Calculation of blood pulse transit time from PPG

Abstract

Photo Plethysmograph (PPG) is an instrument that assists in monitoring the volumetric changes in our body. It uses LEDs and their corresponding sensors as pairs in retrieving information in the form of electrical signals (low in amplitude). These signals are amplified and processed using various filters to give the desired output. The blood pulse wave in the form of a voltage signal is derived at two points, one at FINGER and the other at WRIST. The time difference between two corresponding peaks gives us the PULSE TRANSIT TIME (PTT). This PTT has various clinical applications in assessing few vital parameters in an easy and non-invasive way.