Assessment of diaphragmatic function by ultrasonography in patients with systemic sclerosis and its relation to clinical parameters

Summary Background Diaphragmatic function can be affected in many diseases and disorders. Although systemic sclerosis (SSc) is a serious connective tissue disease that affects not only the skin but also the pulmonary and musculoskeletal systems, there is insufficient information about diaphragm function. Aims To compare the diaphragmatic parameters by ultrasonography (USG) in patients with SSc and healthy individuals and examine the relationship between these parameters and clinical features in patients with SSc. Methods This study included 13 patients with SSc and 15 healthy individuals. Muscle thickness (in deep inspiration T ins and at the end of calm expiration T exp ), changes in thickness (∆T), and thickening fraction at deep breathing were evaluated by USG. Skin thickness, pulmonary function tests, respiratory muscle strength, and the perception of dyspnea were measured as clinical features. Results The results of T exp, T ins, and ∆T were similar in both groups ( p > 0.05), albeit patients in the SSc group had less thickening fraction compared to the control group (79.9 ± 36.7 cm and 103.8 ± 20.6 cm, respectively, p < 0.05). The T ins , ∆T, and thickening fraction of the diaphragm were associated with skin thickness, pulmonary function test parameters, and respiratory muscle strength ( p < 0.05). Besides, there was significant correlation between muscle thickening fraction and perception of dyspnea ( p < 0.05). Conclusion These results confirm that diaphragm thickness and contractility can be affected in patients with SSc. Therefore, ultrasonographic evaluation of the diaphragm can play a complementary role to pulmonary function test and respiratory muscle strength measurement in the diagnosis and follow-up of patients with SSc.