Diffusing capacity of lungs in chronic obstructive pulmonary disease: gender, age, and race aspects

Introduction. Diffusion capacity of lungs is the second most important respiratory test after spirometry. The importance of assessing lung diffusion capacity in chronic obstructive pulmonary disease (COPD) is not given due attention, although this parameter reflects changes in functional lung volume and gas transport through the alveolar-capillary membrane, thereby providing more information about respiratory physiology than spirometry results. Diffusing capacity of the lung for carbon monoxide (DLCO) measurement is the standard in pulmonology, however, in recent years, close attention has been given to the determination of lung diffusion capacity for nitric oxide (DLNO), which gives better explanation of gas transport through the alveolar-capillary membrane compared to DLCO. Recent literature is actively discussing the inclusion of age, race, and gender aspects in spirometric reference equations that are used to assess spirometric parameters and lung diffusion capacity.Aim. To analyze the literature over the past five years, reflecting the views of modern researchers on methods for diagnosing lung diffusion capacity, as well as the contribution of age, race, and gender aspects to the assessment of this parameter in COPD.Materials and methods. The PubMed database was searched for information for the period 2017-2022 according to the selected inclusion criteria. Information requests included the following set of keywords: “diffusion capacity”, “chronic obstructive pulmonary disease”, “gender”, “age”, “race”, “DLNO”, “DLCO”. 123 articles were analyzed.Results. Recent evidence highlights the importance of including lung diffusivity in COPD prognostic programs. Determining the diffusion capacity of the lungs for nitric oxide may be a promising area of research soon. Gender and age considerations play an important role in the interpretation of spirometry data and lung diffusion capacity. The issue of including a racial trait in the assessment of the diffusing capacity of the lungs in COPD is in doubt.