Lung diffusion testing is designed to test how well your lungs allow oxygen and carbon dioxide to pass in and out of your blood. This process is called diffusion.
When you breathe, you inhale air containing oxygen through your nose and mouth. This air travels down your trachea, or windpipe, and into your lungs. Once in the lungs, the air travels through a series of increasingly smaller structures called bronchioles. It eventually reaches tiny sacs called alveoli.
From the alveoli, the oxygen from the air you breathe enters your blood in nearby blood vessels. This is a process called oxygen diffusion. Once your blood is oxygenated, it carries oxygen throughout your body.
Another form of diffusion occurs when blood containing carbon dioxide travels back to your lungs. The carbon dioxide moves from your blood to your alveoli. It’s then expelled through exhalation. This is a process called carbon dioxide diffusion.
Lung diffusion testing can be used to analyze both oxygen and carbon dioxide diffusion.