What is pulse oximetry?
Oxygen is carried around in your red blood cells by a molecule called haemoglobin. Pulse oximetry measures how much oxygen the haemoglobin in your blood is carrying. This is called ‘oxygen saturation’ and is a percentage (scored out of 100). It is an easy, painless measure of how well oxygen is being sent to parts of your body furthest from your heart, such as the arms and legs.
A device called a probe is placed on a body part, such as a finger or foot. The probe uses light to measure how much oxygen is in the blood.
How a pulse oximeter works
A pulse oximeter measures how much light is absorbed by your blood. This tells us how much oxygen your blood contains.
The pulse oximeter shines two lights through the skin: one red light and one infrared light.
Blood containing lots of oxygen absorbs more infrared light and lets more red light pass through it.
Blood without enough oxygen absorbs more red light and lets more infrared light pass through it.
If blood cells do not have enough oxygen, they will appear bluer.
What are the risks of pulse oximetry?
All procedures have some risks. The risks of this procedure may include:
- Incorrect reading if the probe falls off the foot
- Skin irritation from adhesive on the probe