Aims: This study aimed to design, develop, and assess a noninvasive affordable cardiac output (CO) trend monitor intended for telemedicine applications. An approach that will widely increase the availability of CO measurements, currently only available through expensive hospital equipment. This work will enable easy-to-access monitoring of heart failure diseases and their early detection, which will increase the quality of patient care, and reduce associated costs.
Methods: The estimation method of the CO trend is based on the transient analysis of a PPG (photoplethysmography) signal during venous occlusion. The PPG signal is acquired with an LED and photodiode, whereas a pneumatic inflatable 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 integrated into a portable device with wireless communications so it can be suitable for telemedicine applications. Some preliminary experiments were conducted on 4 healthy individuals. For each individual four different measures were taken at different times of the day, several days per week for four weeks. A more comprehensive study will be undertaken in the next few months in collaboration with the Virgen de la Arrixaca Hospital in Murcia simultaneously comparing the presented CO monitor with reference medical-grade equipment, including patients with varied heart conditions.
Results: The CO trend consistently reflected the daily CO variation patterns and events such as recent caffeine intake for certain individuals, and mild physical activities. Measured values changed up/down to 3 times its normal value.
Conclusions: The results show the proposed monitor can be used to determine sudden CO changes or to analyze CO trends changes with measurements taken over multiple days. All components have been integrated into a portable device with wireless communications for telemedicine applications.