1. Patients in palliative care2. Patients with imminent orotracheal intubation according to refractory hypoxemia with acute respiratory distress syndrome (ARDS), acute respiratory acidosis (pH &lt, 7.15, PaCO2 &gt,45 mmHg) with ARDS, requirement of airway protection.3. Patients with unsolved shock (reanimation phase or norepinephrine dose greater than or equal to 0.15 mcg/kg/min).4. Unstable arrythmias (bradycardia o tachycardia).5. Mental agitation or altered mental state (Glasgow Comma Scale &lt,10 points) that would impede cooperation to self-prone.6. Instability of the pelvis, vertebral column, or femur due to recent surgery or trauma. 7. Anatomical alterations that limit the adoption of prone position (severe kyphoscoliosis, muscle contracture, or other).8. Abdominal surgery in the last 15 days.9. Thoracic lesion or surgery in the last 15 days. 10. Pregnancy11. Intracranial hypertension 12. Deep vein thrombosis in the last 2 days. 13. Heart pacemaker surgery in the last 2 days. 14. Chest tube with air leak 15. Recent facial trauma or surgery16. Morbid obesity (BMI &gt,40 kg/m2)17. Pressure lesions or ulcers

1. Patients in palliative care2. Patients with imminent orotracheal intubation according to refractory hypoxemia with acute respiratory distress syndrome (ARDS), acute respiratory acidosis (pH &lt, 7.15, PaCO2 &gt,45 mmHg) with ARDS, requirement of airway protection.3. Patients with unsolved shock (reanimation phase or norepinephrine dose greater than or equal to 0.15 mcg/kg/min).4. Unstable arrythmias (bradycardia o tachycardia).5. Mental agitation or altered mental state (Glasgow Comma Scale &lt,10 points) that would impede cooperation to self-prone.6. Instability of the pelvis, vertebral column, or femur due to recent surgery or trauma. 7. Anatomical alterations that limit the adoption of prone position (severe kyphoscoliosis, muscle contracture, or other).8. Abdominal surgery in the last 15 days.9. Thoracic lesion or surgery in the last 15 days. 10. Pregnancy11. Intracranial hypertension 12. Deep vein thrombosis in the last 2 days. 13. Heart pacemaker surgery in the last 2 days. 14. Chest tube with air leak 15. Recent facial trauma or surgery16. Morbid obesity (BMI &gt,40 kg/m2)17. Pressure lesions or ulcers