Diffusing Capacity

This test is used to assess the ability of the lungs to diffuse inhaled oxygen from the lungs into the bloodstream and is the most common test performed after spirometry. It is often performed in conjunction with spirometry and lung volumes as part of a Complex Lung Function Test.

This test involves the inhalation of a test gas which is held for 10 seconds then blown out. A sample of the exhaled test gas is collected and analysed and compared to your predicted values. A change in concentration of the test gas reflects how well your lung tissue (parenchyma) is able to deliver oxygen to the red blood cells in the bloodstream. You may be asked to have a blood test if your diffusing capacity is impaired to exclude anaemia.