Environmental Exposure, Airway Narrowing, Fibrotic Lung Injury: Multiscale Quantitative CT and CFD Analysis*

We investigated a physical mechanism underlying in the association between environmental exposure, airway narrowing, and lung injury. Chest computed tomography (CT) images at full inspiration and full expiration, pulmonary function tests, and exposure information were collected from toxic humidifier disinfectant (HD)-exposed normal-appearing adults (age=50±15, M:F=52:44) as well as normal-appearing adults (age=68±10, M:F=15:51) and idiopathic pulmonary fibrosis (IPF) patients (age=72±7, M:F=43:10) from an air pollution study. About 200 lung structure-function features of static lung and tidal breathing were computed from quantitative CT (QCT) analysis and three-dimensional (3D) and one-dimensional (1D) computational fluid dynamics (CFD) simulations. Lower lobe airway narrowing and associated increase in the workload of breathing were found in both HD-affected patients with normal appearing lungs and IPF patients with relatively high ambient exposure, particularly in the right lower lobe. Common findings in the two groups may suggest that inhalation of toxic environmental agents induces airway narrowing, and airway narrowing increases workload of breathing, even at decreased flow rate.