Improving the accuracy of proximal timing detection from ballistocardiogram signals using a high bandwidth force plate
Ballistocardiography (BCG) is a non-invasive measure of the reactionary forces of the body to cardiac ejection of blood into the vasculature. BCG signals are currently measured by modified weighing scales, chairs, beds, or wearable tri-axial accelerometers. In this work, we measure the BCG using a high bandwidth multicomponent force plate and compare the timing accuracy of our measured signals with a weighing scale BCG that we have developed and verified in prior studies. We also examine the signal-to-noise ratio (SNR) of BCG signals obtained with each of the two instruments. Our results indicate that the force plate BCG measurement provides more accurate timing information as it allows for more reliable prediction of the pre-ejection period (PEP) — the time the ventricles spend in isovolumetric contraction — than the scale BCG (r2=0.83 vs r2=0.73). The SNR comparison results were as follows: although the force plate BCG has a slightly better SNR, the improvement is not significant and we conclude that SNR is limited by motion artifacts rather than instrumentation.