Cardiovascular reflex tests. Assessment of age-adjusted normal range.

To assess the relationship between aging and autonomic control of heart rate and blood pressure, cardiovascular reflex tests were performed in 70 healthy volunteers in the age range 25-71 years. R-R interval variation, heart rate change with deep breathing, 30/15 ratio and blood pressure response to standing appeared significantly declining with age. For each test we calculated the P0.99 and P0.01 confidence limits for individual observations. On the other hand, Valsalva ratio and the blood pressure response to sustained handgrip appeared to be unrelated to age. These results suggest that there is an age-dependent degradation of the mechanisms involved in the cardiovascular reflexes. The assessment of age-adjusted normal values improves the criteria for delineating abnormal from normal results in individual testing of autonomic function.