Hypertension is defined as an intermittent or sustained systolic BP of 140 mm Hg or higher or a diastolic BP of 90 mm Hg or higher. It occurs as essential, or primary, hypertension—in which no cause is identified—or as secondary hypertension—in which high BP is the result of a specific condition or medication. How does hypertension develop? What are its risk factors and signs and symptoms? What treatments are available? And what does your patient need to know after being diagnosed with hypertension? Let's take a closer look.
How it happens
Several theories exist as to how hypertension develops:
* changes in the arteriolar bed cause increased total peripheral resistance (TPR)
* abnormally increased tone in the sympathetic nervous system causes increased TPR
* increased arteriolar thickening caused by genetic factors leads to increased TPR
* abnormal renin release results in the formation of angiotensin II, which constricts the arterioles and increases blood volume (see Understanding hypertension).
Primary vs. secondary types
Ninety-five percent of hypertensive patients have primary hypertension. Risk factors include:
* advancing age
* diabetes (see Diabetes and hypertension)
* family history
* high intake of sodium, saturated fats, or alcohol
* sedentary lifestyle
Secondary hypertension may be caused by:
* adrenal gland tumor
* congenital narrowing (coarctation) of the aorta
* Cushing syndrome
* hyperaldosteronism (adrenal glands produce an excess of aldosterone)
* kidney disease (such as glomerulonephritis [inflammation of kidneys], renal failure, renal artery stenosis, and renal vascular obstruction)
* medications (such as appetite suppressants, certain cold medications, corticosteroids, migraine medications, and oral contraceptives)
* pregnancy (called gestational hypertension).
A person has prehypertension if he has a systolic BP between 120 and 139 mm Hg and a diastolic BP between 80 and 89 mm Hg. Obesity is a direct cause of prehypertension. Every 20/10 mm Hg increase in BP doubles the risk of myocardial infarction (MI), stroke, and renal disease. Prehypertension is also associated with narrowing of the carotid circulation and enlargement of the heart. One-third of prehypertensive individuals will develop hypertension within 4 years (see Classification of BP for adults ages 18 and older). Prehypertension is treated primarily with exercise and diet.
Hypertension is a direct cause of stroke and MI. It's directly linked to coronary artery disease, congestive heart failure, renal failure, and vision loss. Hypertension is also one of a cluster of conditions known as metabolic syndrome, or syndrome X, along with abdominal obesity, type 2 diabetes, insulin resistance, and high cholesterol and triglyceride levels.
Signs and symptoms of note
Often, a person with hypertension will have no symptoms. If present, signs and symptoms may include:
* blurred vision
* ear noise or buzzing
* irregular heartbeat
* papilledema (swelling of the optic disc).
Severe headache may be a sign of malignant hypertension—the sudden and rapid development of extremely high BP (diastolic reading as high as 130 mm Hg). Malignant hypertension is a medical emergency and requires hospitalization to bring the BP under control.
Getting to the heart of the matter
If your patient presents with high BP, you'll need to take a thorough health history and perform a physical exam. BP measurements should be repeated over time to confirm a diagnosis of hypertension. To measure BP, an upper arm cuff is recommended. Wrist cuffs have been criticized for potential inaccuracy due to disproportionate vasoconstriction in the distal arm; however, if a wrist cuff is used, your patient's wrist must be at heart level when the reading is taken. Remember to use the correct size cuff; a cuff that's too large for your patient's arm will register an artificially low reading.
Obtain a reading after your patient has rested for at least 5 minutes. He should be seated, with both feet on the floor and arms bared. There should be no talking and no arm movement. Ideally, your patient will have avoided caffeinated beverages and tobacco for at least 30 minutes before the reading. If possible, check the pressure in both arms. A difference of higher than 20 mm Hg will alert you to the possibility of vascular disease in the subclavian circulation and elsewhere.
Many patients have so-called white coat syndrome—becoming nervous when seeing a healthcare provider, which tends to cause an elevated BP. If this is the case with your patient, BP monitoring with a machine at home is an alternative. Home monitoring makes it possible to obtain a larger number of readings by following BP trends over the course of a given day. It can also be used to evaluate response to treatment.
Routine lab tests used to diagnose hypertension include urinalysis, sodium levels, potassium levels, creatinine, fasting blood glucose levels, and high-density lipoprotein cholesterol levels. An ECG may be ordered to assess for left ventricular hypertrophy. Creatinine clearance, renin levels, and a 24-hour urine protein may also be performed.
A risk factor assessment is needed to classify and guide the treatment of patients with hypertension who are at risk for cardiovascular damage, according to the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure, or JNC 7 (see Risk factors for cardiovascular problems in hypertensive patients).
