How is blood pressure managed in a hypertensive emergency?

Management of Blood Pressure in Hypertensive Emergency

In a hypertensive emergency, patients should be admitted to an intensive care unit for continuous blood pressure monitoring and parenteral administration of appropriate antihypertensive agents. 1, 2

Definition and Initial Assessment

• Hypertensive emergency: Severe BP elevation (>180/120 mmHg) with evidence of new or worsening target organ damage
• Untreated hypertensive emergencies have >79% one-year mortality rate with median survival of only 10.4 months 1, 2
• Evaluate for end-organ damage through physical examination, laboratory tests, ECG, and additional testing based on symptoms

Blood Pressure Reduction Targets

For Compelling Conditions:

• Aortic dissection: Reduce SBP to <140 mmHg during first hour, then to <120 mmHg 1, 2
• Severe preeclampsia/eclampsia: Reduce SBP to <140 mmHg during first hour 1
• Pheochromocytoma crisis: Reduce SBP to <140 mmHg during first hour 1

For Other Hypertensive Emergencies:

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

First-Line Parenteral Medications

Nicardipine (Calcium Channel Blocker)

• Initial dose: 5 mg/h, increasing every 5 min by 2.5 mg/h to maximum 15 mg/h 1, 3
• Advantages: No dose adjustment needed for elderly; contraindicated in advanced aortic stenosis 1
• Administration: Slow continuous infusion via central line or large peripheral vein; change infusion site every 12 hours if peripheral 3

Labetalol (Combined Alpha and Beta Blocker)

• First-line for most hypertensive emergencies, hypertensive encephalopathy, and acute stroke 2
• Mechanism: Combined alpha and beta blockade produces dose-related falls in BP without reflex tachycardia 4
• Initial dose: 0.25 mg/kg IV, followed by 0.5 mg/kg every 15 minutes as needed 4
• Maximal effect occurs within 5 minutes of each dose 4

Other Important Agents

• Esmolol: First-line for aortic dissection (with nitroprusside); loading dose 500-1000 mcg/kg/min over 1 min followed by 50 mcg/kg/min infusion 2
• Sodium nitroprusside: Initial 0.3-0.5 mcg/kg/min; increase in increments of 0.5 mcg/kg/min; maximum dose 10 mcg/kg/min; use for shortest duration possible due to cyanide toxicity risk 1, 2
• Clevidipine: Newer agent with advantages in hypertensive emergencies; initial 1-2 mg/h, doubling every 90s until BP approaches target 1, 5

Specific Clinical Scenarios

Clinical Presentation	First-Line Treatment	Alternative
Acute coronary event	Nitroglycerin	Labetalol
Acute pulmonary edema	Nitroglycerin + loop diuretic	Labetalol + loop diuretic
Aortic dissection	Esmolol + Nitroprusside	Labetalol, Nicardipine
Hypertensive encephalopathy	Labetalol	Nicardipine, Nitroprusside
Acute ischemic stroke (BP >220/120 mmHg)	Labetalol	Nicardipine
Acute hemorrhagic stroke (SBP >180 mmHg)	Labetalol	Nicardipine

Important Considerations and Pitfalls

• Avoid sodium nitroprusside when possible due to cyanide toxicity risk, especially for prolonged use 5, 6
• Avoid immediate-release nifedipine, hydralazine, and nitroglycerin as first-line agents due to unpredictable responses and adverse effects 5, 6
• Monitor closely when titrating medications in patients with congestive heart failure or impaired hepatic/renal function 3
• In patients with autonomic hyperreactivity due to stimulant intoxication, administer benzodiazepines before antihypertensive therapy 2
• Distinguish between hypertensive emergency (requiring immediate IV therapy) and hypertensive urgency (severe BP elevation without acute end-organ damage, which can be managed with oral medications) 6, 7

Transition to Oral Therapy

• Oral antihypertensive therapy can usually be initiated after 6-12 hours of parenteral therapy 7
• When switching from IV nicardipine to oral nicardipine capsules, administer first oral dose 1 hour prior to discontinuation of infusion 3