Study of the functional residual capacity of the lungs caused by nitrogen leaching during multiple respirations and the diffusion capacity of the lungs in patients with bronchial asthma and chronic obstructive pulmonary disease

Relevance. This article discusses the use of nitrogen depletion and lung diffusivity measurements to assess functional lung capacity (FLC) in patients with bronchial asthma (BA) and chronic obstructive pulmonary disease (COPD).
Relevance. This article discusses the use of nitrogen depletion and lung diffusivity measurements to assess functional lung capacity (FLC) in patients with bronchial asthma (BA) and chronic obstructive pulmonary disease (COPD).
The purpose. Comparative assessment of FRC values measured using diffusion tests and nitrogen-leaching methods during multiple respirations.
Material and methods. An observational cross-sectional study was conducted. The examination results of the two groups were compared. Group 1: included 30 patients with BA of 3–4 severity — 13 men (43.4 %) and 17 women (56.6 %); the average age was 50.6±4.3 years at the stage of subsiding exacerbation. Group 2: included 30 patients with moderate COPD — 13 men (43.4 %) and 17 women (56.6 %), average age was 50.6±4.3 years. The functional residual capacity of the lungs was determined using the multiple-breath nitrogen washout method, whereas the diffusion capacity of the lungs. The statistical analysis and visualization of the obtained data were performed using the statistical computing environment R 4.3.0 (R Foundation for Statistical Computing, Vienna, Austria). Differences were considered statistically significant at a p<0.05. The Bland — Altman method was used to assess the consistency of the FRC measurements obtained from the two methods.
Results. Two groups of patients were examined: first group — 30 patients with BA of 3–4 severity; second group — 30 patients with COPD. When statistically analyzed between the two methods, no significant differences were observed in the FRC values using the nitrogen washout method and lung diffusivity. The Bland-Altman method produced similar statistical results.
Conclusion. Measurement of FRC in patients with asthma and COPD can be performed using both lung diffusivity and multibreath nitrogen washout methods.

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