Intravenous Therapy for Hypertensive Emergencies, Part 1

Denise Rhoney; W. Frank Peacock

Disclosures

Am J Health Syst Pharm. 2009;66(15):1343-1352. 

In This Article

Abstract and Introduction

Abstract

Purpose. Intravenous antihypertensive agents for the treatment of hypertensive emergencies are reviewed.
Summary. An estimated 500,000 people in the United States experience a hypertensive crisis annually. Hypertensive emergency is associated with significant morbidity in the form of end-organ damage. Rapid controlled reduction of blood pressure (BP) may be necessary to prevent or minimize end-organ damage. I.V. antihypertensive agents available for the treatment of hypertensive emergencies are, in general, characterized by a short onset and offset of action and predictable responses during dosage adjustments to reach BP goals, without excessive adjustment or extreme fluctuations in BP. Nicardipine, nitroprusside, fenoldopam, nitroglycerin, enalaprilat, hydralazine, labetalol, esmolol, and phentolamine are i.v. antihypertensive agents recommended for use in hypertensive emergency by the seventh report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure. Since the publication of these recommendations, another i.v. antihypertensive agent, clevidipine, became commercially available. The selection of a specific agent should be based on the agent's pharmacology and patient-specific factors, such as comorbidity and the presence of end-organ damage.
Conclusion. The rapid recognition and initiation of therapy are key to minimizing end-organ damage in patients with hypertensive emergency. Tailoring drug selection according to individual patient characteristics can optimize the management and potential outcomes of patients with hypertensive emergency.

Introduction

Hypertension is a global problem, affecting 50 million people in the United States and 1 billion people worldwide.[1,2] In the United States, as many as 60% of adults over age 18 years are either prehypertensive or hypertensive, according to the seventh report of the Joint National Committee on Prevention, Diagnosis and Treatment of High Blood Pressure (JNC-7) guidelines.[1–3] The Framingham Heart Study found that individuals who are normotensive at age 55 years have a 90% lifetime risk of developing hypertension.[4]

Hypertensive crises include both urgencies and emergencies. Hypertensive emergencies are always associated with end-organ damage, not with a specific level of blood pressure (BP). Hypertensive emergencies are associated with severe elevations in BP (systolic BP [SBP] level of > 180 mm Hg or diastolic BP [DBP] level of > 120 mm Hg) in the presence of impending or progressive end-organ damage, such as neurologic changes, hypertensive encephalopathy, cerebral infarction, intracranial hemorrhage, myocardial ischemia or infarction, acute left ventricular dysfunction, acute pulmonary edema (APE), aortic dissection, renal insufficiency, or eclampsia.[1,2,5] Although data collected in the current era are limited, reports from as far back as the 1950s[6] have consistently shown that approximately 1% of hypertensive patients experience a hypertensive crisis.[7,8] One study of emergency department admissions found that hypertensive crises accounted for 27.5% of all medical emergencies and urgencies in patients arriving at an emergency department, with 77% of these patients having a history of hypertension.[9] A study examined 100 cases of hospital admissions for hypertensive emergency in a New York City hospital.[10] The mean age of this cohort was 52 years (range, 22–87 years), and 66 patients were male. A retrospective review of cases in one hospital in Brazil found 452 patients with hypertensive crisis, representing 0.5% of all clinical–surgical emergencies.[11] Of these, 60.4% were hypertensive urgencies and 39.6% were hypertensive emergencies; 62% of hypertensive urgencies and 44.7% of hypertensive emergencies occurred in women. The rate of hypertensive urgencies peaked in men age 31–60 years and in women age 21–60 years. The rate of hypertensive emergencies peaked in men age 41–70 years and in women age 61–70 years.

Standard treatment for a hypertensive emergency generally includes admission to an intensive care unit (ICU), continuous BP monitoring, and parenteral administration of an antihypertensive agent. Based on JNC-7 guidelines, the general therapeutic goal is to lower the mean arterial pressure (MAP) by 20–25% within 60 minutes, avoiding a precipitous or excessive decrease in BP that may cause iatrogenic renal, cerebral, or coronary ischemia.[1] This recommendation is based on the body's ability to autoregulate tissue perfusion in the brain, heart, and kidneys, which lowers the prevailing BP by 20–25% under normal conditions and during severe hypertension.[12] If the patient is stable, SBP can be further reduced to 160 mm Hg and DBP can be reduced to 100–110 mm Hg over the ensuing 2–6 hours. A gradual reduction to the patient's baseline "normal" BP is targeted over the initial 24–48 hours if the patient is stable, with appropriate monitoring for signs or symptoms of ischemia-related end-organ system deterioration that may accompany changes in SBP, DBP, or MAP.[1,2]

A number of agents in a variety of drug classes are available for the treatment of hypertensive emergencies. This review discusses the i.v. antihypertensive drugs and provides insights and evidence to support their respective clinical applicability in managing emergent hypertensive conditions.

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