Pulse oximeters work by shining two wavelengths of light, a red light and an infrared light, that pass through the skin of a finger. The device detects the color of blood, which differs depending on the amount of oxygen. Researchers suspect that the inaccurate readings may be occurring because of the way the light is absorbed by darker skin pigments. The study compared pulse oximeter measures with values obtained from a more invasive type of test, called an arterial blood gas test, carried out in the same patients at about the same time. Arterial blood gas tests are used more rarely, because they require drawing blood from an artery, which is a more invasive procedure than drawing blood from a vein.

Source: New York Times December 22, 2020 17:37 UTC