Feature Article
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Orthostatic and Postprandial Hypotension Assessment and Management This article was adapted from a session at the 1999 American Geriatrics Society Annual Meeting.
Alterations in Blood Pressure Regulation Falls among older patients can result in significant morbidity and associated decreases in physical function. They also may result in death due to fractures, hemorrhage, and other injuries. It is therefore important to identify possible causes of falling, understand their precise mechanisms of action, and design treatments around those mechanisms. Hypotension (low blood pressure) is one such cause. Hypotension in the elderly patient can result in cerebral hypoperfusion, which in turn may lead to syncope (sudden loss of consciousness) and associated falls.
Hypotension in older individuals is a result of reduced systemic ability to regulate blood pressure. In addition to normal aging, age-related elevation in systolic blood pressure can impair regulation of blood pressure. Therefore, two principal factors leading to hypotension and ultimately to falls are age and systolic hypertension. The latter may be effectively treated, suggesting a possible strategy for treating hypertensive elderly patients suffering from hypotension-related syncope and falls.
Cardiovascular Changes in the Elderly A number of age-associated changes may be linked to the decreased ability of older patients to regulate blood pressure.1 Aging is associated with a decline in cerebral blood flow, meaning that any decline in blood pressure may reduce cerebral blood flow below the threshold for cerebral hypoperfusion. Aging is also associated with impairment of the baroreflex (the reflex that increases heart rate and vascular resistance in response to hypotensive stress). Moreover, aging is associated with reduced renal salt and water conservation, leading in turn to volume depletion, orthostatic hypotension, and syncope. Finally, the older heart becomes stiff and impaired in early diastolic ventricular filling. This makes the older person particularly vulnerable to preload reduction.
These factors all increase the vulnerability of older patients to hypotension. Hypertension superimposed on age further impairs each of these mechanisms. Consequently, hypertensive elderly patients exist in a precarious balance, unable to counterregulate minor changes in blood pressure, and thus are quite susceptible to hypotension. Studies show a tremendous variability in systolic blood pressure among elderly patients throughout a typical day, related to a variety of activities that reduce preload. Standing, eating a meal, and taking medications have all been observed to cause hypotensive responses.2 The older heart is simply unable to compensate for preload reduction and other stresses by increasing heart rate and cardiac output.
Orthostatic Hypotension Orthostatic hypotension, also called postural hypotension, is defined as a 20 mm Hg or greater decline in systolic BP, or a 10 mm Hg or greater decline in diastolic BP when changing posture (ie, sitting upright or standing); lightheadedness and fainting may result. The prevalence of orthostatic hypotension increases with age. However, data from the National Health and Nutrition Survey indicate that orthostatic hypotension is related to systolic hypertension. Indeed, among individuals with systolic blood pressure above 160, prevalence of orthostatic hypotension remains uniformly high regardless of age.3 This suggests that hypertension, rather than age, may be the principal factor underlying orthostatic hypotension.
Orthostatic hypotension is widespread and can be dangerous to the elderly patient. It appears to be an independent predictor of all-cause and cardiovascular mortality, as well as an indicator of physical frailty.4,5 Finally, orthostatic hypotension is associated with a twofold increase in subsequent falls among nursing home residents with previous falls.6 These risks are greatest for patients with multiple episodes, highlighting the need for periodic measurement of blood pressure to determine the possible presence of persistent orthostatic hypotension.
Postprandial Hypotension Postprandial hypotension is defined as a 20 mm Hg or greater decline in systolic blood pressure occurring within an hour of eating a meal. It is an often overlooked cause of syncope-related falls. Although postprandial and orthostatic hypotension frequently overlap in the same patient, they are distinct conditions and must be considered and treated differently.7
One study of patients with hypertension and postprandial hypotension showed that treatment with isosorbide or nicardipine, which reduced baseline blood pressure, resulted in a reduction in postprandial hypotension.8 Current research seems to indicate that the careful and judicious normalization of blood pressure might improve this condition in older patients.
Causes of Hypotension The principal causes of hypotension in the elderly may be considered in two groups.1 The first includes factors that lead to acute hypotension. Systemic causes—including dehydration, deconditioning, and adrenal insufficiency— fall into this category, as does the use of many medications (including but not limited to antipsychotics, tricyclic antidepressants, vasodilators, levodopa, and monoamine oxidase inhibitors).
The second group of causes of chronic orthostatic or postprandial hypotension are those that affect the nervous system. These can be divided into central nervous system (CNS) disorders and peripheral nervous system disorders, or autonomic neuropathies. The causes of the CNS conditions include Parkinson's disease, multiple strokes, myelopathy, and brain stem lesions. The causes of the autonomic neuropathies include diabetes, amyloidosis, tabes, alcohol, paraneoplastic syndromes, and a variety of nutritional problems.
Managing Blood Pressure Dysregulation in the Elderly The first step in the management of blood pressure dysregulation in the elderly is to establish the type and degree of the condition. Multiple blood pressure readings are obtained in the morning, with posture change, after meals, and after medications. These readings allow the physician to determine whether the patient displays persistent hypertension, postprandial hypotension, orthostatic hypotension, or some combination of the three. If repeated blood pressure measurements reveal persistent hypertension, the condition should be treated but watched closely for signs of developing hypotension.
