Vital Sign - PPG What does PPG mean?

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 level (SpO2) and is also a PPG. It can measure the change in the volume of arterial blood with each pulse beat. This change in blood volume can be detected in peripheral parts of the body such as the fingertip or ear lobe using a technique called photoplethysmography. The pulse oximeter that detects the signal is called a plethysmograph (or 'Pleth' for short).

Photoplethysmography (PPG) is used to estimate the skin blood flow using infrared light. Researchers from different domains of science have become increasingly interested in PPG because of its advantages as non-invasive and convenient diagnostic tool. PPG measures the oxygen saturation, blood pressure, cardiac output, and for assessing autonomic functions. Moreover, PPG is a promising technique for early screening of various atherosclerotic pathologies and could be helpful for regular general health assessment but a full understanding of the diagnostic value of the different features is still lacking.

The blood flow is normally shown as a waveform using a graph. It can provide useful information regarding the heart condition.