The aim of this study was to describe the changes in respiratory rate, heart rate and dyspnea, before and after using HFNC in patients presenting to our emergency department with ARF.

A retrospective cohort study was performed. To all adults presenting to the emergency department who used high flow nasal cannula to treat clinical signs of acute respiratory failure based on the presence of a breathing frequency ≥ 25 breath/min and increase work of breathing evidence by dyspnea, in-drawing, accessory-muscle use and/or diaphoresis despite conventional oxygen therapy ≥ 6 l/min. Demographic variables and clinical and gasometric parameters before and after two hours using HFNC were recorded.

Inclusion Criteria:

• patients aged ≥ 18 years
• attended between July 1st, 2015 and January 31st , 2017 in the Emergency Department of the Hospital Italiano de Buenos Aires
• with clinical signs of acute respiratory failure

Exclusion Criteria:

- Pulse oximetry > 90% breathing room air

Patients with and without a history of lung disease who used high flow nasal cannula. We defined clinical signs of acute respiratory failure based on the presence of a breathing frequency ≥ 25 breath/min and increase work of breathing evidence by dyspnea, in-drawing, accessory-muscle use and/or diaphoresis, despite conventional oxygen therapy ≥ 6 l/min.