Once a patient has been diagnosed with orthostatic or postprandial hypotension, he or she will need an evaluation of autonomic dysfunction. In the event that the condition is pathologic hypotension—a true dysautonomia—the course of treatment will involve support of blood pressure. If, however, the patient is found to have physiologic orthostatic hypotension (ie, related to aging or hypertension) then the physician should consider judicious treatment of hypertension while avoiding the use of medications just before meals (when they might have an additional hypotensive effect).
An evaluation of autonomic function includes orthostatic and postprandial blood pressure and heart rate measurements, a pharmacologic history, an assessment of fluid intake, mobility, and weight gain or loss. In addition, the clinician should look for common symptoms of autonomic dysfunction, including dry mouth, incontinence, impotence, and abnormal sweating. Specialized laboratory tests—including the "tilt test," carotid sinus massage, cold pressor test, sweat tests, and many others—are available for more precise diagnoses under special circumstances.
Treatment of hypotension in the elderly should begin with nonpharmacologic interventions when possible.9 Obviously, the elimination of drugs that may have a hypotensive effect from the patient's regimen is important and necessary. Waist-high graded compression stockings designed to encourage venous return are effective, as are nocturnal elevation of the head and liberalization of salt intake if patients do not have heart failure. Simply crossing one leg in front of the other may also relieve hypotension while standing. Lifestyle modifications can assist enormously in the management of hypotension. Among the behaviors to avoid include large, high-carbohydrate meals; Valsalva voiding (which occurs during constipation); and standing up to urinate. Walking exercise can transiently increase blood pressure after meals, ameliorating postprandial hypotension.
When all else fails, medications are available for those patients with very severe autonomic or hypotensive symptoms.9 Usually the mainstay of treatment for the primary care geriatrician is fludrocortisone. Dosage is gradually increased from 0.1 mg/day up to 1 mg/day; the onset of heart failure, hypokalemia, or supine hypertension must be closely monitored. A vasopressor called midodrine has been useful in some patients,10 whereas the drug somatostatin is effective in controlling postprandial hypotension but requires injections before meals. Caffeine therapy, 250 mg (2 cups) in the morning, is useful for some patients.
Summary Hypotension is an important, yet often overlooked, cause of falls and syncope. Therefore, all patients with falls or syncope should undergo careful blood pressure monitoring at the same time of day and under the same circumstances associated with the falling event. This can often be accomplished by lending patients an automatic blood pressure machine and giving them a spreadsheet indicating times to measure their blood pressure at home. If orthostatic or postprandial hypotension is discovered in a patient with hypertension, judicious antihypertensive therapy with a calcium channel blocker may be worthwhile. If hypotension worsens or is not associated with hypertension, the patient should be evaluated for causes of autonomic insufficiency and treated accordingly. It is hoped that by identifying and treating these prevalent geriatric syndromes, falls, syncope, and their life-threatening consequences can be prevented.
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References 1. Lipsitz LA. Orthostatic hypotension in the elderly. N Engl J Med 1989;321:952- 957.
2. Jonsson PV, Lipsitz LA, Kelley MM, Koestner JA. Hypotensive re- sponses to common daily activities in institutionalized elderly: A potential risk for recurrent falls. Arch Intern Med 1990;150:1518-1524.
3. Harris T, Lipsitz LA, Kleinman JC, Cornoni-Huntley J. Postural change in blood pressure associated with age and systolic blood pressure: The National Health and Nutrition Examination Survey II. J Gerontol 1991;46:M159-M163.
4. Rutan GH, Hermanson B, Bild DE, et al. Orthostatic hypotension in older adults: The Cardiovascular Health Study. Hypertension 1992;19(6):508-519.
5. Masaki KH, Schatz IJ, Burchfiel CM, et al. Orthostatic hypotension predicts mortality in elderly men: The Honolulu Heart Program. Circulation 1998;98:2290- 2295.
6. Ooi WL, Hossain M, Lipsitz LA. The association between orthostatic hypotension and recurrent falls in nursing home residents. Am J Med 2000;108:106-111.
7. Jansen RWMM, Kelley-Gagnon MM, Lipsitz LA. Intraindividual reproducibility of postprandial and orthostatic blood pressure changes in older nursing-home patients: Relationship with chronic use of cardiovascular medication. J Am Geriatr Soc 1996;44:383-389.
8. Connelly CM, Waksmonski C, Gagnon MM, Lipsitz LA. Effects of isosorbide dinitrate and nicardipine hydrochloride on postprandial blood pressure in elderly patients with stable angina pectoris or healed myocardial infarction. Am J Cardiol 1995;75:291-292.
9. Jansen RWMM, Lipsitz LA. Postprandial hypotension: Epidemiology, pathophysiology, and clinical management. Ann Intern Med 1995;122:286-295.
10. Low PA, Gilden JL, Freeman R, et al. Efficacy of midodrine vs placebo in neurogenic orthostatic hypotension: A randomized, double-blind multicenter study. JAMA 1997;277:1046-1051.
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Dr. Lipsitz is Physician-in-Chief, Vice-President of Medical Affairs, and the Usen Director of Medical Research at the Hebrew Rehabilitation Center, and Associate Professor of Medicine at Harvard Medical School, Boston, MA. Address for correspondence: Lewis A. Lipsitz, MD, Hebrew Rehabilitation Center for Aged, 1200 Centre Street, Roslindale, MA 02131.
Annals of Long-Term Care - ISSN: 1524-7929 - Volume 8 - Issue 04 - April 2000 |