Annual decline of lung function in pulmonary emphysema: influence of radiological distribution.

Fifty-six male patients with pulmonary emphysema and normal serum alpha 1-antitrypsin were followed for a minimum period of three years (range 3-13 yr) to observe the effects of the radiological distribution of emphysema on the annual rate of change of lung function indices. The subjects were placed in three categories--upper zone (UZ), lower zone (LZ), and generalised (G). The influence of smoking was taken into account with subjects in each radiographic category being divided into ex-smokers (group EX-S) and continuing smokers (group S). The rate of decline of FEV1, VC, TCO, and KCO was greater in group S than EX-S in all three x-ray categories. In group S, FEV1, VC, TCO, and KCO declined significantly faster in UZ emphysema than in G emphysema. In group EX-S, FEV1, TCO, and PaO2 declined significantly faster in UZ than G emphysema but VC remained unaltered. KCO and PaCO2 did not change significantly in any radiographic category in either group S or EX-S. Patients with G and LZ emphysema underwent very similar physiological changes over the course of time. Those with UZ emphysema, however, complained of exertional dyspnoea at an earlier age; a number of their lung function indices deteriorated at a faster rate than in patients from the other two categories, suggesting that UZ emphysema is a different disease entity.