coronavirus disease 2019 related pneumonia is causing acute respiratory failure and this is the most common reason for ICU admission. We have several different way for respiratory support. HFNC is one of the new technics for oxygen support. Our main purpose to observe the effect of HFNC on coronavirus disease 2019 patients' ICU stay and mortality.

In the first group (group H), the data of patients undergoing HFNC treatment, and in group II (Group K), the data of patients who received COT with a reservoir mask were included.

In HFNC support, the current air temperature is 31-37 degrees, the flow rate is 30-60 lt / min, and the FiO2 value is targeted so that saturation is 93% and above. Initially, continuous treatment was applied intermittently after the partial oxygen pressure / fraction of inspired oxygen(fio2) ratio exceeded 250 and clinical well-being occurred.

In patients in Group K, fingertip saturation was targeted as 93% and above, and a COT was applied with a reservoir mask with a flow rate of 6-15 l / min.

The flow rate was calculated using the formula of FiO2 (%) = 21 + 4 * (liters / min) in patients undergoing COT. Noninvasive mechanical ventilation was applied to patients who could not be provided with adequate clinical and laboratory well-being in both groups (partial oxygen pressure / fraction of inspired oxygen ratio below 150) and invasive mechanical ventilation if this was insufficient.

Inclusion Criteria:

• We include the patient with acute respiratory failure related coronavirus disease 2019 (diagnosed with polymerase Chain Reaction), older than 18 year and supported by High Flow Nasal cannulae or conventional oxygen treatment(COT).

Exclusion Criteria:

• Patients with primary pulmonary disease, Glasgow Coma scale≤ 12 , respiratory acidosis in the first blood gases(ph≤ 7,2 - pCO2≥50) will exclude.

coronavirus disease 2019 patients admitted to the ICU for acute respiratory failure 15 march to 15 may