Oscillating Positive Expiratory Pressure Devices and Acute Exacerbation of Chronic Obstructive Pulmonary Disease

Inclusion Criteria: * COPD patients, stages 3-4 according to GOLD guidelines 2016, with post bronchodilator FEV1/FVC \< 70% of predicted and FEV1 \< 50% with exacerbations necessitates hospital admission. * Smokers or Ex-smokers. * Able and willing to provide informed signed consent. Able and understanding the correct use of the bronchial clearing device. * Able to perform effectively spirometry. * Able and willing to receive the management plane as indicated including systemic steroids if seemed necessary. Exclusion Criteria: * Other obstructive pulmonary diseases or those do not fulfill the criteria of COPD diagnosis. * Nonsmokers. * Presence of major comorbidity causing organ dysfunction as cardiac (including severe pulmonary hypertension), renal, or liver impairment (not including diabetes, arterial hypertension, or obesity). * Presence of lobar pneumonia. * Suspicion of bronchogenic malignancy. * Any other complication either at admission or during hospital stay as pneumothorax, pulmonary embolism, myocardial infarction, acute coronary syndrome, cerebrovascular accidents, ... * Patients unable or not willing to provide informed signed consent. * Patients unable to use the bronchial clearing device. * Patients unable to perform spirometry. * Patients unable or not willing to comply to the management plan or the study protocol. * Patients receiving regular oral steroids or non-selective beta blockers.