[The importance of lung volumes in the investigation of heavy smokers]. / Place de la distension pulmonaire dans l'exploration des gros fumeurs de cigarettes.

ABSTRACT

INTRODUCTION: Lung hyperinflation (LH) has become a major concern in the management of chronic obstructive pulmonary disease (COPD). MAIN AIM: To evaluate the role of lung volumes in the positive diagnosis of COPD and in the assessment of airway obstruction reversibility. POPULATION AND METHODS: 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. RESULTS: 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). CONCLUSION: In heavy smokers, it seems essential to include LH as a criterion for a positive diagnosis of COPD and of reversibility evaluation.