Background: The AirLife Open Mask made by Vyaire (Mettawa, IL) specifies that it delivers an FIO2 range of 0.24-0.9 between 1-15 L/min. The OxyMask made by Southmedic (Ontario, CA) specifies that it delivers an FIO2 of 0.24-0.9 between 1-15+ L/min. The Adult 3-in-1 Mask with Standard Connector made by Medline (Northfield, IL) specifies that, as a medium concentration mask, it delivers an FIO2 of 0.35-0.5 between 5-10 L/min. This study aims to test the average FIO2 delivered by each mask at 3 different flows. We hypothesized that there is no difference in the FIO2 delivery between each mask type. Methods: Each mask listed above was attached to an intubation trainer mannequin (Laerdal Medical, NY) and ASL 5000 (Ingmar Medical, Pittsburgh, PA) breathing simulator. The mannequin’s trachea was connected to the simulator using a T adapter, and an Ohio Medical Mini-Ox (Ohio Medical, Gurnee, Il) O2 analyzer was used to obtain an FIO2 reading in the trachea. The ASL simulator was set up using the normal adult patient model with a VT of 500 mL, frequency 12 breaths/min, and TI of 1 s. The oxygen flow set to each mask was 1 L/min, 7 L/min, and 15 L/min respectively. The simulator was allowed to run until the VT was stable and the FIO2 for each scenario was recorded once the measurement reached equilibrium. Each set flow and mask combination were performed 5 times each. The O2 analyzer was calibrated between each run. Results: At 1 L/min, the AirLife Open Mask, OxyMask, and Adult 3-in-1 Mask resulted in mean FIO2 values of 28.58%, 28.8%, and 28.96%, respectively. There was no statistically significant difference (F(2,12) = 2.060, P = .17). At 7 L/min, the mean FIO2 values were 49.04%, 51.82%, and 44.48%, respectively, with a statistically significant difference (F(2,12) = 70.950, P < .001). At 15 L/min, the mean FIO2 values were 54.1%, 61.6%, and 53.6%, respectively, with a statistically significant difference (F(2,12) = 212.896, P < .001). Conclusions: This study demonstrated that there was no statistically significant difference in FIO2 delivered among the three masks at 1 L/min with a normal breathing pattern. However, there was a statistically significant difference in FIO2 delivery among the three masks at 7 and 15 L/min with the same breathing pattern. Based on the above, our hypothesis is rejected.
Tedrow et al. (Tue,) studied this question.