THEORETICAL, METHODOLOGICAL AND CLINICAL ASPECTS OF STUDY OF LUNG DIFFUSION CAPACITY

Abstract

The study of lung diffusion capacity (or transfer factor (D_L), where D_L is a measure of the ability of the lungs to transfer oxygen from the alveolar gas into the blood) is one of the most important methods (the second after spirometry) to estimate the lung function. It is included in the standard medical examination of interstitial and disseminated lung diseases. The lecture discusses theoretical aspects of the gas exchange across the alveolar-capillary interface, describes in detail the methodology of the study of lung diffusion capacity for carbon monoxide by the single-breath technique, since this is the most common methodology used around the world, recommended by the American Thoracic Society (ATS) and the European Respiratory Society (ERS). In addition, the lecture discusses the main errors of single-breath maneuver technique, gives the scale of the severity of decrease in D_L, describes the main pathological processes that reduce the area of the diffusion surface or increase the diffusion distance by increasing the thickness of the alveolar-capillary membrane, and thus cause a lung diffusion capacity decrease, i.e. a reduction of transfer factor, as well as the list of conditions under which there is an increase of the transfer factor.