Aerosol Morphometry and Aerosol Bolus Dispersion in Patients with CT-Determined Combined Pulmonary Emphysema and Lung Fibrosis

The simultaneous occurrence of pulmonary fibrosis and emphysema may present considerable problems in clinical assessment. Recent studies have shown that Aerosol Derived Airway Morphometry (ADAM) and Aerosol Bolus Dispersion (ABD) are changed in patients with pulmonary emphysema. This study was performed to assess the effect of simultaneous lung fibrosis in patients with emphysema on ADAM and ABD. ADAM and ABD measurements were performed in 20 patients with lone high resolution CT scan (HRCT) confirmed emphysema (E), and compared to those in 15 emphysematics with HRCT-confirmed superimposed pulmonary fibrosis (FE). In both groups the peripheral effective airspace dimension (EAD) (E: 0.63 ± 0.20 mm; FE: 0.60 ± 0.27 mm, N.S.) was increased by more than a factor of two compared to that of healthy subjects (0.28 ± 0.05 mm) (p < 0.001). Patients with E showed a significantly higher bolus dispersion than patients with FE (724 ± 122 cm3 vs. 546 ± 80 cm³; p < 0.001). However, in patients with FE, bolus dispersion was still significantly higher than in previously published control groups of healthy subjects (546 ± 80 cm³ vs. 455 ± 68 cm³; p < 0.001). The results of this study confirm that ADAM and ABD are powerful tools for identifying emphysema even in patients with superimposed pulmonary fibrosis.