Ambulatory cardiovascular monitoring

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A suite of ambulatory data acquisition devices will be acquired to study cardiovascular control under normal functions of daily life as well as in controlled laboratory conditions. With ambulatory monitors of arterial blood pressure, blood flow velocity and tissue oxygenation, we will initiate new research areas that expand on our existing expertise in studies of cardiovascular dynamics. The nature of the equipment also insures that it will be used in standard laboratory conditions as well as ambulatory investigations. We pioneered the use of ultrasound imaging and Doppler ultrasound blood flow velocity measurements to quantify whole leg or forearm muscle blood flow during rest to exercise transitions under controlled laboratory conditions. Now we propose developing techniques that will permit quantification of brain and muscle blood flow and tissue oxygenation along with continuous arterial blood pressure under dynamic conditions of daily life: rising from bed or a chair, standing, walking or climbing steps. We continue to conduct, under controlled conditions with tethered equipment, studies of transitions from supine rest (with or without prior bed rest or in astronauts returning from the International Space Station), and we know that the simple transition of supine to seated, or of seated to standing positions causes a transient drop in arterial blood pressure and cerebral blood flow velocity. What we do not yet know is what happens to blood pressure, brain blood flow velocity and oxygenation with normal transitions to activities of daily life. We will examine mechanisms responsible for low blood pressure on standing. We will examine changes in brain blood flow and oxygenation with activities of daily life with a focus on why regular exercise might increase brain blood flow potentially benefiting cognitive function in an aging population. Overall, these data will provide novel information on the inter-relationships between blood pressure, flow and oxygenation to the brain or exercising muscles.