Peripheral Airspace Dimensions in Patients With COPD

Monodisperse aerosol particles can be used to assess noninvasively intrapulmonary airspace dimensions. Since emphysematic changes in the peripheral lung are difficult to detect with most of the common lung function tests, aerosol-derived airway morphometry was used to assess the peripheral airspace dimensions (EAD800) in 25 patients with COPD and in 36 healthy volunteers. Spirometric and body plethysmographic measurements were performed in all patients. In ten patients, high-resolution CT-derived mean lung density (MLD) was additionally assessed. In healthy subjects, EAD800 was 0.39±0.05 mm. In patients, EAD800 was significantly increased (0.82±0.33 mm). In a subset of nine patients with severe α1-antitrypsin deficiency and clinically severe emphysema, EAD800 was even larger (1.14±0.31 mm). In patients, EAD800 correlated with MLD (r=-0.82), diffusion capacity (Dco) (r=-0.78), and FEV1 (r=-0.75). Since MLD is considered a valid indicator for lung emphysema, the close correlation between EAD800 and MLD suggests that EAD800 reflects enlarged peripheral airspace dimensions in patients with emphysema.