Postprandial reduction in blood pressure in the elderly.

We evaluated the effects of a meal on systolic blood pressure and heart rate in elderly institutionalized subjects (mean age +/- S.E.M., 87 +/- 1) with and without histories of syncope and in young normal subjects. Pulse and blood pressure were measured before the test meal and at intervals for up to 60 minutes afterward. By 35 minutes mean systolic blood pressure had declined a maximum of 25 +/- 5 mm Hg in 10 elderly subjects with syncope and 24 +/- 9 mm Hg in 10 elderly subjects without syncope (P less than 0.03); the level then stabilized without further change until 60 minutes. There were no changes in blood pressure in 11 young subjects or in elderly subjects not given a meal. The postprandial change in systolic pressure was not related to medications or diagnoses. Compensatory cardioacceleration was minimal in the elderly, suggesting impaired baroreflexes. Our observations show that postprandial reductions in blood pressure may predispose the elderly to symptomatic hypotension.