Chest-accelerometry for hemodynamic trending during valsalva-recovery

Chest-worn accelerometers have been shown to detect acoustic and mechanical signals corresponding to cardiovascular activity. This paper aims at investigating and characterizing two different components of chest acceleration (seismocardiogram) along two orthogonal axes: firstly, the sub-10 Hz ballistic signal components dominant in the vertical axis and secondly, the 10-50 Hz acoustic signal components more dominantly expressed in the radial axis. Acceleration signals from five subjects in response to a valsalva maneuver were measured. Correlations of features from the two above acceleration components were computed with respect to reference measurements of stroke volume and pulse pressure obtained with a Finapres continuous blood pressure system. The peak amplitude of the vertical ballistic and radial acoustic signal components were found to correlate well with stroke volume (R=0.78 and 0.83, for vertical ballistic and radial acoustic, respectively). Comparable correlations were found between beat RMS power (R=0.77 and 0.83) and stroke volume. Similarly, correlations were also observed between pulse pressure and peak amplitude (R=0.74 and 0.86) and the beat RMS power (R=0.74 and 0.86).