Bag CPAP vs Standard Oxygen Therapy in Acute Hypoxemic Respiratory Failure

1. Inclusion criteria All patients aged 18 years or older will be included in the study if they meet the following criteria: * De novo acute respiratory distress, characterized by the presence of dyspnea at rest, the use of accessory muscles for breathing, or a respiratory rate of 25 cycles per minute or more. * Hypoxemia, defined as a SpO2/FiO2 ratio less than 315 or a PaO2/FiO2 ratio less than 300 mmHg (if arterial blood gas is available) despite an oxygen therapy of 6 L/min. FiO2 will be estimated by the rule of 3% (Coudroy formula)(18,22). SpO2 should be less than 98% when assessing the SpO2/FiO2 ratio. 2. Exclusion criteria Patients with one of the following criteria will be excluded from the study: * Absolute contraindications to CPAP: patient's refusal, uncontrollable vomiting, upper gastrointestinal bleeding, open or sucking chest wound, pneumothorax not drained, craniofacial trauma, severe burns to the face, severe upper airway obstruction, traumatic tetraplegia at the initial stage, tracheostomy. * Moderate to massive pleural effusion not drained * Cardiac arrest, severe ventricular arrhythmias, and shock defined as the need for vasopressor support (adrenaline, noradrenaline, or dopamine) * Altered level of consciousness (GCS below 12), repetitive convulsions, or status epilepticus * Do not intubate or resuscitate order before the inclusion in the study * Refusal to participate, already included in the study, enrollment in another interventional trial on acute respiratory failure