Blood Flow Response in Healthy Seniors

FOR IMMEDIATE RELEASEContact: Donna Krupa: 703.527.7357Cell: 703.967.2751 or [email protected]

BLOOD FLOW RESPONSE IN HEALTHY SENIORSCerebral blood flow response to orthostatic stresscan be predicted in elderly patients.

October 11, 2001 - Bethesda, MD--Each month, the American Physiological Society (APS) spotlights recent research findings designed to improve human well being and understand human health. A summary of the peer-reviewed article noted below, which appears in a recent edition of The American Journal of Physiology-Regulatory, Integrative and Comparative Physiology, has such a focus. The Journal is one of 14 peer-reviewed journals comprised of approximately 3,800 articles that are published by the Society each year.

BLOOD FLOW RESPONSE IN HEALTHY SENIORSCerebral blood flow response to orthostatic stress can be predicted in elderly patients.

SummaryStudies using transfer function analyses have shown that the relationship between arterial pressure (AP) and transcranial Doppler-derived cerebral blood flow velocity (CBFV) oscillations during resting conditions can be used to predict the CBFV response to a sudden blood pressure reduction during leg-cuff deflation. This analytic approach may be particularly useful in elderly patients if it can identify those at risk of cerebral hypoperfusion during orthostatic hypotension.

In a study conducted by researchers at Boston University, Beth Israel Deaconess Medical Center, Harvard Medical School, and Hebrew Rehabilitation Center for Aged, the transfer function between resting AP and CBFV was computed, using the corresponding impulse-response function to predict the CBFV response to sudden pressure changes during standing. The results were then compared with the predicted and observed responses between groups of healthy young and healthy elderly subjects.

MethodologyAP and CBFV were measured in 10 healthy young and 10 healthy elderly subjects during five minutes of quiet sitting and one minute of active standing while breathing was paced at 0.25 Hz. Transfer functions between AP and CBFV changes during sitting were estimated from each full waveform in both low-frequency (LF) and heartbeat-frequency (HBF) ranges. The impulse-response function was used to compute changes in CBFV during posture change.

ResultsThe LF transfer function did not predict orthostatic changes in CBFV in either group, suggesting normal cerebral autoregulation. In the HBF range, the prediction was high in elderly but not young subjects.

ConclusionThus, rapidly acting regulatory mechanisms that reduce the transmission of beat-to-beat changes in AP to CBFV may be engaged during posture change in young but not elderly subjects.

Source The American Journal of Physiology-Regulatory, Integrative and Comparative Physiology, September 2001.

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The American Physiological Society (APS) was founded in 1887 to foster basic and applied science, much of it relating to human health. The Bethesda, MD-based Society has more than 10,000 members and publishes 3,800 articles in its 14 peer-reviewed journals every year.

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Editor's Note: For the full text of the summary cited above, or to set up an interview with one of the researchers, please contact Donna Krupa at 703.527.7357 (direct dial), 703.967.2751 (cell) or [email protected].