QUANTITATIVE CHEST COMPUTED-TOMOGRAPHY AS A MEANS OF PREDICTING EXERCISE PERFORMANCE IN SEVERE EMPHYSEMA

Rationale and Objectives. We assessed the value of quantitative high-resolution computed tomography (CT) as a diagnostic and prognostic tool in smoking-related emphysema. Methods. We performed an inception cohort study of 14 patients referred with emphysema. The diagnosis of emphysema was based on a compatible history, physical examination, chest radiograph, CT scan of the lung, and pulmonary physiologic evaluation. Results. As a group, those who underwent exercise testing were hyperinflated (percentage predicted total lung capacity +/- standard error of the mean = 133 +/- 9%), and there was evidence of air trapping (percentage predicted respiratory volume = 318 I 31%) and airflow limitation (forced expiratory volume in 1 sec [FEV1] = 40 +/- 7%). The exercise performance of the group was severely limited (maximum achievable workload = 43 +/- 6%) and was characterized by prominent ventilatory, gas exchange, and pulmonary vascular abnormalities. The quantitative CT index was markedly elevated in all patients (76+/-9; n=14; normal < 4). There were correlations between this quantitative CT index and measures of airflow limitation (FEV1 r(2)=.34, p=.09; FEV1/forced vital capacity r(2) = .46, p = .04) and between maximum workload achieved (r(2) = .93, p = .0001) and maximum oxygen utilization (r(2)=.83, p=.0007). Conclusion. Quantitative chest CT assessment of disease severity is correlated with the degree of airflow limitation and exercise impairment in pulmonary emphysema.