What is a blood gas test?
A blood gas test is used to accurately measure how much oxygen and carbon dioxide there is in your blood.
What is a blood gas test used for?
A blood gas test is used to check how well your lungs are working and whether they’re able to exchange oxygen and carbon dioxide properly.
It can be used to see if you need oxygen therapy.
What happens during a blood gas test?
Your doctor will take a small sample of your blood using a small needle and a syringe in your wrist. This is called an arterial blood gas.
The test can be painful, but your healthcare professional will do their best to reduce any discomfort. Sometimes, they will use local anaesthetic so you’ll not feel the needle.
Sometimes your blood gas will be tested by taking a blood sample from your earlobe. This is called a capillary blood gas.
During a capillary blood gas test, your healthcare professional will put some cream on your earlobe to help increase your blood flow. This makes your ear go red and feel hot.
After a few minutes your doctor can take a sample by pricking your earlobe and collecting the blood droplets. This is not painful, it’s similar to the way blood sugar levels are checked from a pinprick on your fingertip.
A capillary blood gas test normally cannot be used if you need to have the test when you are unwell. For example, if you’re admitted to hospital with a flare-up of COPD symptoms, you will not have a blood sample taken from your earlobe.
What do the results mean?
The results will be show:
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the level of oxygen in your blood
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the level of carbon dioxide in your blood
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how acidic or alkaline your blood is (pH).
The results will tell your healthcare professional if your body is getting enough oxygen. They also show if it’s removing enough carbon dioxide. If you’re not removing enough carbon dioxide, your blood will be more acidic. Your healthcare professional will explain your results to you.
A high level of carbon dioxide may mean that your breathing is shallow at night, and you may benefit from using a breathing machine, called a ventilator, at home.
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