Perfused lung volume to thoracic gas volume ratio (perfused lung fraction) in patients with COPD and in controls

BACKGROUNDThe deterioration of the ventilation-to-perfusion distribution in patients with chronic obstructive pulmonary disease (COPD) reflects structural changes affecting both the airways and the blood vessels. These changes result in lung perfusion abnormalities that may be quantified by lung perfusion single photon emission computed tomography (SPECT). OBJECTIVETo compare the perfused lung fraction (PLF) in patients with airflow obstruction and controls. METHODSFourteen patients with COPD and 21 controls underwent spirometry, whole-body plethysmography, and lung perfusion SPECT. PLF was derived from the ratio of perfused lung volume (measured by SPECT) to thoracic gas volume (measured by whole-body plethysmography). RESULTSIn the whole study sample, there were 18 (51%) women and 17 (49%) men, mean age was 46.2 (±20.3) years, range18–80 years). In the COPD group, PLF was 0.74 (±0.08), whereas in the control group PLF was 0.99 (±0.18) (P