Lung Function Tests in Clinical Diagnosis of Pulmonary Emphysema

Pulmonary function studies were performed in 25 patients with pulmonary emphysema, diagnosed by clinical, roentgenographic and functional examinations. Lung function tests included spirometry, flow-volume curve, body plethysmography and single breathholding carbon monoxide transfer test. The spirometric ratio of forced expiratory to forced inspiratory volumes for the first 0.5 second (FEV0.5 /FIV0.5) was also calculated. Mean spirometric results, as the percentage of predicted, were: vital capacity (VC)=57.6%, forced expiratory volume in one second (FEV1)=30.0% and 100⋅FEV1/VC=37.2. The ratio FEV0.5/FIV0.5 was 0.39±0.14. The flow-volume curve showed low expiratory flows in all patients and collapsing shape in 20 out of 25 patients (80%). Body plethysmography revealed mean airway resistance (Raw)=0.54 kPa ⋅ l ⋅ s, thoracic gas volume (TGV)=218%, total lung capacity (TLC)=140.5%, and 100⋅RV/TLC=63.9. Transfer factor (TLCO) was 49±19.6%, and transfer coefficient (KCO) 47±21.1% of predicted. It is concluded that lung ventilation tests in pulmonary emphysema patients are characterised by severe obstructive ventilatory impairment, increased TLC, decreased pulmonary diffusing capacity and severe lung hyperinflation. Statistical analysis in this study shows that among ventilatory tests, the ratio FEV0.5/FIV0.5<0.62 (i.e. result below the statistical level of mean+1.64 SD, found in emphysema patients) is the best indicator of lung emphysema obtainable by routine spirometry, showing highly significant correlation with TLCO (r = 0.772; p<0.001) and KCO (r = 0.679; p<0.001). It is suggested that this ratio should be included in the computer program of routine spirometers.