High Flow Oxygen Therapy Effect on Healthy Subjects

Diaphragm thickening fraction.

ultrasound measurements were performed by an expert operator (the same in all cases). The ultrasound measurement was performed using a high-resolution linear transducer in real-time in B-mode. The diaphragm thickness was measured at the end of expiration and the end of inspiration of the same ventilatory cycle and the average value of 3 ventilatory cycles was recorded. A 2-minute washout period was allowed between each test condition to avoid the summation of effects. The DTf and PTPes/min were calculated for each subject in each available condition (baseline - without flow- , wtih 20 and 40 liters per minute): DTf = End Inspiratory Diaphragm thickening - End Expiratory Diaphragm thickening / End Expiratory Diaphragm thickening x 100

Time frame: Immediately after 5 min of each condition (baseline, 20 and 40 liters per minute) the diaphragmatic thickness was measured at the end of inspiration y de la expiration during 3 consecutive respiratory cycles (each cycle is between 3 and 10 seconds)