Assessment of autonomic nervous function in elderly subjects with or without postprandial hypotension

To examine the role of autonomic nervous dysfunction in postprandial hypotension (PPH) in elderly persons, we non-invasively assessed autonomic nervous function in 50 elderly subjects with or without PPH, defined as a reduction of more than 20 mmHg in systolic blood pressure (SBP) after a meal. The heart rate response to the reduction of SBP during head-up tilt was less and the coefficient of variation of R-R intervals was smaller in subjects with PPH than in those without PPH. The responses to cold pressor test, hyperventilation test, and mental arithmetic test were normal in all subjects. The magnitude of deltaSBP after meal ingestion closely correlated with deltaSBP during tilt-table examination, but did not correlate with the results of the cold pressor test, hyperventilation test, or mental arithmetic test. Stepwise multiple regression analysis revealed that the magnitude of the BP reduction and heart rate increase during the tilt-table test were independent predictors of the magnitude of deltaSBP after meal ingestion. The results indicate that impaired afferent pathways of baroreflexes, including baroreceptors, may play an important role in the pathogenesis of postprandial hypotension in the elderly and that the magnitude of the fall in SBP during tilt-table testing may be related to the degree of the postprandial reduction in BP in elderly persons.