System for contactless monitoring of tissue perfusion

The paper focuses on monitoring the cardiovascular system using photoplethysmography imaging. This technique allows the detection of slow and fast changes in skin blood perfusion. Based on the knowledge of previous studies, we present the customized design of the measurement setup, which consists of a light source, specific camera, and reference biosignal amplifier. Our measurement setup allows synchronous recording of image frames with reference signals, such as contact photoplethysmogram and respiration. These signals are an effective tool while handling the camera recorded data, which provide information about skin perfusion resulting from small color intensity changes in recorded images. The perfusion data are subsequently processed together with the synchronously measured contact photoplethysmogram. The algorithm calculates the cross-correlation function between the photoplethysmogram from the biosignal amplifier and signals extracted from recorded frames. We display results in color-coded maps containing the region of interest. The information derived from the measured data represents the blood volume changes. The main goal of the work is to prove the functionality of the proposed measuring setup.