Reproducibility of circulatory changes to head-up tilt in healthy elderly subjects

OBJECTIVE: to assess the reproducibility of the cardiovascular responses to head-up tilt including cardiac output, stroke volume and peripheral resistance, in healthy older subjects using non-invasive methods. PARTICIPANTS: twenty-five healthy community-dwelling volunteers with a mean age of 69+/-3 years. METHODS: the subjects underwent head-up tilt table testing on two occasions at an interval of 6 weeks. Pulse interval and blood pressure data were collected, on a beat-to-beat basis using a non-invasive monitor (Finapres, Ohmeda), during 70 degrees head-up tilt table testing and stored for analysis. ANALYSIS: the pulse interval and blood pressure data for the group were pooled and the relative changes in cardiac output, stroke volume and peripheral resistance were calculated using pulse contour analysis. RESULTS: the systolic blood pressure, pulse interval, cardiac output and stroke volume fell immediately after tilt with a rise in peripheral resistance. These responses were similar, though the baseline systolic blood pressure levels were lower at the second visit (P=0.06). CONCLUSION: these non-invasively assessed cardiovascular responses to head-up tilt in healthy older subjects show little variation between visits. The reproducibility of the responses in subjects with syncope and autonomic failure warrants further investigation.