Photoplethysmography (PPG)
What is photoplethysmography (PPG)?
Photoplethysmography (PPG) is an optical technique used to detect volumetric changes in the peripheral circulation of blood. It is both inexpensive and noninvasive, as it measures these changes at the skin’s surface.
PPG operates by using low-intensity infrared light, which is absorbed differently by skin pigments, bone, and blood as it passes through biological tissues. Blood absorbs infrared light more strongly than other tissues, so PPG sensors measure changes in light intensity to infer variations in blood flow. The voltage signal produced by PPG is proportional to the volume of blood flowing through the blood vessels.
While PPG cannot quantify the exact amount of blood flowing through the vessels, it is effective at detecting even small changes in blood volume.
Information that can be obtained through a PPG includes:
- Blood oxygen saturation
- Blood pressure
- Heart rate
- Cardiac output
- Endothelial function
- Arterial disease
- Venous assessment
- Vascular assessment
- Orthostasis
What are the applications of photoplethysmography (PPG)?
PPG technology is widely used in wearable medical devices to monitor various vital signs, such as blood oxygen saturation and heart rate, throughout the day. These wearable devices are valuable in telemedicine and remote monitoring, allowing healthcare providers to assess and track patients’ vital signs outside of traditional clinical settings.