Spirometry measures the amount of air and speed at which a person can exhale by letting him exhale into a mouthpiece connected to a recording device called a spirometer, while gas diffusion tests assess how well oxygen and other gases enter the bloodstream from the lungs, explains WebMD. Other lung function tests include body plethysmography and inhalation challenge tests.
Arterial blood gases is a gas diffusion test that measures the levels of oxygen and carbon dioxide in the bloodstream, reports WebMD. Another gas diffusion test is carbon monoxide diffusion capacity, which provides measurements of the ability of the lungs to deliver small amounts of carbon monoxide into the blood.
Doctors use body plethysmography to obtain measurements of a person's total lung capacity and residual volume, according to WebMD. They order inhalation challenge tests for patients experiencing asthma or wheezing to assess the response of their airways to certain substances.
Lung function tests allow doctors to examine the function and capacity of the lungs, particularly the amount of air the lungs can hold, the speed of breathing in and out of the lungs, and the ability of the lungs to deliver oxygen into the blood and remove carbon dioxide from it, states WebMD. They diagnose lung illnesses, determine the severity of lung issues and evaluate the efficacy of lung treatments through lung function tests.