[Blood pressure variability in the elderly]

In the elderly, the difference in blood pressure (BP) between the day and the night is less marked than in young subjects, but it is also more unstable and more sensitive to changes in position, meals, and physical activity. A deficient cardiac baroreflex appears to be involved in this phenomenon. Mayer's oscillation, usually considered to reflect sympathetic vascular activation, is not amplified by standing, but generates slower oscillations, at lower frequencies. The sensitivity of the cardiac baroreflex is inversely correlated with age, but, after the age of 60 years, the correlation with the level of systolic blood pressure (SBP) is greater than with age and accentuation of SBP is the main determinant in problems of postural hypotension. Hypertension and alterations in the afferent pathway of the baroreflex, adrenergic receptors, structure of the arterial wall, and intravascular volume appear to participate in the changes of blood pressure variability observed in the elderly.