Background Heated humidified high-flow nasal cannula (HHHFNC) oxygen therapy is a commonly used non-invasive mode of respiratory support in Paediatric Intensive Care Units (PICU) around the world. The safe level of maximum flow rate in HHHFNC therapy is disputed although a flow rate of 2 L/kg/min is believed to be safe. Manufacturers recommend flow rates based on cannula size, however there is concern that this approach may lead to very high flow rates and cause complications.

Aim To describe the use of HHHFNC therapy, flow rates used and complications in PICU.

Methods Prospectively collected data on all patients who received HHHFNC therapy in a single centre multi-disciplinary PICU between 1 October 2015 and 31 January 2016 were analysed. Demographics, diagnostic categories, flow rates (starting and maximal) and complications were determined.

Results During the study period, 158 episodes of HHHFNC therapy use on PICU were captured. Median age was 40 months (range: 6 days to 17 years). Median starting flow rate was 1.8 L/kg/min (range: 0.18 to 6.9 L/kg/min) and maximum flow rate was 1.9 L/kg/min (range: 0.18 to 7.7 L/kg/min). Median length of therapy was 3.6 days (range: 1 hour to 13.2 days). Table 1 shows the different diagnostic categories in which HHHFNC therapy was used. Table 2 demonstrates that mean starting and maximal flow rates were more than 2 L/kg/min in patients less than 10 kg, and significantly higher in patients<5 kg than patients 5 to 10 kg and>10 kg. No complications were reported.

Conclusions HHHFNC oxygen therapy is used as a mode of respiratory support in children with a variety of conditions. The flow rates used in babies less than 5 kg were significantly higher than in older children. However, no adverse effects were seen. We speculate that flow rates higher than 2 L/kg/min can be safely used in short term HHHFNC oxygen therapy in PICU.