Respiratory function in systemic sclerosis patients

Background: Pulmonary involvement is a prominent feature in systemic sclerosis (SSc) and a significant cause of morbidity and mortality. A restrictive ventilatory defect is typical and static lung volumes are usually reduced in patients with interstitial lung diseases. The possibility of obstruction of small airways in progressive SSc has been suggested by widespread bronchiolectasis and peribronchial fibrosis noted at necropsy. Objective: To study the functional properties of the respiratory system in SSc patients. Materials and Methods: 66 patients (9 M/57 F, mean age 51 ± 12 yrs.) suffering from limited (58%) and diffuse (42%) forms of systemic sclerosis were examined. Spirometry, body plethysmography and gas transfer test were performed. Results: Obstructive disorders were identified in 20 patients (30%), restrictive - in 11 (17%), mixed disorders - in 5 (8%). Lung function was normal in 30 (45%) patients. Diffusion capacity (DLco) was decreased in 54 (82%) SSc patients: 19 (35%) patients had mild (DLco = 60-80% of predicted.), 20 (37%) - a moderate degree (DLco = 40 -60% pred.), 15 (28%) - severe degree (DLco less than 40% predicted). DLco was normal in 12 (18%) patients. Functional markers VC, TLC, DLco were lower in patients with diffuse form than in patients with limited form of systemic sclerosis, but the data were not statistically significant (p> 0.05). The correlation between functional parameters of the respiratory system and duration of the disease in patients with SSc has not been identified. Conclusion: Airflow obstruction and isolated impairment of DLco are more common in patients with SSc. DLco measurement could be a useful diagnostic tool for SSc.