Intra-individual variability in postural blood pressure in the elderly

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Abstract
Orthostatic hypotension, an age-related phenomenon, was associated with hypertension and body weight variability. To evaluate the relative contributions of blood pressure elevation and abnormalities in extracellular volume regulation to orthostatic hypotension, elderly institutionalized subjects (mean age = 87 .+-. 7 yr), taking no cardiovascular medications, underwent measurement of body weight (n = 15) and 1st morning supine and standing blood pressures (n = 19), 12-13 .times. per subject over a 2-4 wk period. There was a wide day-to-day variability in postural systolic blood pressure change (coefficient of variation = 533%) and a strong negative correlation between each day''s postural change in systolic blood pressure and basal supine blood pressure (r = 0.55, P < 0.0001). There was no association between postural blood pressure change and heart rate response or body weight changes, which were very small over the duration of the study (coefficient of variation = 0.6%). Elderly individuals have intact homeostatic mechanisms for the control of standing pressure when basal blood pressure is normal. Postural hypotension in the elderly is a variable phenomenon related to elevations in basal blood pressure.