Diffusion capacity

The diffusion capacity (DLCO) is used to determine the gas-transfer function of the lungs - whether gas can move from the air, across the interstitium, and into the blood. It is performed by having the patient breathe in a nonreactive gas, such as carbon monoxide (CO), which binds to hemoglobin. In order to reach the hemoglogin, the CO must diffuse across the alveolar-blood barrier. If there is thickening of the aleovli or interstitium, the diffusion will be impaired, resulting in a decreased DLCO. Therefore, the DLCO is useful in a patient with a restrictive disease, in order to determine if the restriction is intrinsic or extrinsic.
http://www.med.umich.edu/intmed/allergy/edu/syllabus/topics/...

一氧化碳弥散量（DLCO）
http://www.cqvip.com/QK/84051X/200905/32210738.html
http://www.dictall.com/indu59/77/5977865F44F.htm