Evaluation of the FreeO2 System for Oxygen Weaning After Acute Hypoxemic Respiratory Failure (EVOLUERA)

Inclusion Criteria:

• Age ≥18 years
• Acute hypoxemic respiratory failure requiring high-flow nasal oxygen therapy for at least 12 hours
• Fraction of inspired oxygen (FiO₂) ≤35%
• Peripheral oxygen saturation (SpO₂) ≥ the predefined lower target threshold:
• 88% in patients at risk of hypercapnia
• 94% in patients without risk of hypercapnia
• Women of childbearing potential must use an effective contraceptive method (oral contraceptives, injectable contraceptives, intrauterine device, double-barrier method, contraceptive patch); women must be postmenopausal for at least 24 months or surgically sterilized
• Patient's oral agreement and absence of written refusal to participate, indicating that the participant has understood the study objectives and required procedures and agrees to participate and comply with study-related requirements and restrictions
• Affiliation with or beneficiary of the French social security system

Exclusion Criteria:

• Age <18 years
• Uncontrolled acute respiratory acidosis requiring invasive or non-invasive mechanical ventilation
• Unstable peripheral oxygen saturation (SpO₂)
• Excessive bronchial secretions
• Carbon monoxide poisoning
• Severe cardiocirculatory failure (mean arterial pressure <65 mmHg without fluid resuscitation and/or requiring vasopressors, and/or severe arrhythmia)
• Acute neurological failure (Glasgow Coma Scale <15, or new-onset sensorimotor deficit)
• Acute kidney injury requiring renal replacement therapy
• Known untreated severe obstructive sleep apnea