[Forced oscillation technique in the diagnosis of fibrotic phenotype interstitial lung diseases]

To identify functional features in patients with interstitial lung diseases (ILD), depending on disease phenotypes, using the forced oscillation technique.

A single-center cross-sectional observational study was conducted on 68 patients with ILD (mean age 64 years, 70.6% women). The diagnoses were distributed as follows: idiopathic pulmonary fibrosis 17.7%, chronic hypersensitivity pneumonitis 44.1%, non-specific interstitial pneumonia 14.7%, unclassified ILD 23.5%. According to Tomographia Computata data, fibrotic changes were detected in 74.1% of patients. All patients underwent comprehensive pulmonary function testing, including spirometry, body plethysmography, measurement of diffusing capacity of the lungs, and oscillometry (forced oscillation technique).

The ΔX5 parameter was statistically significantly higher in patients with a fibrotic phenotype than in those without fibrosis [0.92 (0.06- 1.63) hPa×s/L vs 0.19 (-0.05-0.43) hPa×s/L; p=0.016]. Patients with fibrosis also had significantly lower for diffusing capacity of the lungs (45.5% vs 52% predicted; p=0.027) and CO diffusion capacity - Kco (73% vs 81.5% predicted; p=0.037) values. Independent predictors of the fibrotic phenotype were ΔX5 (odds ratio 6.386, 95% confidence interval 1.479-27.564; p=0.013) and Kco (odds ratio 0.929, 95% confidence interval 0.867-0.997; p=0.040). ROC analysis showed that the combination of ΔX5 and Kco parameters has high diagnostic value for detecting fibrosis (AUC 0.817; p<0.001).

The oscillometry parameter ΔX5 and the Kco index from diffusing capacity measurement are independent predictors of a fibrotic phenotype in patients with ILD. The combination of these functional parameters improves diagnostic capabilities for detecting fibrotic changes. The FOT method provides clinically important information in patients with ILD and restrictive impairment.