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Definition of Terms

The Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC-7) redefined chronic hypertension into three classifications: prehypertension, stage 1 hypertension, and stage 2 hypertension1 (Table 61-1).

Table 61-1 JNC-7 Classification of Hypertension

These classifications are tied to diagnostic and treatment recommendations in the report. The JNC-7 classification refers to blood pressure based on the average of two or more properly measured blood pressure readings taken in a seated patient on each of two or more office visits, a specification that cannot be reproduced in the ED. However, knowledge of the JNC-7 criteria helps emergency physicians to understand preferred management of chronic hypertension, including the expected intensity of medical therapy required to control an individual patient’s blood pressure. For example, a patient meeting criteria for stage 2 hypertension can be expected to require at least two medications to control blood pressure.1

Hypertensive emergency is an acute elevation of blood pressure (≥180/120 mm Hg) associated with end-organ damage, specifically, acute effects on the brain, heart, aorta, kidneys, and/or eyes1 (Table 61-2; Figure 61-1). Epidemiologic studies of this condition are hampered by the fact that no diagnostic code exists to differentiate hypertensive emergency from less serious clinical presentations associated with hypertension, despite the need for such a code.2

Table 61-2 Hypertensive Emergencies

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