Stroke Volume During Orthostatic Challenge: Comparison of Two Non-Invasive Methods.

摘要

Background: Real time non-invasive determination of stroke volume (SV) is important to astronaut orthostatic testing. We compared simultaneous estimates of SV calculated from peripheral pulse waveforms with a more conventional non-invasive technique. Methods: Ten men and nine women completed 12-min protocols. The relative change (%delta) in beat-to-beat SV was estimated non-invasively from changes in pulse waveforms measured by application of infrared finger photoplethysmography (IFP) and thoracic impedance cardiography (TIC). The %delta SV values were calculated from continuous measurements in the supine posture and over the first 10 s (T1), second 10 s (T2), and 3 min (T3) of 80 degrees head-up tilt (HUT).