The goal of hypertension treatment is to prevent complications by achieving and maintaining a BP of lower than 140/90 mm Hg (lower than 130/80 mm Hg for patients with diabetes or chronic kidney disease). Treatment begins with lifestyle modifications and continues with various medication regimens (see Hypertension treatment algorithm). Let's take a closer look.
Research demonstrates that regular physical activity, weight loss, and reduced sodium and alcohol intake are effective lifestyle modifications to reduce BP.
A minimum of 30 minutes of aerobic exercise, most days of the week, is recommended if not contraindicated. The patient should maintain a normal body weight. The goal for safe weight loss should be 1 to 2 pounds/week. Fad diets that promise to take off more than 2 pounds/week should be avoided because these diets are often low in nutritional value and can potentially cause additional health problems.
The patient should adopt the Dietary Approaches to Stop Hypertension (DASH) eating plan (see The DASH diet). The DASH plan recommends four servings of fruits and vegetables per day. These servings should be bought directly from the produce section because canned or frozen fruits and vegetables are high in sodium content. The DASH plan also recommends a diet low in saturated fat and cholesterol. Poultry and fish are lower in fat than beef. The exception to this is fried chicken, which is a high-cholesterol source, as are fast foods, cookies, and microwave popcorn. These sources of saturated fat raise levels of low-density lipoprotein (LDL) cholesterol, or bad cholesterol. Research has demonstrated that 2 months of the DASH diet can lower BP and LDL.
Adults in the United States consume 3 to 4 g of sodium a day. Sodium attracts water and raises BP. Sodium intake should be decreased to no more than 2 g/day. Only 10% of sodium intake comes from table salt and salt used in cooking, so the patient must read food labels to determine other sources. A low-sodium food should contain less than 140 mg/serving or less than 5% recommended daily allowance of sodium. Foods with more than 400 mg sodium/serving should be avoided. Sugar in the form of sucrose and fructose should also be limited because these can raise systolic BP and body weight.
The patient should limit alcohol consumption to no more than two drinks/day for men and no more than one drink/day for women. A drink is defined as 24 ounces of beer, 10 ounces of wine, or 3 ounces of spirits such as 80-proof whiskey. Patients should also avoid tobacco use because tobacco is a potent vasoconstrictor.
Most patients need at least two medications for adequate BP control (see Medications used to treat hypertension). For patients with uncomplicated hypertension, the recommended initial medications include diuretics, beta-blockers, or both. Medications are first given in low dosages. If BP doesn't fall to less than 140/90 mm Hg, the dosage is gradually increased and additional medications may be added to achieve control. To promote compliance, healthcare providers aim to prescribe the simplest treatment regimen possible, ideally one pill once a day. However, elderly patients, those with multiple diagnoses, and those with stage 2 hypertension (BP higher than 160/100 mm Hg) are especially difficult to treat. Healthcare providers are often concerned about overcorrection (making the patient hypotensive) and increased patient nonadherence to a complicated pill regimen.
Thiazide diuretics are often used as a first-line treatment. However, adverse reactions to these agents include increased LDL and uric acid levels, as well as increased insulin resistance. Loop diuretics may also be used.
Beta-blockers are frequently used as second-line agents. In low doses they can reduce catecholamine stimulation. Disadvantages include lack of efficacy in elderly patients and contraindication against use in patients with insulin-dependent diabetes or chronic obstructive pulmonary disease. Adverse reactions include an increase in lipid levels and insulin resistance.
Calcium channel blockers are an alternative for elderly patients and patients with diabetes who can't tolerate other drug types. These agents cause arterial dilatation and a decrease in cardiac output. Because they have long half-lives, calcium channel blockers are useful for once-a-day dosing. Patients shouldn't suddenly change brands because each formulation is very specific. Adverse reactions include palpitations, flushing, headache, and lower extremity edema.
Because most hypertensive patients have primary hypertension, in which the sympathetic and renin-angiotensin-aldosterone systems are hyperactive, angiotensin-converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs) can help reduce the vasoconstrictive action of angiotensin II. ACE inhibitors and ARBs are preferred for patients with diabetes, as they delay renal-heart disease. However, ACE inhibitors take 4 to 6 weeks to lower BP after treatment has begun. ARBs have been demonstrated to have 24-hour efficacy in treatment. Aldosterone receptor blockers may also be used.
