[Role of emphysema in the etiology of functional impairment in patients with severe chronic obstructive pulmonary disease. Study with high resolution computerized tomography].
OBJECTIVE
To investigate whether high-resolution CT (HRCT) can detect the subjects with massive emphysematous destruction in a group of patients with severe chronic obstructive pulmonary disease (COPD) and therefore be of help in selecting the candidates to surgical lung volume reduction.


METHODS
We examined 40 former smokers with severe COPD (FEV1, < or = 40% of the predicted value, with no major improvement after inhalation of bronchodilators). Clinico-functional assessment included: a flow/volume loop (mean FEV1 = 28.6% of predicted), arterial blood gas analysis at rest breathing room air (mean values: PaO2 = 65.2 mmHg, PaCO2 = 47.4 mmHg), hematocrit value (mean: 45.2%) and the body mass index (mean value: 23.8). The patients were divided into two groups, namely bronchitic (21) and dyspneic (19) subjects, according to onset symptoms. All the patients underwent HRCT with evaluation of emphysema presence, type, site and extent: centrilobular emphysema was seen in 11 cases, panlobular emphysema in 3 and mixed emphysema in 26 cases; the site was superior in 75%, inferior in 7.5% and diffuse in 17.5% of cases; the mean visual score was 40.8%. The presence, type, site and severity of airways disease were also studied, as well as the pathologic dilatation of the pulmonary artery. The patients were divided into three groups (mild, moderate, severe) according to emphysema extent and they were considered to have bronchial disease in the presence of at least 2 of the 6 signs of bronchial involvement.


RESULTS
The emphysema extent score was significantly correlated with the hematocrit value and Tiffeneau index (p < .2) in all the 40 patients. The severity of bronchial obstruction was the same in bronchitic and dyspneic patients. The subjects with chronic bronchitis had milder emphysema (mean extent 35% versus 47% in the dyspneic subjects) and a higher frequency of bronchial involvement. A decrease in FEV1 was significantly correlated with emphysema extent (p < .1) in dyspneic, but not in bronchitic, patients. Moreover, the former had better arterial blood gas and lower hematocrit values.


CONCLUSIONS
HRCT is a useful tool in diagnosing the presence of emphysema in vivo and in assessing its extent in COPD patients because it permits to divide the patients into two groups which roughly correspond to the clinical patterns of types A (dyspneic) and B (bronchitic). Severe emphysema patients are the best candidates to surgical lung volume reduction. Airways involvement might play a major role in causing bronchial obstruction in the subjects with mild emphysema. In our series HRCT did assess the severity of emphysema in COPD subjects, but our lung function screening failed to predict emphysema extent.
D000368:Aged; D000369:Aged, 80 and over; D004646:Emphysema / Q000150:complications* / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D008173:Lung Diseases, Obstructive / Q000000981:diagnostic imaging* / Q000209:etiology*; D008297:Male; D008875:Middle Aged; D012720:Severity of Illness Index; D014057:Tomography, X-Ray Computed