Early PP With HFNC Versus HFNC in COVID-19 Induced Moderate to Severe ARDS

HFNC will be initiated at 50 L/min (AIRVO2 or Optiflow, Fisher \&Paykel Health care Limited., Auckland, New Zealand) with temperature set at 37 oC. Nasal cannula size will be determined by the patient's nostril size (≤ 50%). FIO2 will be adjusted to maintain SpO2 at 92% to 95%. Flow and temperature will be adjusted based on patient's comfort and clinical response.

PP will be performed before or 1 hour after meal. Before PP, all the I.V. lines and nasal cannula will be checked by clinicians. PP will be performed by patient under the supervision of clinicians. Assistance will be offered if needed. If tolerated, PP will be maintained for at least 30 minutes, until the patients feel tired to keep that position. PP will be performed twice a day for the first 3 days after the patient's enrollment. FIO2 will be adjusted to maintain SpO2 at 92-95%.