Characterize Idiopathic Pulmonary Fibrosis Using Respiratory Oscillometry

Introduction: Idiopathic pulmonary fibrosis (IPF) is one of the most common forms of Intersitial Lung Disease. The degree of fibrosis may correlate with reduction in lung compliance. Patients are typically monitored with pulmonary function tests (PFTs), however, these are insensitive to peripheral airways dysfunction, provide limited information on lung compliance and airways resistance, and may be insensitive to detect disease progression. Respiratory oscillometry (Osc) performed during tidal breathing, measures total respiratory impedance, composed of resistance and reactance (X) at multiple wavelengths provides a comprehensive metric of respiratory mechanics and dynamic lung compliance. Objective: To characterize IPF using Osc. Methods: IPF patients identified in accordance with current ATS/ETS guidelines, were prospectively enrolled, assessed with paired Osc-PFTs, six-minute walk test (6MWT) and Quality of Life questionnaire. Results: Sixty-five patients (21F, 44M; mean age=71.3±7.9) were studied from Sept 2019-Jan 2020. PFTs data revealed (mean±SD):%FVC=70.5±16.2, %FEV1=75.4±17.0, %TLC=69.9±12.6, %RV=72.3±14.8, %DCO=61.3±18.7, %6MWT=106.0±22.0. Osc measurements were: AX=15.9±10.4, X5=3.6±1.2, Fres=21.2±4.9. Fres correlated with %FVC and %TLC (AIC=381 and 310, r2=0.19 and 0.16), respectively. %RV/TLC correlated highly with X5 (AIC=143, r2=0.23) and AX (AIC=392, r2=0.19). %Distance walked on 6MWT was mostly highly correlated with %DCO and %FVC (AIC=441 and 554, r2=0.38 and 0.16), respectively. Conclusions: Our preliminary findings suggest that Osc may provide information regarding IPF disease severity and used as an adjunct to PFT, particularly those who cannot tolerate spirometry and/or body plethysmography.