Methods for diagnosing dysfunction of small airways and uniformity of lung ventilation: their use after a novel coronavirus infection

Abstract

In this lecture, we discussed methods and approaches to the diagnosis of small airways dysfunction, such as multiple breath nitrogen washout test, impulse oscillometry, as well as the calculation of poorly communicating fraction (PCF) as the ratio of total lung capacity to alveolar volume. The detection of the small airways dysfunction with the help of the diagnostic tools listed above makes it possible to establish functional disorders of the respiratory system in the early stages of bronchopulmonary diseases, when the results of traditional pulmonary functional tests remain within normal values. Thus, a well-standardized and the most accessible method for detecting the peripheral airways dysfunction is body plethysmography, which is used to diagnose the presence of “air trappings”. However, in the early stages of bronchopulmonary diseases, the possibilities of this method are limited. The lecture focuses primarily on the results of our own researches which were performed on patients who have suffered from a novel coronavirus infection complicated by viral pneumonia. Spirometry, body plethysmography, diffusion test, impulse oscillometry, multiple breath nitrogen washout test were conducted, and PCF index was calculated in all patients included in this analysis. The description of the PCF index, the method of its calculation, the range of normal values, as well as the possibilities of application in clinical practice are given for the first time in the Russian literature. The approaches to assessing the dysfunction of the small airways described in the lecture are not widely used at present, however, we hope that the knowledge that is currently being applied in scientific laboratories will gradually be introduced into routine clinical practice.