Orthostatic hypotension [Postural hypotension]

In orthostatic hypotension, the patient's blood pressure drops 15 to 20 mm Hg or more—with or without an increase in the heart rate of at least 20 beats/minute—when he rises from a supine to a sitting or standing position. (Blood pressure should be measured 5 minutes after the patient has changed his position.) This common sign indicates failure of compensatory vasomotor responses to adjust to position changes. It's typically associated with light-headedness, syncope, or blurred vision and may occur in a hypotensive, normotensive, or hypertensive patient. Although commonly a nonpathologic sign in an elderly person, orthostatic hypotension may result from prolonged bed rest, fluid and electrolyte imbalance, endocrine or systemic disorders, and the effects of drugs.

To detect orthostatic hypotension, take and compare blood pressure readings with the patient supine, sitting, and then standing.

Action stat!

If you detect orthostatic hypotension, quickly check for tachycardia, altered level of consciousness (LOC), and pale, clammy skin. If these signs are present, suspect hypovolemic shock. Insert a large-bore I.V. catheter for fluid or blood replacement. Take the patient's vital signs every 15 minutes, and monitor his intake and output. Encourage bed rest until condition is stable.

History and physical examination

If the patient is in no danger, obtain a history. Ask the patient if he frequently experiences dizziness, weakness, or fainting when he stands. Also ask about associated symptoms, particularly fatigue, orthopnea, impotence, nausea, headaches, abdominal or chest discomfort, and GI bleeding. Then obtain a complete drug history.

Begin the physical examination by checking the patient's skin turgor. Palpate peripheral pulses and auscultate the heart and lungs. Finally, test muscle strength and observe the patient's gait for unsteadiness.

Medical causes

Adrenal insufficiency.Adrenal insufficiency typically begins insidiously, with progressively severe signs and symptoms. Orthostatic hypotension may be accompanied by fatigue, muscle weakness, poor coordination, anorexia, nausea and vomiting, fasting hypoglycemia, weight loss, abdominal pain, irritability, and a weak, irregular pulse. Another common feature is hyperpigmentation—bronze coloring of the skin—which is especially prominent on the face, lips, gums, tongue, buccal mucosa, elbows, palms, knuckles, waist, and knees. Diarrhea, constipation, a decreased libido, amenorrhea, and syncope may also occur along with enhanced taste, smell, and hearing and cravings for salty food.

Alcoholism.Chronic alcoholism can lead to the development of peripheral neuropathy, which can present as orthostatic hypotension. Impotence is also a major issue in these patients. Other symptoms include numbness, tingling, nausea, vomiting, changes in bowel habits, and bizarre behavior.

Amyloidosis.Orthostatic hypotension is commonly associated with amyloid infiltration of the autonomic nerves. Associated signs and symptoms vary widely and include angina, tachycardia, dyspnea, orthopnea, fatigue, and cough.

Hyperaldosteronism.Hyperaldosteronism typically produces orthostatic hypotension with sustained elevated blood pressure. Most other clinical effects of hyperaldosteronism result from hypokalemia, which increases neuromuscular irritability and produces muscle weakness, intermittent flaccid paralysis, fatigue, headache, paresthesia and, possibly, tetany with positive Trousseau's and Chvostek's signs. The patient may also exhibit vision disturbances, nocturia, polydipsia, and personality changes. Diabetes mellitus is a common finding.

Hyponatremia.With hyponatremia, orthostatic hypotension is typically accompanied by headache, profound thirst, tachycardia, nausea and vomiting, abdominal cramps, muscle twitching and weakness, fatigue, oliguria or anuria, cold clammy skin, poor skin turgor, irritability, seizures, and decreased LOC. Cyanosis, a thready pulse and, eventually, vasomotor collapse may occur with a severe sodium deficit. Common causes include adrenal insufficiency, hypothyroidism, syndrome of inappropriate antidiuretic hormone secretion, and the use of thiazide diuretics.

Hypovolemia.Mild to moderate hypovolemia may cause orthostatic hypotension associated with apathy, fatigue, muscle weakness, anorexia, nausea, and profound thirst. The patient may also develop dizziness, oliguria, sunken eyeballs, poor skin turgor, and dry mucous membranes.

Other causes

Drugs.Certain drugs may cause orthostatic hypotension by reducing circulating blood volume, causing blood vessel dilation, or depressing the sympathetic nervous system. These drugs include antihypertensives (especially guanethidine monosulfate and the initial dosage of prazosin hydrochloride), tricyclic antidepressants, phenothiazines, levodopa, nitrates, monoamine oxidase inhibitors, morphine, bretylium tosylate, and spinal anesthesia. Large doses of diuretics can also cause orthostatic hypotension.

Treatments.Orthostatic hypotension is commonly associated with prolonged bed rest (24 hours or longer). It may also result from sympathectomy, which disrupts normal vasoconstrictive mechanisms.

Nursing considerations

▪ Monitor intake and output and weigh the patient daily.

▪ Elevate the head of the bed, and help the patient to a sitting position with feet dangling over the side of the bed; if tolerated, have him sit in a chair for brief periods.

▪ Evaluate the patient's need for assistive devices, such as a cane or walker.

▪ Prepare the patient for diagnostic tests, such as hemoglobin level and hematocrit, serum electrolyte and drug levels, urinalysis, 12-lead electrocardiogram, and chest X-ray.

Patient teaching

▪ Advise the patient to change his position gradually.

▪ Show the patient how to use the call bell and tell him to call for assistance when getting out of bed or a chair.

▪ Explain the importance of maintaining an adequate fluid intake.

▪ Explain prescribed medications and their adverse effects.

Book Source Details

• Book Title: Nursing: Interpreting Signs and Symptoms
• Author(s): Springhouse
• Year of Publication: 2007
• Copyright Details: Nursing: Interpreting Signs and Symptoms, Copyright © 2007 Lippincott Williams & Wilkins.

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Copyright Details: Nursing: Interpreting Signs and Symptoms, Copyright © 2008 Williams & Wilkins.

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More About This Book: Title: Nursing: Interpreting Signs and Symptoms Authors: Springhouse Publisher: Lippincott Williams & Wilkins Copyright: 2007 ISBN: 1-58255-668-7

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