Pulse Oximeter is a non-invasive medical device that checks the level of oxygen in a patient’s bloodstream and sounds an alarm as soon as it detects the slightest unsafe change. A small probe, attached to a separate computerized unit, is clipped to a spot on the body with good blood flow – typically the finger or the earlobe. Inside the probe is a light emitter that sends out two streams of light: one red and one infrared. Opposite the emitter is a photodetector which receives and measures these streams of light as they pass through.
Oxygenated haemoglobin absorbs a greater amount of infrared light while allowing more red light to pass through. Deoxygenated haemoglobin absorbs a greater amount of red light while allowing more infrared light to pass through. By calculating the absorption by haemoglobin in the patient’s blood stream at these two different wavelengths, the oximeter can calculate the level of oxygenation present.
The oximeter sounds a warning alarm as soon as it detects any change in the level of oxygen of patients under anaesthesia. Brain damage and heart failure can occur after as little as three minutes of oxygen starvation, and so early detection is critical.