Transfer factor for carbon monoxide: a glance behind the scene.
The transfer factor for carbon monoxide (TLCO) is widely used in pulmonary function laboratories because it represents a unique non-invasive window on pulmonary microcirculation. The TLCO is the product of two primary measurements, the alveolar volume (VA) and the CO transfer coefficient (KCO). This test is most informative when VA and KCO are examined, together with their product TLCO. In a normal lung, a low VA due to incomplete expansion is associated with an elevated KCO, resulting in a mildly reduced TLCO. Thus, in case of low VA, a seemingly "normal KCO" must be interpreted as an abnormal gas transfer. The most common clinical conditions associated with an abnormal TLCO are characterised by a limited number of patterns for VA and KCO: incomplete lung expansion, discrete loss of alveolar units, diffuse loss of alveolar units, emphysema, pulmonary vascular disorders, high pulmonary blood volume, alveolar haemorrhage.
Fitting
Jean-William
JW
Service de pneumologie, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland. jfitting@chuv.hospvd.ch
D000328:Adult; D000368:Aged; D000403:Airway Resistance / Q000502:physiology; D002248:Carbon Monoxide / Q000097:blood / Q000378:metabolism*; D005260:Female; D006801:Humans; D008171:Lung Diseases / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D011650:Pulmonary Alveoli / Q000473:pathology; D011652:Pulmonary Circulation / Q000502:physiology*; D011653:Pulmonary Diffusing Capacity / Q000502:physiology; D011659:Pulmonary Gas Exchange / Q000502:physiology*; D012129:Respiratory Function Tests; D012132:Respiratory Muscles / Q000473:pathology; D014109:Total Lung Capacity / Q000502:physiology
D002248:Carbon Monoxide