A Noninvasive Cardiac Output Trend Monitor Targeting Telemedicine Applications

摘要

This study aimed to investigate and validate a noninvasive affordable cardiac output (CO) trend monitor intended for telemedicine applications. The approach of this work will widely increase the availability of CO measurements, currently only available through expensive hospital equipment. The estimation method of the CO trend is based on the transient analysis of a PPG (photoplethys-mography) signal during venous occlusion. The PPG signal is acquired with an LED and a photodiode as in typical pulse oximeters, whereas a pneumatic cuff and pressure pump implement the occlusion and release cycles. The CO trend is given by the relative comparison of different CO measurements of the same individual. All the components used in this work have been already integrated into a portable device with wireless communications so it can be suitable for telemedicine applications. Different measures were taken on different individuals at different times of the day, several days per week during some weeks. The CO trend consistently reflected the expected daily CO variation patterns and events such as food intake and mild physical activities. The proposed methodology can be used to determine sudden CO changes or to analyze the underlying overall CO trend with measurements taken over multiple days.