Sunday, January 15, 2006

hypotension, orthostatic

Orthostatic hypotension is a fall in the arterial blood pressure when the person moves to a more upright position. Orthostatic blood pressure instability is common in the elderly. It should be suspected in people who become faint or experience dizziness when rising from a chair or bed. Many falls of the elderly can be traced to orthostatic hypotension. Symptoms include light headedness, blurring of vision, and a sense of weakness and unsteadiness. The two major causes of this disorder are depletion of the total blood volume and impairment of autonomic cardiovascular reflex activity. Both of these causes may coexist. Treatment of chronic orthostatic hypotension involves three basic methods: mechanical maneuvers, volume expanders, and pharmacologic agents. Mechanical measures include elevation of the head while resting, wearing a lower body compression garment, and exercises such as calf-muscle flexing. Patients should be taught to rise slowly and to remain as mobile as possible. Volume expanders include a high-salt diet and fluorocortisone acetate, which causes a uniform expansion of plasma volume. This expansion does not persist permanently in all patients. There are several pharmacologic agents used either alone or in sequence for the treatment of orthostatic hypotension. These drugs may include sympathomimetics, vasoconstrictors, Beta-receptor blockers, Alpha-receptor agonists, prostaglandin synthesis inhibitors, and antiserotonergics. These drugs mimic the actual effect of the body's natural vasopressors, although no single agent is uniformly successful.
Hurst, J. W. The Heart, 6th ed. St. Louis: McGraw-Hill Book Co., 1986.
Schatz, I. J. Orthostatic Hypotension. Philadelphia: F. A. Davis Co., 1986.

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