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Nursing:
doi: 10.1097/01.NURSE.0000347077.30256.14
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Taking aim at hypertensive crises

Horne, Eva M. RN, FNP-C, BSN, MN; Gordon, Paula M. RN, MS

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At Georgia State University's Byrdine F. Lewis School of Nursing in Atlanta, Eva M. Horne is a clinical assistant professor and Paula M. Gordon is a clinical instructor.

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Abstract

Your patient's BP is severely elevated. Here's how to respond appropriately to protect target organs.

ACCOMPANIED BY HIS WIFE, Amos Ross, 52, arrives in the ED via ambulance. Mr. Ross complains of a frontal headache, which he rates as a 7 on a pain intensity rating scale of 0 (no pain) to 10 (worst pain imaginable). He also complains of blurred vision. Mrs. Ross says her husband ran out of his hypertension medications 2 weeks ago and didn't refill them.

After quickly assessing his ABCs, you take his vital signs while a colleague connects him to the cardiac monitor and obtains I.V. access. His BP is 210/115 mm Hg in the right arm and 212/118 mm Hg in the left arm with no orthostatic changes; heart rate, 100 beats/minute; sinus tachycardia without ectopy; temperature, 98.4° F (36.9° C) orally; respirations, 16 and regular; and Spo2, 94% on room air. He denies shortness of breath, chest pain, or other discomfort besides a headache.

You immediately inform the ED physician, who performs a focused history and physical and orders supplemental oxygen, an I.V. infusion of nitroprusside, a stat 12-lead ECG, portable chest X-ray, unenhanced computed tomography (CT) scan of the head, and lab work. He also orders admission to the CCU for further monitoring and management.

Continuing your assessment, you note bilateral 2+ pitting pedal and ankle edema, bilateral inspiratory crackles in the lower lung fields, and bilateral jugular vein distension. Heart sounds are normal, with the exception of an S3. You start the nitroprusside infusion as ordered and call the CCU with the report. Mr. Ross is admitted with hypertensive crisis.

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Figure. Mechanisms o...
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What are hypertensive crises?

According to the Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (also known as the JNC 7), hypertensive crises are categorized as hypertensive emergencies or hypertensive urgencies. The difference between hypertensive emergencies and urgencies isn't the BP measurement itself, but the presence or absence of target organ damage. Here's how they compare.

Hypertensive emergencies are characterized by severe elevations in BP (greater than 180/120 mm Hg) with evidence of impending or progressive target organ damage (more on this shortly). The management goal is to reduce the patient's mean arterial pressure by no more than 25% in the first 2 hours, then, if he's stable, to reduce it to 160/100 to 110 mm Hg over the next 2 to 6 hours.1 The patient should be admitted to an ICU or CCU for parenteral drug therapy and continuous monitoring of neurologic, cardiovascular, and hemodynamic status. About one-third of patients who come to the ED with hypertensive crises are diagnosed with hypertensive emergency.1

Hypertensive urgencies are characterized by a severe elevation in BP without evidence of target organ damage. The patient may have a severe headache, shortness of breath, epistaxis, or severe anxiety. In this case, the initial goal is to reduce BP to 160/110 mm Hg over several hours to days. Most patients with hypertensive urgency can be managed as outpatients using oral antihypertensive drugs.2

Anyone with hypertension is at risk for a hypertensive crisis; an estimated 1% to 2% of patients with hypertension will have a hypertensive crisis sometime in their life.3 Most of these patients have long-standing essential hypertension that hasn't been optimally managed. (For information on hypertension, see Mechanisms of BP regulation.) Many, like Mr. Ross, abruptly discontinue their antihypertensive medications for various reasons. As with hypertension in general, hypertensive crises tend to be more common among African-Americans, older adults, and men. For more on the risk factors for hypertension, see About hypertension. For details about how the JNC 7 classifies BP, see Stages of hypertension.

