Direct Pulse Transit Time measurement from an electronic weighing scale

A novel method to measure Pulse Transit Time (PTT) from the force sensors of a modified electronic weighing scale is presented. The method relies on the relation between PTT and the interval between I and J waves of the ballistocardiogram (BCG). The IJ interval and the PTT derived from a carotid and a femoral pressure-pulse waveform were simultaneously obtained from three subjects during paced respiration, which induces periodic hemodynamic changes. The correlation between the IJ interval and this PTT is 0.69 and the difference between measurements is -5.2±16.4 ms, which are values similar to those of commercial devices based on more invasive methods that can be applied only to subjects in supine position. The simplicity of the method and the cost-effectiveness of the device to implement it offer new perspectives for the ambulatory assessment of arterial stiffness.