Place de la distension pulmonaire dans l’exploration des gros fumeurs de cigarettes

Abstract

Lung hyperinflation (LH) has become a major concern in the management of chronic obstructive pulmonary disease (COPD). To evaluate the role of lung volumes in the positive diagnosis of COPD and in the assessment of airway obstruction reversibility. Three hundred and sixty-six male smokers over the age of 35 with more than 40 pack-years exposure were included in the study. Plethysmographic data were determined before/after taking a bronchodilator (BBD, ABD). Applied definitions: airflow obstruction: BBD FEV1/FVC<0.70. LH: BBD residual volume (RV)>upper limit of normal. Expressions of reversibility: Δvariable=(ABD-BBD) values; Δinit%=Δvariable/BBD value and Δref%=Δvariable/reference value. A 12%init and a 0.2L increase in either FEV1 or FVC or a 10%ref or - 300 mL decrease in RV were considered as clinically significant. Over the 85 smokers without airflow obstruction, 68% had LH. In the hyperinflated group (n=314), and compared to changes in FEV1 and FVC, these RV changes detected more respondents (54% for FEV1 and FVC vs. 65% for RV, P=0.002). This was not the case for the group free from LH (n=52) (23% for FEV1 and FVC vs. 35% for RV, P=0.09). In the 58 hyperinflated groups free from airflow obstruction, and compared to changes in FEV1 and FVC, changes in RV detected more respondents (24% for FEV1 and FVC vs. 71% for RV, P=0.0001). In heavy smokers, it seems essential to include LH as a criterion for a positive diagnosis of COPD and of reversibility evaluation.