Cardiovascular Response to Orthostatic Fractional Gravity

There are no equivalent experiment setups to create comparable changes of gravitation such as during parabolic flights. To determine the initial orthostatic responses of the cardiovascular system under the gravitational conditions of mars and moon is an essential step for a better understanding of 1) the fundamental functions of the human cardiovascular system (basic research) 2) specific impact of partial-g on the human heart, lungs and vessels in a spaceflight-context 3) approaches for countermeasure development against orthostatic intolerance on moon and mars (applied research).

Non-invasive measurement methods will be used to achieve the cardiovascular key values of the study: stroke volume (SV) and cardiac output determination by pulse contour analysis, impedance cardiography and inert gas rebreathing, beat-to-beat finger blood pressure measurement, heart rate and heart rate variability determination by ECG. All of these methods have proven their accuracy during parabolic flights. Nevertheless pulse contour analysis and impedance cardiography are known to provide only relative SV and CO values. Thus inert gas rebreathing gives us the possibility to calibrate these stroke volumes and cardiac outputs to absolute values. Success of this procedure was shown during former parabolic flights.