TY - JOUR T1 - Lung Mechanics Affect Inhaled Oxygen Concentration With Low Flow Devices: An In Vitro Evaluation JF - Respiratory Care VL - 65 IS - Suppl 10 SP - 3440927 AU - Shu-Hua Chiu AU - Hui-Ling Lin Y1 - 2020/10/01 UR - http://rc.rcjournal.com/content/65/Suppl_10/3440927.abstract N2 - Background: Inspired oxygen fraction (FIO2) of low-flow oxygen therapy devices is greatly affected by breathing patterns and parameters, such as tidal volume, respiratory rate and inspiratory to expiratory ratio (I:E). The impact of lung mechanics on FIO2 delivered by low flow oxygen devices is not well explored. Methods: A dual training/test lung (Michigan Instrument) was connected to an oxygen analyzer and then to an intubation training mannequin. Three breathing patterns were set with tidal volume 500 mL, and (1) a normal lung breath pattern with respiratory rate of 20 breaths/min, and I: E of 1:2, compliance 100 mL/cm H2O, and airway resistance 1 cm H2O/L/min; (2) a restrictive lung breath pattern with respiratory rate of 25 breaths/min, and I: E of 1:1.4, compliance 30 mL/cm H2O, and airway resistance 1 cm H2O/L/min; and (3) a obstructive lung breath pattern with respiratory rate of 14 breaths/min, and I: E of 1:4, compliance 100 mL/cm H2O, and airway resistance 20 cm H2O/L/min. A simple oxygen mask with oxygen flow 10 L/min, a non-rebreathing mask with oxygen flow 10 L/min, and a nasal cannula at 1-6 L/min were randomly placed on the face of the mannequin. The FIO2 under each condition was recorded every 3 minutes for a total of 15 minutes, and measurement were repeated for 5 times (n = 5). Results: Figure 1 shows FIO2 measured with oxygen devices and breath patterns, and Figure 2 illustrates the comparisons of FIO2 using a nasal cannula with different flow and lung conditions. The FIO2 with normal lung parameters were significant lower with a simple mask and a nasal cannula at each flow. The equations from linear regression (R2 = 0.962-0.968) showed Y = 4.28X+19.79 for normal lungs, Y = 6.16X+19.4 for restrictive lung disease, and Y = 7.36X+18.27 for obstructive lung disease. Conclusions: Lung conditions with various breathing parameters and mechanics influence FIO2 with low flow oxygen devices. Comparisons of FiO2 among devices under different lung conditionsFiO2 measured with nasal cannula with different oxygen flow amont various breathing parameters ER -