Nitrogen leaching in multiple breathing and structural changes in the bronchopulmonary system in adult patients with cystic fibrosis

The aim of this work was to assess the functional and structural disorders of the bronchopulmonary system detected by high-resolution computed tomography (HRCT) in adult patients with cystic fibrosis (CF), and to determine the correlation between them. Methods . A cross-sectional study included patients with CF (n = 54: 20 male and 34 female; median age 25 years) and healthy volunteers (n = 32: 12 male, 20 female; median age 25 years). A complex study of the pulmonary function test (PFT) was carried out; it included spirometry, bodyplethysmography and measurement of the diffusing lung capacity for carbon monoxide (DLCO), nitrogen leaching in multiple respiration (NLMR) and HRCT. Dyspnea was assessed using the Modified Research Council Scale (mMRC). NLMR measurements were performed using the Easy-One Pro module, MBW (NDD Medizintechnik AG, Switzerland). Analysis of HRCT data according to the Bhalla classification was performed by two independent, experienced radiologists. Results . The mean value (± SD) of the forced expiratory volume for 1 second (FEV1) was 63 ± 26% of the proper value, forced vital capacity of the lungs (FVC) was 86 ± 20% of the proper value, the ratio of FEV1/FVC was 61 ± 15%; residual lung volume (RLV) was 220 ± 71% of the proper value, the ratio of RLV/ total lung capacity (TLC) was 48 ± 13%, intrathoracic gas volume was 150 ± 33% of the proper value, DLCO was 80 ± 16% of the proper value, lung clearance index (LCI) was 16.9 ± 5.0; moment ratio (MR2) was 54.7 ± 34.1. Bronchoectases with predominant lesions of > 9 segments and bronchial lesions from V generation and more distal were found in all patients. Peribronchial infiltration and mucoid plugs were also diagnosed in almost all patients (94 and 96%, respectively), while bronchogenic cysts or abscesses, atelectasis/consolidation, bullae or emphysema were rarely detected (in 30, 35, 20, and 17% of cases, respectively). The parameters of NLMR were statistically significantly correlated with both the PFT parameters and the HRTC data. Conclusion . In adult patients with CF, there is a significant unevenness of pulmonary ventilation, progressing as structural damage to the bronchopulmonary system increases and the PFT worsens. With a statistically significant increase in MR, the involvement of not only the central, but also peripheral airways in the pathological process is emphasized. It has been established that in adult CF patients there is a strong correlation between LCI and the severity of structural changes, detected by HRCT, comparable in strength and significance to FEV1.