C2P: An Unobtrusive Smartwatch-Based Platform for Automatic Background Monitoring of Fatigue

Cardiopulmonary disease prognosis can achieve therapeutic edge if the disorders can be detected and attended to at an early stage. This work proposes 'Cardiopulmonary Care Platform (C2P)' which in its current initial phase, targets at subjects in the stage of Functional Capacity II as per the NYHA staging system by detecting physiological fatigue, and signs of dispnea and palpitation, using a smartwatch after the subject has undergone a spell of physically intensive activity. A novel and computationally efficient solution is devised to reconstruct breathing cycles from raw PPG signal recorded from the smartwatch, which enables the system to continuously monitor the subject's heart rate and breathing pattern online. The method achieves high accuracy when verified against a precalibrated flow-meter. Also a novel and an accurate up/down stairs detection algorithm using onboard atmospheric pressure sensor is discussed. We also present a study of physiological measurements like heart rate, breathing rate and breathing signal power as possible markers for fatigue.