Nasal High Flow Therapy versus Non-Invasive Ventilation for ARDS: open-labeled randomized control study

INTERVENTION: NHF group: After randomisation, patients were treated with NHF (60L/min) during 30minutes and switched to NIV(CPAP 5cmH2O) during 30minutes as the crossover study. After the comparison, patients were treated with NHF(60L/min) continuously. NIV group: After randomisation, patients were treated with NIV (CPAP 5cmH2O) during 30minutes and switched to NIV(60L/min) during 30minutes as the crossover study. After the comparison, patients were treated with NIV(60L/min) continuously. CONDITION: ALI/ARDS based on the AECC criteria PRIMARY OUTCOME: PaO2/FIO2 on NIV(CPAP 5cmH2O) vs. NHF(60L/min) SECONDARY OUTCOME: Trend of PaO2/FIO2; Borg scale, respiratory rate; reduction rate of endotracheal intubation; Ventilator free days in 30days; Over all survival rate, hospital day; hospital mortality; Progression Free Survival rate INCLUSION CRITERIA: 1) ALI/ARDS based on the AECC criteria 2) Stay in ICU or ER‐ICU 3) PaO2/FIO2 300 or less on the conventional oxygen therapy