VICOR Study-High Frequency Chest Wall Oscillations (HFCWO) in Patients With Acute Respiratory Failure and Hypersecretion

Inclusion Criteria: * Diagnosis of acute respiratory failure (ARF) or acute on chronic respiratory failure (including patients having home oxygen therapy, HFNC, NIV) both hypercapnic ARF (PaCO2 \> 45 mmHg; PaO2/FiO2 \<300) or hypoxaemic (PaCO2 \<45 mmHg; PaO2/FiO2 \<300); * Informed consent from patient or legal tutor; * Accessory respiratory muscles use; * Respiratory rate above 25 apm; * Use of non invasive respiratory therapy (NIRT) NIV+/-HFNC or HFNC alone since RICU admission * Kelly neurological index ≤ 3 * Excessive airway mucus secretion (clinical evaluation asking the patient to cough) and inability to efficiently remove secretions (evaluated with the Cough Peak Flow (CPF) measurement. A CPF under 270 Lpm is highly suggestive of inadequate cough which prevent the patient from adequately manage and remove airway secretions. * Cough score \< 3: in the case of inability to perform CPF measurement due to poor patient collaboration, cough adequacy will be evaluated by a respiratory physiotherapy with a semiquantitative score ("Cough score") based on the measurement of sputum volume produced after coughing three times (1 point: less than 2 mL, 2 points: 2-6 mL, 3 points: more than 6 mL). Exclusion Criteria: * Patient unwillingness or incapability to provide informed consent * Need for subcontinuous NIV(more than 20 hours per day) * Kelly neurological index \>3 * Cardiac arrest * Severe haemodynamic instability (more than two amines required); * acute coronary syndrome; …