Photoplethysmography as an Alternative to Impedance Cardiography-Based Hemodynamic Feature Point Detection

Cardiodynamic parameters, assessed by determining hemodynamic feature points are accessible by the impedance cardiography (ICG) technique. Classically acquired from the thorax, the shift to the peripheral locations like the wrist is anticipated during the progress of wearables. The interfered signal in the radial artery requires a revolution in applying ICG signal in an unconventional setting, which may be supported or even replaced by the photoplethysmography (PPG) technique. In this work, we propose a method relying on the fourth derivative of PPG to determine three cardiac markers for detecting the ICG-based hemodynamic feature points B, C, and X. The method is envisioned to enable more accurate and smart wearable device development for cardiovascular data acquisition.