Oxygen safety assessment of High Flow Nasal Therapy use in an ambulance

High-Flow Nasal Therapy (HFNT) can fill the gap between standard oxygen therapy and NIV or mechanical ventilation. The high flow rates that make HFNT effective also create a significant fire and burn risk by increasing ambient oxygen concentrations to potentially explosive levels. Risk of explosion is high when the oxygen concentration exceeds 25%. The aim of this study is to determine technical issues, safety conditions and operating parameters of various HFNT settings commonly prescribed for acute respiratory failure in order to facilitate their potential use in ambulances. The experiment was conducted, with a standard ambulance fan turned on and off using Mercedes Sprinter Ambulance, Airvo3 device and SimMan 3G simulator in the Silesian Medical University Simulation Center. Airvo3 was used flow rate of 70/l/min and FiO2 1.0 with fan on, and 60 l/min and FiO2 decreasing progressively, starting from 1.0 and reducing by 0.1 increments with fan off. Oxygen concentration was measured inside the ambulance with 3 professional independent sensors placed in the cabin. Experiment was terminated at each attempt, when the concentration of the oxygen reached 25% and finally at FiO2 0.4 when the experiment time has reached one hour and the oxygen concentration was below 25%. erjor;12/suppl_17/142/TB1 T1 TB1 FiO2/flow [l/min] time to increase oxygen concentration to 25% on 2 sensors [min:sec] 1.0/60 12:47 0.9/60 14:02 0.8/60 16:32 0.7/60 20:23 0.6/60 22:09 0.5/60 34:31 Our study showed that the use of HFNC is safe in the ambulance with efficient ventilation for 60 minutes at a flow of 70 l/min and FiO2 1.0. With a faulty or switched off ventilator, the use of HFNC is safe at a flow of 60 l/min and FiO2 no higher than 0.4.