Acute Hypertension Management in the Icu

Acute hypertension is a common issue in the intensive care unit (ICU). The settings in which blood pressure elevation occur are highly variable, and optimal care must be tailored to the pathophysiology of the specific circumstances in which it is encountered. The terminology used in the literature to classify this heterogeneous group of disorders has been somewhat inconsistent and confusing (Table 126.1). The terms, hypertensive emergency or hypertensive crisis, are commonly defined as a marked increase in blood pressure associated with target-organ damage, implying that the blood pressure should be lowered emergently. Some authors have reserved the definition of hypertensive emergency for the situation where blood pressure elevation itself is directly responsible for causing end-organ damage. However, clinicians more often need to rapidly lower blood pressure in situations where hypertension, although not necessarily directly responsible for causing the condition, may contribute to deterioration. For example, acute hypertension is usually the result of, rather than the immediate cause of, an acute ischemic stroke. If the patient is to be treated with thrombolytics, it becomes imperative to maintain the blood pressure within certain narrow limits to minimize the risk of hemorrhagic transformation while at the same time not compromising cerebral blood flow (CBF). Thus, in this chapter, we define a hypertensive emergency broadly—as any condition in which blood pressure should be lowered immediately. Although the term, malignant hypertension, has been discouraged by some, it is still widely used in the literature to describe the syndrome where organ dysfunction is a direct consequence of the elevated blood pressure, rather than an epiphenomenon. The presence of papilledema is not necessarily required for this diagnosis to be made (1,2). In contrast, a hypertensive urgency is defined as a condition with severe blood pressure elevation and no target-organ damage, such that the blood pressure can be decreased more gradually over the course of several hours, often with oral medications. It is therefore the presence or absence of organ dysfunction, rather than the absolute degree of blood pressure elevation, that determines whether a patient is classified as having a hypertensive emergency or urgency. It is not always clear how clinicians distinguish between hypertensive urgencies and the situation where a patient simply has severe, poorly controlled, chronic hypertension. The most recent Joint National Committee Guidelines (JNV 7) classify patients with hypertension into stage 1 (systolic blood pressure [SBP] 140–159 mm Hg or diastolic blood pressure [DBP] 90–99 mm Hg) and stage 2 (SBP exceeding 160 mm Hg or DBP exceeding 100 mm Hg). The previously used category of “stage 3 hypertension” (SBP exceeding 180 mm Hg or DBP exceeding 110 mm Hg) has been combined with stage 2 (3).