Influence of age on the immediate cardiovascular response to orthostatic manoeuvre.

The dynamics of cardiovascular changes following standing up from the supine position were investigated in 41 healthy men aged 20-59 years, classified into three groups: (22-26 years, n = 14), (33-49 years, n = 13) and (51-59 years, n = 14). The protocols consisted of a sequence repeated twice lying down-standing up-lying down. The initial period supine was for 20 min and then the subjects remained in each position for 8 min. Stroke volume, cardiac output (CO), ejection time (ET), pre-ejection period and heart rate (HR) were continuously calculated using automated impedance cardiography and electrocardiography. Blood pressure was measured by the auscultation method. The patterns of HR and haemodynamic orthostatic response were shown to be highly reproducible. Most of the indices characterizing the amplitude and rate of cardiovascular changes following standing up showed a tendency towards attenuation with age. However, only the indices of HR, CO and ET responses correlated significantly with age. The strongest relationships with age were observed in the sudden increase in HR (r = -0.61, P < 0.01), the transient increase in CO (r = -0.45, P < 0.001), and the rapid decrease in ET (r = 0.42, P < 0.01) after standing up. A few indices of HR and haemodynamic response also showed weak correlations with the subjects' heights and body masses.