Other causes of hypertensive crises include head injury, pheochromocytoma, combining a monoamine oxidase inhibitor and foods containing tyramine, eclampsia/severe preeclampsia, substance abuse (for example, cocaine intoxication), renal parenchymal disease, and renovascular disease.2

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Organs in peril

Let's take a closer look at how hypertension damages target organ systems (heart, arterial blood vessels, kidneys, and brain).

* Cardiovascular. Increased left ventricular workload created by chronic hypertension causes compensatory left ventricular hypertrophy and possibly left-sided heart failure. Hypertension also accelerates the atherosclerotic process, leading to myocardial ischemia or myocardial infarction (MI). The accelerated atherosclerotic process also damages the aorta and lower extremity vessels. Possible complications include dissecting aortic aneurysms, peripheral arterial disease, and eventual critical limb ischemia.

* Renal. The atherosclerotic and hypertrophic changes associated with hypertension affect renal blood flow, decreasing renal perfusion and leading to renal dysfunction and eventual renal failure. The decreased renal blood flow caused by cardiovascular changes also activates the renin-angiotensin-aldosterone system. This causes sodium and water retention, increasing circulating blood volume, sympathetic nervous system activation, and vasoconstriction, further perpetuating hypertensive disease.

* Neurologic. Decreased cerebral blood flow, vascular occlusions, and weakened blood vessels caused by hypertension can lead to transient ischemic attacks, strokes, cerebral aneurysms, and intracerebral hemorrhage.

The generalized reduced blood flow and the increased arteriolar pressure caused by hypertension also affects the eyes. These changes can cause retinal vascular sclerosis and hemorrhage leading to vision loss.

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Assessing your patient

Elevated BP alone rarely requires emergency therapy, so your initial triage should focus on identifying patients who have a severely elevated BP with evidence of target organ damage, such as myocardial ischemia or MI, pulmonary edema, intracerebral hemorrhage, or acute ischemic stroke.4

Start with the patient's history, to assess for symptoms suggesting target organ damage; for example, chest discomfort (myocardial ischemia or MI), back pain (aortic dissection), altered level of consciousness, headache, visual disturbances (hypertensive encephalopathy), or shortness of breath (heart failure, pulmonary edema). Ask about a family history of heart disease, hypertension, diabetes, dyslipidemia, stroke, and kidney failure. When you perform medication reconciliation, include the patient's use of nicotine, alcohol, herbal products, nonprescription medication and supplements, and illicit drugs. Specifically ask about his antihypertensive therapy and whether he's adhered to his medication regimen.

When you perform a physical exam, look for signs and symptoms of target organ damage. Take the patient's vital signs, obtaining BP readings in both arms using an appropriately sized cuff. (A too-small cuff can falsely elevate BP readings, especially in obese patients; a too-large cuff can falsely lower BP readings.) Use an appropriately sized cuff (cuff bladder encircling at least 80% of the arm) to ensure accuracy.1

You may see distended neck veins and auscultate a carotid bruit. Cardiac assessment may reveal murmurs, extra heart sounds, or laterally displaced apical impulse. Pulmonary crackles and peripheral edema may indicate heart failure. Assess the patient's abdomen for abnormal aortic pulsations, masses, and renal artery bruits. Perform a focused neurologic exam to assess mental status and weakness. Report abnormalities promptly to the healthcare provider.

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Diagnostic testing

The healthcare provider will order lab and imaging studies based on patient history and physical exam findings.

Serum electrolytes, blood urea nitrogen, and creatinine levels can help assess kidney function and provide clues to kidney disease. A urinalysis can reveal proteinuria, hematuria, red blood cell casts, and tubular casts indicating renal dysfunction.

