ROX Index in Acute Respiratory Failure

Inclusion Criteria: * Participants admitted to RICU with type I and type II respiratory failure requiring NIV support with one or more of the following : 1. PaO2/FiO2 less than or equal to 300 mmHg despite supplying oxygen at a flow rate ≥ to 10 l/min for ≥ 15 min 2. Patients requiring ventilatory support due to increased respiratory rate ≥ 25 breaths/min or using accessory muscles of respiration Exclusion Criteria: * 1\. Absolute indication for intubation like coma, hemodynamic instability, or life-threatening arrhythmia. 2\. Contraindication to NIV like untreated pneumothorax, pneumothorax with air leak, widespread facial burn or trauma, tracheotomy,or active upper gastrointestinal bleeding. 3\. Resusal to participate in the study