Influence of emphysema distribution on pulmonary function parameters in COPD patients

• Published in: Jornal brasileiro de pneumologia Vol. 41; no. 6; pp. 489 - 495
• Main Authors: Bastos, Helder Novais e, Neves, Inês, Redondo, Margarida, Cunha, Rui, Pereira, José Miguel, Magalhães, Adriana, Fernandes, Gabriela
• Format: Journal Article
• Language: English
• Published: Brazil Sociedade Brasileira de Pneumologia e Tisiologia 01-12-2015
• Subjects: Aged; Cross-Sectional Studies; Doença pulmonar obstrutiva crônica; Enfisema pulmonar; Female; Humans; Lung - pathology; Lung - physiopathology; Male; Original; Pulmonary Disease, Chronic Obstructive - diagnosis; Pulmonary Disease, Chronic Obstructive - pathology; Pulmonary Disease, Chronic Obstructive - physiopathology; Pulmonary Emphysema - diagnosis; Pulmonary Emphysema - pathology; Pulmonary Emphysema - physiopathology; Respiratory Function Tests; RESPIRATORY SYSTEM; Severity of Illness Index; Testes de função respiratória; Tomografia computadorizada por raios X; Tomography, X-Ray Computed; Doença pulmonar obstrutiva crônica; Pulmonary disease, chronic obstructive; Pulmonary emphysema; Tomography, X-ray computed; Testes de função respiratória; Enfisema pulmonar; Tomografia computadorizada por raios X; Respiratory function tests
• ISSN: 1806-3713; 1806-3756; 1806-3756; 1806-3713
• DOI: 10.1590/S1806-37562015000000136

To evaluate the impact that the distribution of emphysema has on clinical and functional severity in patients with COPD.
The distribution of the emphysema was analyzed in COPD patients, who were classified according to a 5-point visual classification system of lung CT findings. We assessed the influence of emphysema distribution type on the clinical and functional presentation of COPD. We also evaluated hypoxemia after the six-minute walk test (6MWT) and determined the six-minute walk distance (6MWD).
Eighty-six patients were included. The mean age was 65.2 ± 12.2 years, 91.9% were male, and all but one were smokers (mean smoking history, 62.7 ± 38.4 pack-years). The emphysema distribution was categorized as obviously upper lung-predominant (type 1), in 36.0% of the patients; slightly upper lung-predominant (type 2), in 25.6%; homogeneous between the upper and lower lung (type 3), in 16.3%; and slightly lower lung-predominant (type 4), in 22.1%. Type 2 emphysema distribution was associated with lower FEV1, FVC, FEV1/FVC ratio, and DLCO. In comparison with the type 1 patients, the type 4 patients were more likely to have an FEV1 < 65% of the predicted value (OR = 6.91, 95% CI: 1.43-33.45; p = 0.016), a 6MWD < 350 m (OR = 6.36, 95% CI: 1.26-32.18; p = 0.025), and post-6MWT hypoxemia (OR = 32.66, 95% CI: 3.26-326.84; p = 0.003). The type 3 patients had a higher RV/TLC ratio, although the difference was not significant.
The severity of COPD appears to be greater in type 4 patients, and type 3 patients tend to have greater hyperinflation. The distribution of emphysema could have a major impact on functional parameters and should be considered in the evaluation of COPD patients.