Design and developing a photoplethysmographic device dedicated to the evaluation of representative indexes in the response to vascular filling using systolic time intervals

Abstract

In this study, we develop an interface (human-machine) for monitoring the cardiovascular-respiratory system, through the evaluation of analogous indices obtained from a finger photoplethysmography pulse oximetry waveform. This interface consists of sensors, electronics associated with these sensors, acquisition card to make the communication with a local computer post and a graphical interface developed in visual basic environment for signals tracing and data archiving. In this work, we achieved the evaluation of representative indexes for the response to vascular filling, using systolic time intervals (STIs) namely, pre ejection period (PEP), respiratory change in pre ejection period (ΔPEP), left ventricular ejection time (LVET) and systolic time ratio (STR). Given that STIs, are highly correlated to the fundamental cardiac functions. In order to achieve this goal, a data collection study was conducted using synchronised acquisitions of electrocardiogram (ECG), photoplethysmogram (PPG) and pneumotachogram (PTG) signals.