Standing ballistocardiography measurements in microgravity

Area of Science:

• Biomedical Engineering
• Space Medicine
• Cardiovascular Physiology

Background:

• Hemodynamic monitoring is crucial for astronaut health during long space missions.
• Existing methods may face limitations in microgravity or confined spacecraft environments.
• Ballistocardiography (BCG) offers a non-invasive method for assessing cardiovascular function.

Purpose of the Study:

• To demonstrate the performance and practicality of a scale-based BCG system for astronaut hemodynamic monitoring.
• To evaluate the signal quality and robustness of the scale-based BCG compared to traditional methods.
• To assess the feasibility of using BCG for hemodynamic monitoring in fractional-g and microgravity environments.

Main Methods:

• A modified electronic weighing scale with foot bindings was developed to mechanically couple subjects.
• Scale-based and accelerometry-based free-floating BCG were measured in 10 subjects during parabolic flights (simulated microgravity).
• Scale-based microgravity BCG data were compared with ground-based (1 g) measurements.

Main Results:

• The scale-based BCG system achieved a signal-to-noise ratio (SNR) 2.1 times (6.3 dB) higher than the free-floating method.
• The scale-based approach proved robust and practical for hemodynamic monitoring in simulated microgravity.
• A consistent 38.7 ms reduction in the RJ interval was observed from ground to microgravity, indicating physiological changes.

Conclusions:

• The scale-based BCG system is a promising tool for reliable hemodynamic monitoring of astronauts in space.
• This technology is suitable for fractional-g environments and small spacecraft like the Orion capsule.
• Observed physiological changes in microgravity highlight the system's sensitivity to cardiovascular shifts.