Helping patients stay on track
Deviation from the therapeutic program is a significant problem for patients with hypertension. An estimated 50% of patients discontinue their medications within 1 year of beginning to take them. BP control is achieved by only 34% of hypertensive patients. Patient noncompliance is often due to adverse reactions of medications and lack of knowledge about the consequences of sustained hypertension. Patients complain about the cost of BP medications and the need to take them continuously, and often believe that the medications aren't really working. Other areas of concern are the low palatability of a low-sodium diet. Compliance increases when patients actively participate in self-care, including self-monitoring of BP and diet. Continued education and encouragement are usually needed to enable patients to formulate an acceptable plan that helps them live with their hypertension and adhere to the treatment plan. Compromises may have to be made about some aspects of therapy to achieve higher-priority goals.
The objective of nursing care for hypertensive patients focuses on lowering and controlling BP without adverse reactions and undue cost. To achieve these goals, you must support and teach your patient to adhere to the treatment regimen by implementing necessary lifestyle changes, taking medications as prescribed, and scheduling regular follow-up appointments with his healthcare provider to monitor progress or identify and treat any complications of disease or therapy. Your patient needs to understand the disease process and how lifestyle changes and medications can control hypertension. Emphasize the concept of controlling hypertension rather than curing it.
Encourage your patient to consult a dietitian to help develop a plan for weight loss if indicated. Explaining that it takes 2 to 3 months for the taste buds to adapt to changes in salt intake may help your patient adjust to reduced salt in his diet. Advise him to limit alcohol intake and avoid tobacco use. Support groups for weight control, smoking cessation, and stress reduction may be beneficial for some patients. Assist your patient to develop and adhere to an appropriate exercise regimen because regular physical activity is a significant factor in weight reduction and lowering BP. Also encourage your patient to monitor BP at home and teach him how to do so. Patients need to know that BP varies continuously and that the range within which their pressure varies should be monitored.
The American Heart Association and the National Heart, Lung, and Blood Institute provide printed and electronic patient education materials. Providing written information about the expected effects and adverse reactions of medications is important. Inform your patient that rebound hypertension can occur if antihypertensive medications are suddenly stopped. Also inform both female and male patients that some medications, such as beta-blockers, may cause sexual dysfunction; other medications are available if problems with sexual function or satisfaction occur.
Regular follow-up care is imperative so that the disease process can be assessed and treated. A history and physical exam should be completed at each clinic visit. The history should include all data pertaining to any potential problem, specifically medication-related problems such as postural hypotension.
The beat goes on
The pressure's on to reverse the global epidemic of this preventable condition. The bedside nurse is in the ideal position to encourage patients to adopt necessary lifestyle changes and to follow their prescribed medication regimen.
Diabetes and hypertension
No discussion of hypertension is complete without consideration of diabetes. One-half of patients with insulin-dependent diabetes also have hypertension, and only 10% of diabetic patients achieve adequate control of BP. Hypertension in patients with diabetes should be treated aggressively, with a BP goal of lower than 130/80 mm Hg. If renal disease is also present, the BP goal should be lower than 125/75 mm Hg to prevent further organ damage. Treatment goals for patients with diabetes and hypertension include regular self-monitoring of blood glucose levels and BP, taking medications as prescribed, reporting adverse reactions to the healthcare provider, and implementing strategies for stress reduction. With adequate control of BP, regression of left ventricular remodeling can be achieved in these patients.
Risk factors for cardiovascular problems in hypertensive patients
Major risk factors (in addition to hypertension)
* Dyslipidemia (elevated LDL [total] cholesterol and/or low HDL cholesterol)
* Diabetes mellitus
* Impaired renal function (glomerular filtration rate of less than 60 mL/minute and/or microalbuminuria)
* Obesity (body mass index higher than or equal to 30 kg/m2)
* Physical inactivity
* Age (older than age 55 for men, age 65 for women)
* Family history of cardiovascular disease (in a female relative younger than age 65 or male relative younger than age 55)
Target organ damage or clinical cardiovascular disease
* Heart disease (left ventricular hypertrophy, angina or previous MI, previous coronary revascularization, heart failure)
* Stroke or transient ischemic attack
* Chronic kidney disease
* Peripheral arterial disease
Source: National Heart, Lung, and Blood Institute. The Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure—Complete Report. http://www.nhlbi.nih.gov/guidelines/hypertension/jnc7full.pdf.
did you know?
According to a new Institute of Medicine report, public health policies should support healthier eating, reduced sodium consumption, and increased physical activity to curb the high rate of hypertension in the United States. Read the report at http://www.iom.edu/Reports/2010/A-Population-Based-Policy-and-Systems-Change-Approach-to-Prevent-and-Control-Hypertension.aspx.
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