Fig. 2

Peak (a), mean expiratory pressure (b) and negative peak of inspiratory pressure. Results are displayed as median, interquartile range, maximum and minimum. During HFOT_TRACHEAL, tracheal expiratory pressure increases proportionally to the gas flow. All HFOT_TRACHEAL settings limit the negative inspiratory pressure, especially as flow is set at 50 L/min, likely due to the capability of the high gas flow in an open system to match patient’s peak inspiratory flow. As compared to standard oxygen, 50 L/min, but not 30 L/min nor 10 L/min, increase tracheal peak and mean tracheal expiratory pressure