Lung diffusion testing

Alternative names:

diffusing capacity

How the test is performed:

You inhale a single breath from a volume of gas containing a known small quantity of carbon monoxide, hold your breath for 10 seconds, then rapidly exhale. The exhaled gas is then analyzed to determine the amount of carbon monoxide that was absorbed during the breath.

How to prepare for the test:

Do not eat a heavy meal before the test. Do not smoke for 4 to 6 hours prior to the test. Specific instructions will be given if bronchodilators or inhaler medications are to be withheld before the test.

Infants and children:
The physical and psychological preparation you can provide for this or any test or procedure depends on your child's age, interests, previous experience, and level of trust. For specific information regarding how you can prepare your child, see the following topics as they correspond to your child's age:

• infant test or procedure preparation (birth to 1 year)
• toddler test or procedure preparation (1 to 3 years)
• preschooler test or procedure preparation (3 to 6 years)
• schoolage test or procedure preparation (6 to 12 years)
• adolescent test or procedure preparation (12 to 18 years)

How the test will feel:

There is a tight fitting mouth piece to breathe through, and nose clips are applied.

Why the test is performed:

The test is performed to determine the presence and extent of certain lung diseases that affect how gases are diffused within the lung.