A 12-lead ECG can help identify myocardial ischemia or MI, dysrhythmias, and left ventricular hypertrophy. A chest X-ray can identify pulmonary edema, a widened mediastinum, or cardiomegaly. An echocardiogram can provide valuable information about the patient's systolic and diastolic left ventricular function and identify valvular heart disease, chamber size, and regional wall abnormalities. A stat CT scan will be ordered if the clinical picture is consistent with aortic dissection (sudden onset of severe ripping or tearing chest pain, a difference in arm BPs of greater than 20 mm Hg, unequal pulses, widened mediastinum).5

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Managing a hypertensive emergency

When managing the patient's BP, remember that reducing it too rapidly may result in cardiac or cerebrovascular hypoperfusion, leading to MI or stroke.

Because of compensatory pressure natriuresis (increased renal sodium and water excretion in response to elevated BP), a patient with hypertensive emergency may have significant sodium and volume depletion. Slow, cautious volume expansion with I.V. 0.9% sodium chloride solution can help restore organ perfusion and prevent an abrupt decline in BP when antihypertensive medication therapy is initiated.

Patients with a hypertensive emergency are best managed with a continuous I.V. infusion of a short-acting, titratable antihypertensive agent (see Drugs used in hypertensive emergencies). Avoid the sublingual and I.M. routes because the pharmacodynamics of antihypertensive drugs administered by these routes are unpredictable.3

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No large clinical trials have determined the optimal pharmacologic therapy in patients with hypertensive emergency, so treatment should be individualized based on the patient's clinical status and target organ damage.6 Use extreme caution to avoid reducing the patient's BP too rapidly. Excessive BP correction can further reduce target organ perfusion and compound injury.

Once stable BP control is established with I.V. drugs and signs and symptoms of target organ damage have resolved, start the patient on oral antihypertensive therapy as ordered as the I.V. drugs are gradually discontinued.3

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Managing hypertensive urgency

Most patients with hypertensive crisis have no evidence of target organ damage and are diagnosed with hypertensive urgency.3 Many are asymptomatic aside from severely elevated BP and can be treated and observed briefly in the ED. During this time, oral antihypertensive medications can be resumed (or started, for patients who hadn't been taking prescribed medications) and dosages adjusted for patients who were inadequately treated. Tell these patients to follow up with their healthcare provider or an outpatient clinic within a few days, as directed.4

A patient who comes to the ED with signs and symptoms of uncontrolled hypertension such as epistaxis may benefit from observation in the ED over several hours, an increase in current medications, or additional medication to further lower BP under observation and monitoring. When clinically stable, the patient may safely be sent home with oral agents and arrangements for follow-up in an outpatient setting.4

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What your patient needs to know

One of the greatest weapons you, as a nurse, can have against hypertensive crises is patient education. A patient like Mr. Ross needs to understand the disease process, his antihypertensive medications, and the consequences of abruptly discontinuing them or failing to take them as directed. Teach him how to monitor his BP at home, ensure he has the necessary equipment, and teach him when he needs to call his healthcare provider.

Encourage him to make these lifestyle modifications to manage hypertension and prevent another hypertensive crisis:1

* Lose weight if necessary. The patient should maintain a normal body weight, defined as a body mass index between 18.5 and 24.9 kg/m2. This can reduce systolic BP 5 to 20 mm Hg per 22 pounds (10 kg) of body weight.

* Adopt the Dietary Approaches to Stop Hypertension (DASH) eating plan. A diet low in fat and rich in fruits, vegetables, and low-fat dairy products can shave 8 to 14 mm Hg off systolic BP. For more on the DASH plan, visit http://www.nhlbi.nih.gov/health/public/heart/hbp/dash/new_dash.pdf.

* Reduce dietary sodium intake. Eating no more than 100 mmol/day (2.4 grams of sodium or 6 grams of sodium chloride) can reduce systolic BP by 2 to 8 mm Hg.

* Exercise. Regular aerobic activity, such as walking briskly for 30 minutes per day on most days of the week, can reduce systolic BP by 4 to 9 mm Hg.

