Hypertensive Emergencies and Urgencies:

About 20% to 30% of adults in developed countries have hypertension.¹ Because of the high prevalence of this condition, it is not uncommon to encounter patients with elevated blood pressure (BP) in the primary care setting. Although the greatest impact of hypertension on health results from its long-term effects, some patients present with markedly elevated BP that requires emergent intervention.

Thus, the challenge is to distinguish nonurgent BP elevations from those that demand immediate attention. Here we discuss the clues that signal target organ damage, and we provide a detailed road map for the workup.

DEFINITIONS

The National Heart, Lung, and Blood Institute's Joint National Committee recently defined hypertensive emergencies and urgencies in their most recent guidelines (JNC 7).² A hypertensive emergency requires immediate BP reduction (although not necessarily to the reference range) with parenteral antihypertensives to limit target organ damage (namely, damage to the brain, heart, kidneys, or eyes). In a patient with a hypertensive urgency, the marked elevation in BP is not associated with target organ damage; however, the risk of such damage is very high.³ Combination oral antihypertensive therapy should be started when a hypertensive urgency is diagnosed.²

CLINICAL EVALUATION

The clinical presentation of a hypertensive emergency reflects the consequences of elevated BP on the target organs. The extent of such consequences depends on how high and how quickly the BP has risen, whether the patient has a history of hypertension, and whether comorbid conditions are present.

The evaluation of a patient in whom a hypertensive emergency or urgency is suspected has 2 chief aims (Table 1):

• Assessment of target organ damage and/or risk of such damage.
• Determination of the cause of the acute elevation in BP (if possible).

History. A primary purpose of the history taking is to assess the severity of symptoms-which can help gauge the extent of target organ damage. Symptoms that suggest a cardiovascular problem include:

• Chest pain and/or syncope (suggests myocardial ischemia/unstable angina or aortic dissection).
• Back pain (suggests aortic dissection).
• Dyspnea (suggests pulmonary edema or congestive heart failure).

Symptoms that suggest a neurologic problem include:

• Seizure/altered mental status (suggests hypertensive encephalopathy).
• Focal weakness and/or speech change (suggests cerebrovascular accident or transient ischemic attack).
• Headache and/or visual disturbance (suggests CNS compromise).

Symptoms that suggest a renal problem include:

• Decreased urinary output.
• Bloody or frothy urine.
• Nonspecific abdominal pain.
• Malaise.

If the patient has a history of hypertension, find out when BP elevations began, how the hypertension has been treated, what degree of BP control was achieved, and whether there has been any previous target organ damage. This information can help assess risk and guide treatment. For example, patients with chronic hypertension in whom a hypertensive emergency develops are more likely to experience cerebral ischemia and other negative consequences if BP is reduced abruptly. Hypertensive patients may have poor outcomes even if their BP is reduced to a range tolerated by most normotensive persons.⁴

A thorough history taking also attempts to uncover the cause of acutely elevated BP (Table 2). To investigate possible toxicologic causes, ask about:

• Recent illicit drug use (eg, cocaine, methamphetamine).
• Recent sympathomimetic use.
• Concurrent use of monoamine oxidase inhibitors and ingestion of foods that contain tyramine (eg, wine, aged cheese, and canned meats).

To investigate possible iatrogenic causes, inquire about:

• Use of exogenous glucocorticoid therapy (which can precipitate Cushing syndrome).
• Use of weight loss medications (either prescription or over-the-counter).
• Discontinuation of antihypertensive medications (especially clonidine and β-blockers).

Physical examination. Measure BP in both standing and supine positions to detect volume depletion. In addition, obtain BP readings in both arms; a significant difference in these values suggests aortic dissection.

Perform a funduscopic examination in any patient in whom a hypertensive emergency is suspected. New hemorrhages, exudates, and papilledema all suggest a hypertensive emergency (Figure).

In the cardiovascular examination, check for signs of heart failure, such as jugular venous distension, crackles, third heart sound, or gallop.

