Avaliação das pequenas vias aéreas em pacientes com doença pulmonar obstrutiva crônica e deficiência de alfa-1 antitripsina

Abstract

The small airways have an internal diameter of less than 2 mm and are not evaluated by traditional pulmonary function tests. Thus, interest in the nitrogen washout test has increased. This study aimed to evaluate the small airways in COPD patients through a nitrogen washout test and to verify if there is a difference between patients with smoking COPD and COPD due to alpha-1 antitrypsin deficiency. It was contacted by telephone 582 patients from the COPD outclinic, and 61 were included in the study, 45 of whom had no mutation of the Serpina 1 gene and 16 with mutation, 5 of them with severe mutations. There were no differences in clinical and functional data (spirometry, pulmonary volumes, diffusion capacity) between the two groups, except for differences in smoking load, which was smaller in patients with mutation. The variables NΔ2 750-1250ml (%), Slope of phase III (%) and Closing capacity (%) of the nitrogen washout test were compared in these two groups with mutation (n = 16) and without mutation (n = 45) . The phase III slope and the ΔN2 750-1250mL (%) were able to predict levels of COPD severity as FEV1 (%). In addition, we found an inverse relationship between the smoking load and closing capacity (%) in the group of patients with COPD and mutation of the alpha 1 antitrypsin gene (p = 0.014). The small airways are of great importance in the genesis and development of lung diseases in general, especially COPD. This was the first study to evaluate the small airways through the nitrogen washout test in patients with mutation of the gene SERPINA 1. It was possible to observe a difference in ventilation heterogeneity by the washout test in COPD patients only due to smoking with COPD and alpha-1 antitrypsin deficiency.