A Prospective Observational Cohort Study of Awake Prone Position Ventilation Strategy in Patients With Acute Respiratory Failure

Inclusion Criteria: * 1.Older than 17 years, admitted to the ICU;2.Patients with acute respiratory failure meet the following conditions：①Under the condition of breathing air at rest, PaO2 of subjects is lower than 60mmHg and/or PaCO2 is higher than 50mmHg; ②Under the support of COT and HFNC, PaO2/FiO2 of the subject is less than 250; ③ Under the support of NIV ; Exclusion Criteria: * 1.Refusing to cooperate with active treatment; 2.Immediate need for intubation as determined by the treating team.3Patients with hemodynamic instability and moderate to high dose of vasopressors (norepinephrine dose ≥ 0.15 mcg/kg/min)；4.Contraindication to PP (e.g. vomiting, abdominal wound, unstable pelvic/spinal lesions, pregnancy \>20/40 gestation, severe brain injury)；