reSPIRE: A wearable multimodal sensing system for monitoring ventilation, cardiovascular dynamics, and respiratory...

A properly functioning cardiopulmonary system is essential for sustaining life, but can be compromised by acute exacerbations of cardiopulmonary conditions or progressive declines caused by degenerative diseases. Continuous cardiopulmonary monitoring has been proposed to improve the treatment of such impairments by enhancing triage in acute settings and facilitating the early detection and ongoing management of progressive disorders. In spite of this, suitable monitoring technologies are scarce. Existing systems often provide only coarse indicators of cardiopulmonary status or are too obtrusive for continuous use. We present reSPIRE, a chest-worn sensing system that acquires (S)eismocardiography, (P)hotoplethysmography, (I)mpedance pneumography and cardiography, surface (R)espiratory mechanomyography and electromyography, and (E)lectrocardiography signals. We validated the system on healthy participants (n=18) with controlled breathing maneuvers, incremental inspiratory and expiratory loading, and stationary cycling. Strong correlations were observed between wearable-derived indices of respiratory muscle force and inspiratory mouth pressure (Spearman: ρ=0.87, repeated measures: r_rm=0.76). Significant phase-specific differences (p<0.001) in respiratory mechanomyography and electromyography band-powers were detected across both inspiratory and expiratory loading, leveraging respiratory phase context from the impedance pneuomgraphy signal. Tidal volume was accurately estimated from impedance pneumography, coefficient of determination (R²)=0.91, during sequences of spontaneous breathing and breathing while modulating rate and depth. Lastly, continuous tracking of hemodynamic (heart rate, pre-ejection period, impedance cardiography amplitude) and ventilatory changes was demonstrated throughout periods of cycling and recovery. These results demonstrate that the reSPIRE system's multimodal fusion enables precise monitoring of cardiopulmonary markers, advancing wearable-based monitoring and supporting its use in research of cardiopulmonary health.