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Sarcoidosis, Spirometry, Obstruction
Background: Although sarcoidosis is commonly considered a restrictive disorder, more recent studies demonstrated opposite results. Objectives: To determine the prevalent functional pattern in patients with intrathoracic sarcoidosis and to assess the role of granulomatous inflammation in determining ventilatory disturbances. Methods: We included 144 consecutive newly diagnosed patients with sarcoidosis, who were evaluated by chest radiography, chest high resolution computer tomography, pulmonary function tests and dyspnea score. Additionally, endobronchial and transbronchial biopsies were performed to a subset of 78 patients. Results: We obtained a wide range of ventilatory abnormalities that characterize airways impairment: FEV1/FVC<70% - in 14 (9.7%) cases, low MMEF25-75 - in 69 (47.9%) patients, increased RV/TLC - in 65 (45.1%) subjects, while the subjects with restrictive defects was observed in a minority of cases - 7 (4.9%). Decreased DLCO was found in 100 (69.4%) individuals, in the majority of cases with mild changes. Patients in whom endobronchial biopsy showed granuloma had worse ventilatory results versus those in whom they have not been detected, with significant differences in FEV1 and MMEF25-75. We found significant correlations between radiological stage and pulmonary function tests. Dyspnea score (mMRC scale) in our cohort reflected lung volumes and DLCO modifications. Conclusion: The dominant functional abnormality in patients with intrathoracic sarcoidosis is obstruction, which affects the entire length of the bronchial tree causing a wide range of airways impairment and altered gas diffusion. These functional disturbances are prevalent from early stages of the disease and have a tendency to coexist with restriction as the disease advances. Granulomatous inflammation seems to have an important role in determining obstructive defect, even from “infra-radiological” stages.