Title :
Standing ballistocardiography measurements in microgravity
Author :
McCall, Corey ; Stuart, Zachary ; Wiard, Richard M. ; Inan, Omer T. ; Giovangrandi, Laurent ; Cuttino, Charles Marsh ; Kovacs, Gregory T. A.
Author_Institution :
Electr. Eng. Dept., Stanford Univ., Stanford, CA, USA
Abstract :
The performance and practicality of a scale-based ballistocardiogram (BCG) system for hemodynamic monitoring of astronauts on extended space missions was demonstrated. The system consists of a modified electronic weighing scale fitted with foot bindings to mechanically couple the subject to the scale. This system was tested on a recent series of parabolic flights in which scale-based and accelerometry-based free-floating BCG of 10 subjects was measured in microgravity. The signal-to-noise ratio (SNR) of the scale-based BCG was, on average, a factor of 2.1 (6.3 dB) higher than the free-floating method, suggesting that the tethered scale approach might be more robust in terms of signal quality. Additionally, this approach enables practical BCG-based hemodynamic monitoring in fractional-g environments, and on small space vehicles such as NASA´s upcoming Orion capsule. The scale-based results in microgravity were also compared to ground measurements (1g), where there was an average 38.7 ms RJ interval reduction from ground to microgravity environments that is consistent across 9 of 10 subjects. This phenomenon is likely due to the transient increase in venous return, and consequent decrease in pre-ejection period, experienced during the microgravity time intervals.
Keywords :
accelerometers; aerospace biophysics; blood flow measurement; cardiovascular system; medical signal processing; zero gravity experiments; BCG-based hemodynamic monitoring; NASA; Orion capsule; RJ interval reduction; SNR; accelerometry-based free-floating BCG; astronauts; extended space missions; foot bindings; fractional-g environments; free-floating method; ground environments; ground measurements; microgravity environments; microgravity time intervals; modified electronic weighing scale; parabolic flights; pre-ejection period; scale-based BCG; scale-based ballistocardiogram system; signal quality; signal-to-noise ratio; small space vehicles; standing ballistocardiography measurements; tethered scale approach; venous return; Band-pass filters; Electrocardiography; Extraterrestrial measurements; Hemodynamics; Monitoring; Signal to noise ratio; Timing;
Conference_Titel :
Engineering in Medicine and Biology Society (EMBC), 2014 36th Annual International Conference of the IEEE
Conference_Location :
Chicago, IL
DOI :
10.1109/EMBC.2014.6944792