Immediate effect of mucus clearance device v/s conventional chest physiotherapy in patients with acute respiratory failure

INTERVENTION: Intervention1: acapella therapy: In this acapella device will be connected to expiratory port port of patients mechanical ventilator for 8‐10 min Control Intervention1: Conventional chest physiotherapy.: In conventional chest physiotherapy standard chest vibrations and percussion will be given CONDITION: Health Condition 1: J960‐ Acute respiratory failure PRIMARY OUTCOME: 1. Dynamic lung complianceTimepoint: 10 minutes SECONDARY OUTCOME: Oxygen saturationTimepoint: 10 minutes INCLUSION CRITERIA: 1. Patients on mechanical ventilator for more than 48 hours. 2. Type 1&2 respiratory failure patients. 3. Chest x‐ray having pulmonary infiltrates 4. Haemo‐dynamically stable patients. 5. Positive end expiratory pressure not more than 6 6. Fraction of inspired air given not more than 40%