Performance of Open Oxygen Mask Design versus Conventional Oxygen Delivery Devices: A Simulation Study

Background:

Vyaire Medical has recently created an open-faced oxygen mask, Vyaire Open (VO) that is designed to direct flow towards the nares and mouth via multiple jet orifices. The manufacturer claims that this device is superior in tracheal FIO₂ delivery across a range of flow. This suggests that it eliminates the need for usage of multiple oxygen delivery devices as a patient’s FIO_{2 requirements change. The VO specifies flow (1–15 L/min and flush) and expected FIO2 from 0.25-0.85. The purpose of this study was to compare FIO2 performance between the VO and standard oxygen masks.}

Methods:

The following oxygen masks were compared to VO: A simple mask (Vyaire), OxyMask (open design from Southmedic), partial rebreather (Vyaire), and non-rebreather (Vyaire). An adult mannequin head (Michigan Instruments) was attached to a breathing simulator (IngMar ASL 5000) which recorded FIO₂. Each mask was sealed to the mannequin head to prevent leaks. The simulator was set to closed-loop volume control mode with V_T = 320 mL, C = 50 mL/cm H₂O, R = 4 cm H₂O/L/s, f = 15, increase = 25%, hold = 0%, release = 30%. Each oxygen mask was run at the recommended flows: simple mask 5–10 L/min, OxyMask 1–15 L/min, flush, partial rebreather and non-rebreather mask 10–15 L/min, flush. Each flow was verified with a Citrex H4 flow analyzer (imt Medical) prior to attaching the mask for FIO₂ measurement. Each experiment was repeated once.

Results:

For VO: at low flows (1–6 L/min) the measured FIO₂ was higher than that specified by the manufacture, at flows 7–10 L/min the measured FIO₂ was within the specified range, and at flows >10 L/min the FIO₂ was below the specified range (see graph). The results for FIO₂ across all devices are shown in the table.

Conclusions:

In this simulation study we found the measured FIO₂ for VO varied from the manufacture’s specifications in the package insert. As expected, performance varied greatly among devices. The FIO₂ was generally higher for the VO than the OxyMask. The simple mask outperformed both VO and OxyMask. Finally, both the partial and non-rebreather outperformed all the other devices. This study reinforces the notion that oxygen delivery cannot be reliably predicted and must be titrated using blood saturation measurements.

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