Measuring postural changes in blood pressure in the healthy elderly.

Abstract

Background The reproducibility of postural changes in blood pressure of a healthy elderly population determined using standard clinical measurements is not known. To assess the differences in reproducibility of postural changes in blood pressure in healthy elderly subjects 1 and 3 min after standing within a day and between visits spaced 6 weeks apart. Casual readings of blood pressures of supine and standing subjects were measured twice during the day by the same observer on two occasions 6 weeks apart using a semi-automatic syphgmomanometer. Twenty-two subjects with no known risk factors for orthostatic hypotension (13 men) aged 69+/-3 years (mean+/-SD) with a mean initial screening supine blood pressure of 153+/-19/88+/-11 mmHg were recruited. There were significant differences(P<0.001) between the postural changes both for systolic and for diastolic blood pressure between 1 and 3 min of standing, the largest falls occurring after 1 min of standing, though we found no variation between morning and afternoon measurements and between visits. The coefficients of reproducibility between visits for the postural changes in blood pressure after 1 and 3 min of standing were large both for systolic and for diastolic blood pressure, ranging from 9.8 to 29.3 mmHg. There was a consistent and significant difference between the postural changes in blood pressure after 1 and 3 min of standing for this healthy elderly population, but there was no significant difference between the postural changes in morning and afternoon measurements and between visits. This marked variability in the postural change in blood pressure with duration of standing must be taken into account when assessing the prevalence of orthostatic hypotension and the effects of treatment in patients with orthostatic falls in blood pressure.