Development of a condition monitoring system using an air-pack type pressure sensor for bedridden patients in a supine position

This paper proposes an online biological signal measurement system with an air-pack-type pressure sensor (APS) to monitor the condition of supine patients from pulse activity. The system enables estimation of three physiological signals corresponding to pulse pressure waves, pulse beats and respiratory waves from measurements taken and filtered using the APS, which has mechanical characteristics similar to the impedance characteristics of human muscle and can also be fitted with a mattress pad to prevent decubitus. In this study, the physiological significance of signals obtained through the APS was determined by comparing them with signals measured using commercial medical devices. The results showed that the correlations of pulse pressure waves, pulse beats and power spectral densities for respiratory waves between signals measured using the APS and those measured using commercial sensors were 0.84, 0.84 and 0.98, respectively. It was therefore concluded that the proposed system is suitable for outputting pulse pressure waves, pulse beats and respiratory waves.