What is the approach to managing a hypertensive emergency?

Management of Hypertensive Emergency

Hypertensive emergencies require immediate hospitalization in an intensive care unit for continuous BP monitoring and parenteral administration of appropriate antihypertensive agents to prevent or limit further target organ damage. 1

Definition and Classification

• Hypertensive emergency: Severe BP elevation (>180/120 mmHg) with evidence of new or worsening target organ damage
• Hypertensive urgency: Severe BP elevation without evidence of acute target organ damage
• Mortality risk: Untreated hypertensive emergencies have >79% 1-year mortality rate with median survival of only 10.4 months 2

Initial Assessment

• Evaluate for target organ damage:

  • Neurological: Hypertensive encephalopathy, stroke, intracranial hemorrhage
  • Cardiovascular: Acute coronary syndrome, acute heart failure, pulmonary edema, aortic dissection
  • Renal: Acute kidney injury, acute renal failure
  • Other: Eclampsia, microangiopathic hemolytic anemia

• Key diagnostic tests:

  • Physical examination
  • Laboratory tests (renal panel, CBC)
  • ECG
  • Additional testing based on symptoms (echocardiogram, neuroimaging, chest CT)

Blood Pressure Reduction Targets

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

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

2. For other hypertensive emergencies:

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

Medication Selection by Clinical Presentation

First-Line IV Medications by Condition:

Clinical Presentation	First-Line Treatment	Alternative
Most hypertensive emergencies	Labetalol	Nicardipine
Acute coronary event	Nitroglycerin	Labetalol
Acute pulmonary edema	Nitroglycerin + loop diuretic	Labetalol + loop diuretic
Aortic dissection	Esmolol + Nitroprusside	Labetalol, Nicardipine
Malignant hypertension with/without acute renal failure	Labetalol	Nicardipine, Nitroprusside
Hypertensive encephalopathy	Labetalol	Nicardipine, Nitroprusside
Acute ischemic stroke (BP >220/120 mmHg)	Labetalol	Nicardipine
Acute hemorrhagic stroke (SBP >180 mmHg)	Labetalol	Nicardipine

IV Antihypertensive Medication Administration

Nicardipine

• Initial dose: 5 mg/h
• Titration: Increase every 5 min by 2.5 mg/h
• Maximum dose: 15 mg/h
• Administration: Slow continuous infusion via central line or large peripheral vein
• Change infusion site every 12 hours if administered via peripheral vein 3

Clevidipine

• Initial dose: 1-2 mg/h
• Titration: Double every 90 seconds until BP approaches target
• Maximum dose: 32 mg/h
• Maximum duration: 72 hours 4

Sodium Nitroprusside

• Initial dose: 0.3-0.5 mcg/kg/min
• Titration: Increase in increments of 0.5 mcg/kg/min
• Maximum dose: 10 mcg/kg/min
• Duration: As short as possible
• For infusion rates ≥4-10 mcg/kg/min or duration >30 min, consider thiosulfate coadministration to prevent cyanide toxicity 1
• Caution: Should be avoided when possible due to toxicity concerns 5

Labetalol

• Initial dose: 0.3-1.0 mg/kg (maximum 20 mg) slow IV injection every 10 min
• Alternative: 0.4-1.0 mg/kg/h IV infusion up to 3 mg/kg/h
• Adjust rate up to total cumulative dose of 300 mg
• Can be repeated every 4-6 hours 1

Esmolol

• Loading dose: 500-1000 mcg/kg/min over 1 min
• Followed by: 50 mcg/kg/min infusion
• Titration: Repeat bolus and increase infusion in 50 mcg/kg/min increments
• Maximum dose: 200 mcg/kg/min 1

Monitoring and Transition to Oral Therapy

1. During acute management:

   • Continuous BP monitoring in ICU
   • Monitor for signs of hypoperfusion or excessive BP reduction
   • Adjust infusion rates as needed

2. Transition to oral therapy:

   • When BP is stable, begin transition to oral antihypertensive agents
   • Consider overlapping IV and oral therapy briefly to ensure smooth transition
   • When switching to nicardipine capsules, administer first oral dose 1 hour prior to discontinuing infusion

3. Follow-up:

   • Monitor for at least several hours after stabilization before discharge
   • Schedule follow-up within 24 hours
   • Continue with monthly follow-up until target BP is reached
   • Monitor for regression of hypertension-mediated organ damage

Important Caveats

• Avoid overly aggressive BP reduction, which can lead to cerebral, cardiac, or renal hypoperfusion
• Avoid sodium nitroprusside when possible due to risk of cyanide toxicity
• Avoid nifedipine, hydralazine, and oral agents as first-line therapy for hypertensive emergencies
• For pregnant patients with hypertensive crisis, use IV labetalol or nicardipine with magnesium
• For stimulant intoxication with autonomic hyperreactivity, consider benzodiazepines before antihypertensive therapy