Evaluation of Impulse Oscillometry in patients with SarcoidosisEvaluation of Impulse Oscillometry system in patients with pulmonary Sarcoidosis

Introduction: Sarcoidosis is a multi-organ systemic inflammatory disease with respiratory system involvement in more than 90% of cases. On Spirometric evaluation a restrictive defect with reduced vital capacity (VC) is characteristic, airflow obstruction occurs in 30 to 50% of patients with pulmonary sarcoidosis. Spirometry may be difficult to perform in patients with respiratory distress. IOS is simple and requires minimal patient co-operation. Objectives: To evaluate the parameters obtained by Impulse Oscillometry System in Sarcoidosis. Methods: The participants were 28 Sarcoidosis patients recruited from pulmonary medicine OPD and 17 age matched healthy controls. Lung function was assessed by Spirometry and airway resistance and reactance by IOS. Results: Mean age of patients was 51.82±12.15. Mean R5(resistance at 5Hz), R20(resistance at 20 Hz), Fres (resonant frequency), R5-R20 and AX(area of reactance) was higher and X5(reactance at 5Hz) was lower in patients as compared to controls. R5 was significantly elevated in group1 (FEV1/FVC 80%, n=10) patiens. X5 and R5 was highly correlated to all Spirometric indices. Area under the curve (AUC) for R5, X5, R20, R5-R20 was >0.8(highly accurate). ROC curve analysis indicated that at cut off of 0.43, R5 had sensitivity of 75.00% and specificity of 76.47% in patients as compared to controls. Conclusion: Characteristic changes in IOS indices were found in patients with Sarcoidosis. R5 may help be useful in detecting early manifestations of airflow limitation in pulmonary sarcoidosis patients.