

Medication Selection Based on Specific End-Organ Damage

• Hypertensive encephalopathy: Labetalol is preferred 2, 3
• Acute coronary syndrome: Nitroglycerin is preferred (initial 5 μg/min, increase in increments of 5 μg/min every 3-5 minutes to maximum 20 μg/min) 1, 3
• Acute pulmonary edema: Nitroglycerin or sodium nitroprusside 2, 3
• Acute aortic dissection: Esmolol plus nitroprusside or nitroglycerin 2
• Acute stroke: Labetalol for both ischemic (if BP >220/120 mmHg) and hemorrhagic (if SBP >180 mmHg) stroke 2

Important Precautions

• Excessive blood pressure reductions can lead to renal, cerebral, or coronary ischemia and should be avoided 2
• Short-acting nifedipine is not recommended for hypertensive emergencies 2
• Sodium nitroprusside should be used with caution due to potential cyanide toxicity, especially at infusion rates ≥4-10 μg/kg/min or for durations >30 minutes 1
• Large blood pressure reductions (>50% decrease in mean arterial pressure) have been associated with ischemic stroke and death 2
• Change infusion site every 12 hours if administered via peripheral vein 4

Transition to Oral Therapy

• Oral antihypertensive therapy can usually be initiated after 6-12 hours of successful parenteral therapy 6
• When switching to oral nicardipine, administer the first dose 1 hour prior to discontinuation of the infusion 4