* Stop smoking. Nicotine constricts blood vessels, raising BP.

* Limit alcohol consumption. Men shouldn't drink more than two alcohol drinks per day. Women and small men should avoid drinking more than one. (Examples of one drink are 12 ounces of beer, 5 ounces of wine, or 1½ ounces of 80-proof whiskey.) Moderation here can reduce systolic BP 2 to 4 mm Hg.

Consider the patient's ability to adhere to the treatment regimen and whether his age, financial status, and literacy level affect this. Address these issues as appropriate, depending on the cause.

You can participate in community-based screenings to identify people with undiagnosed hypertension and help educate them. Teach them how to identify signs and symptoms of impending hypertensive crises, such as the signs and symptoms of a stroke or MI. Emphasize the importance of continued follow-up treatment and adherence to the treatment regimen.

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Patients like Mr. Ross can have varied reasons for not adhering to treatment. Some patients don't understand the treatment or the reason for treatment, can't afford the medications, or feel that they don't have time to exercise or time and money to prepare a healthful diet. Others may have no signs and symptoms and don't think they have a problem. Explain the disease process and treatment to the Rosses in terms that they can understand, answer any questions they may have, and provide handouts for them to take home. Tell Mr. Ross about lifestyle changes that are within his control, such as regular exercise and a healthful diet. Making these changes can give him a sense of control over his health. Encourage him to follow up with his healthcare provider regularly for BP monitoring and medication management.

By teaching patients about hypertensive crisis and how to take charge of managing hypertension, you can help patients like Mr. Ross avoid repeated urgent visits to the ED.

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About hypertension

Risk factors for hypertension include:

* family history

* older age

* African-American race

* male sex

* smoking

* obesity

* insulin resistance and metabolic abnormalities

* high sodium intake

* excessive alcohol consumption.

Primary or essential hypertension, which represents 95% of all cases, is chronic BP elevation in the absence of other disease. Secondary hypertension is caused by another disease.

About 73 million Americans age 20 and older have hypertension, with a higher prevalence among African-Americans and older adults.1

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Stages of hypertension

The JNC 7 classifies BP as:

* normal—systolic BP under 120 mm Hg and diastolic under 80 mm Hg

* prehypertension—systolic BP between 120 and 139 mm Hg or diastolic between 80 and 89 mm Hg

* stage 1 hypertension—systolic BP between 140 and 159 mm Hg or diastolic between 90 and 99 mm Hg

* stage 2 hypertension—systolic BP of 160 mm Hg or more or diastolic of 100 mm Hg or more.

About 30% of patients with hypertension are unaware that they have this condition, and more than 40% of those diagnosed aren't treated. Of those treated, two-thirds don't have their BP controlled to under 140/90. Patients with hypertension are at greater risk for stroke, myocardial infarction, end-stage renal disease, peripheral vascular disease, coronary heart disease, and heart failure.1

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REFERENCES

1. The Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC7). NIH Publication No. 04-5230. Bethesda, MD: National Heart, Lung, and Blood Institute, Health Information Center, 2003. http://www.nhlbi.nih.gov/guidelines/hypertension.

2. Vaidya CK, Ouellette JR. Hypertensive urgency and emergency. Hospital Physician. 2007;43(3):43–50.

3. Varon J. Treatment of acute severe hypertension: current and newer agents. Drugs. 2008;68(3):283–297.

4. Vidt D. Hypertensive crises: Emergencies and urgencies. Cleveland Clinic, 2006. http://www.clevelandclinicmeded.com/diseasemanagement/nephrology/crises/crises.htm.

5. Marik PE, Varon J. Hypertensive crises: challenges and management. Chest. 2007;131(6):1949–1962.

6. Aggarwal M, Khan IA. Hypertensive crisis: hypertensive emergencies and urgencies. Cardiol Clin. 2006;24(1):135–146.

© 2009 Lippincott Williams & Wilkins, Inc.

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