During the neurologic examination, be alert for evidence of encephalopathy or ischemia. Assess the patient's level of consciousness, look for signs of meningismal irritation, perform visual fields testing, check for pronator drift, and evaluate motor and sensory function.

Laboratory and imaging studies. In addition to the history taking and physical examination, these may be useful in the assessment of a severely hypertensive patient. Base your selection of studies for a particular patient on the history and physical examination findings.

Measurement of electrolyte, blood urea nitrogen, and creatinine levels can help assess kidney function and volume status. Urinalysis can also provide useful clues to the presence of kidney disease (for example, proteinuria, hematuria, and/or red blood cell casts). However, isolated red blood cells in the urine of a patient with significantly elevated BP do not necessarily indicate a hypertensive emergency. Consultation with a nephrologist may be beneficial in this setting.

An ECG can provide evidence of ischemia or infarction. A chest radiograph can show signs of left ventricular heart failure (pulmonary edema) or aortic dissection (widened medias-tinum). If neurologic symptoms are present, a head CT or MRI scan may be needed to rule out focal lesions.

A complete blood cell count that reveals the presence of schistocytes indicates hemolysis, which is thought to be a clue to associated vascular injury (such injury leads to fibrin strand formation and the shearing of red blood cells). Although preeclampsia and eclampsia usually develop in the second or third trimester, it is wise to order a urine test for human chorionic gonadotropin in any woman who is or might be pregnant.

Finally, if the evaluation to determine whether an acute BP elevation represents a hypertensive emergency or urgency cannot be completed in the office, arrange for the patient to be transferred to an emergency facility.

TREATMENT

In contrast to their central role in the treatment of chronic hypertension, office practitioners have a limited role in the treatment of acute hypertension. In this setting, their primary responsibility is to accurately distinguish between hypertensive emergencies, hypertensive urgencies, and nonurgent elevations in BP.

In hypertensive emergencies, BP reduction is performed in the emergency department or ICU. Once a hypertensive emergency is identified, arrange for immediate transfer of the patient to an emergency facility via an Advanced Cardiac Life Support (ACLS)-certified transport vehicle. Make sure all pertinent records and test results accompany the patient. A phone call to the emergency facility alerting them to the patient's arrival is appropriate.

The treatment goal in a hypertensive emergency is usually a reduction of mean arterial pressure (MAP) by 20% to 25% over 60 minutes (MAP = Z\c [SBP − DSP], where SBP is systolic blood pressure and DBP is diastolic blood pressure). This is best accomplished with easily titratable intravenous medications (Table 3) and close monitoring.

In a hypertensive urgency, blood pressure need not be reduced emergently. Initiate oral antihypertensive therapy with frequent outpatient BP monitoring and adjustment of medications as needed. Select agents that address the underlying pathology and comorbidities (Table 4). Whenever possible, increase the dosage of existing antihypertensive therapy.

You may determine that a case of acute hypertension is nonemergent. There is no evidence to support short-term treatment in this setting; however, long-term antihypertensive therapy is essential. Not having a primary care physician has been shown to be the most important risk factor for presentation to a hospital emergency department with severely elevated BP.⁵

References:

REFERENCES:

1. He J, Whelton PK. Epidemiology and prevention of hypertension. Med Clin North Am. 1997;81: 1077-1097.

2. Chobanian AV, Bakris GL, Black HR, et al, for the National Heart, Lung, and Blood Institute Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure; National High Blood Pressure Education Program Coordinating The Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation and Treatment of High Blood Pressure: the JNC report. JAMA. 2003;289:2560-2572.

3. Shayne PH, Pitts SR. Severely increased blood pressure in the emergency department. Ann Emerg Med. 2003;41:513-529.

4. Elliott WJ. Hypertensive emergencies. Crit Care Clin. 2001;17:435-451.

5. Shea S, Misra D, Francis CK. Predisposing factors for severe, uncontrolled hypertension in an inner-city minority population. N Engl J Med. 1992; 327:776-781.

6. Vaughn CJ, Delanty N. Hypertensive emergencies. Lancet. 2000;356:411-417.