Background: The effect of using high flow oxygen delivery through the nasal cannula (HFNC) in COVID-19 patients has been associated with different results. This study aimed to evaluate the effect of different HFNC temperatures in COVID-19 patients.

Methods: Patients were randomly divided into three groups under high current oxygenation with temperatures of 31, 34, and 37. Except for the temperature, other device settings were set equally. After 24 hours, clinical conditions were on the agenda and compared with the conditions before the intervention.

Results: Fever, sore throat, malaise, diarrhea in patients of 31 degree group and indicators of nausea, cough, body pain, headache have changed the most in 37 degree group. Abdominal pain has shown the greatest change in the 34 degree group. PR, DBP, and SpO2 indices changed the most at 31 degrees and RR and SBP at 37 degrees. PR, RR, SBP and SPO2 indices showed significant values in intra-group comparison, and in inter-group comparison, only PR, RR indices had significant differences. In intra-group analysis, PaCO2, WBC, CRP, ESR and ferritin had significant changes, and in inter-group comparison, none of the indicators had significant differences.

Conclusion: Based on the results of the present study, reducing the temperature in the use of HFNC can improve the clinical conditions of patients with COVID-19.