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Lung diffusion test (DLCO)
DLCO · diffusion capacity test · gas transfer test · TLCO
You breathe in a safe gas mix and hold your breath for 10 seconds. The device shows how well your lungs pass gas into your blood.
For shortness of breath with no clear cause, for diseases of the lung tissue, to track treatment, or before some treatments.
⏱ Duration: usually 15 to 30 minutes; the report is usually ready the same day
Be sure to tell your doctor
How to prepare
- Smoking. Do not smoke on the test day, at least from the morning. Smoking changes the result a lot.
- Oxygen. If you use oxygen, say so in advance. They will tell you what to do.
- Food. A light breakfast. No hard exercise before the test.
What to bring
- Your referral
- A recent blood test, if you have one
- Past breathing tests
- A list of your medicines
How it goes
- You sit, and a clip is put on your nose
- You hold the tube with your lips and breathe calmly
- On command, you breathe all the way out
- You take a quick, deep breath of the gas mix
- You hold your breath for about 10 seconds
- You breathe out calmly. This is repeated 2 or 3 times with breaks
What you'll feel
- Holding your breath can be hard. Say so if you cannot manage
- The gas mix has no smell and is safe
Afterwards
- You can go back to your usual day right away
- The report is usually ready the same day
Common questions
Is the gas in the test dangerous?
No. There is very little of it, and you breathe it out quickly.
Why can't I smoke before the test?
Smoking changes your blood, and the test will look worse than it really is.