Fibrosing alveolitis in systemic sclerosis. Indices of lung function in relation to extent of disease on computed tomography

Abstract

Objective. Thin-section computed tomography (CT) provides a sensitive and reproducible method of quantifying the morphologic extent of disease in the clinical management of fibrosing alveolitis associated with systemic sclerosis (FASSc). The aim of this study was to determine which indices of lung function best reflect the extent of disease on CT in FASSc, and to determine the independent influences of smoking history, extent of fibrosing alveolitis, demographic features, and concurrent treatment upon functional impairment in FASSc.Methods. Sixty-four patients with FASSc were studied using CT and static and exercise lung function testing. Statistical relationships were determined by multiple regression analyses.Results. Five patients with overt pulmonary hypertension were characterized by severe impairment in 3 indices of lung function: diffusing capacity for carbon monoxide (DLco), DLco adjusted for alveolar volume (Kco), and arterial partial pressure of oxygen. On multiple regression analysis, the major determinant of functional impairment was the extent of fibrosing alveolitis on CT. A history of smoking was independently associated with preservation of total lung capacity and depression of Kco, but did not otherwise influence functional-morphologic correlations. The percent predicted DLco correlated better with extent of disease on CT (r = -0.70) than did oxygen desaturation on exercise (r = OSS), the physiologic component of the

Interstitial lung disease guideline

“…The evaluation of disease extent on HRCT allows global macroscopic morphological severity to be quantified, an advantage that is crucially lacking in biopsy evaluation. In patients with IIP136 and lung fibrosis in systemic sclerosis,137 disease extent on HRCT scanning correlates best with T lco , less well with maximal exercise data and poorly with lung volumes. Furthermore, T lco levels have been highly predictive of maximal exercise data in other studies 138 139.…”

“…T lco provides a stronger prediction of mortality28 506 507 and correlates better with the extent of disease on HRCT scans than other lung function variables 508…”

Serial Evaluation of High-Resolution Computed Tomography Findings in Patients with Idiopathic Pulmonary Fibrosis in Usual Interstitial Pneumonia

“…An earlier study by Wells et al [21]supports the rationale for applying a scoring system to HRCT findings. Among other things, their study demonstrated clear relationships between the extent of the disease and the severity of lung function impairment.…”

Monitoring of Lung Involvement in Rheumatologic Disease

“…In SSc, D LCO levels <40%, FVC levels <60% and a restrictive FEV 1 /FVC ratio are predictive of a marked increase in mortality [18,19]. In SSc, D LCO levels reflect the extent of disease on HRCT more accurately than lung volumes [20]. Thus, the identification of lung function trends that, if not addressed, will result in patients entering the high-risk groups above, is a major monitoring goal.…”

“…Right heart catheterisation is the reference standard in PH for the diagnosis, the definition of severity and the exclusion of left-sided heart disease [68] but is invasive and needs to be reserved for patients in whom PH is at least moderately probable. Pulmonary function profiles suggestive of supervening pulmonary vasculopathy include a disproportionate reduction in D LCO [69], reduced K CO [20] or increased FVC/D LCO ratio [70,71], severe resting hypoxia and arterial oxygen desaturation with minor exertion. The current European Society of Cardiology (ESC)/European Respiratory Society (ERS) guidelines recommend echocardiography in all CTD patients with pulmonary symptoms [68].…”