24/08/2015
https://www.amperordirect.com/pc/help-pulse-oximeter/z-what-is-oximeter-plethysmograph.html
A plethysmograph is an instrument for measuring changes in volume within an organ or whole body (usually resulting from fluctuations in the amount of blood or air it contains). A photoplethysmograph (PPG) is a plethysmograph that uses optical techniques. A pulse oximeter measures oxygen saturation l…