Differences in Inhaled Air Oxygen Concentrations Among Products of High-Concentration Non-Rebreather Reservoir Masks

Abstract

Background:

High concentration nonrebreathing reservoir masks (reservoir masks) used for patients with hypoxemia vary in shape by product. A good mask fitting and the ability to inhale gas from the reservoir bag during inspiration are the keys to administering a reliable high concentration of oxygen. It has been reported that FIO₂ delivery by conventional products is affected by mask fit. The EcoLite reservoir mask reports a more consistent FIO₂ delivery based on mask fit. An investigational bench study was performed to evaluate the differences, if any, in FIO₂ delivery between a conventional reservoir mask and the EcoLite reservoir mask at varied inspiratory flows and O₂ flow delivery.

Methods:

A bench study between a conventional reservoir mask (Inspiron oxygen masks three in one type) and the EcoLite reservoir mask was performed using an artificial lung (HR1101) and a mannequin (Laerdal airway management trainer) to simulate spontaneous breathing. Each mask was applied to the mannequin per product instructions. An oxygen analyzer (Multigas/Flow unit DF-220R) was placed in the left bronchi (the right bronchi was completely closed) and oxygen was delivered through each mask at 6, 8, 10, 12 and 14 L/min. Inspiratory flow for the artificial lung was set at 20, 30, 40, 50, 60, 70, 80 90, and 100 L/min for each O₂ flow delivered. The bronchi FIO₂ was recorded for each procedure and measurement was measured three times at each run.

Results:

The EcoLite mask exhibited higher inspired oxygen concentrations at each oxygen flow and inspiratory flow. The cumulative mean FIO₂ across set parameters was 64% (42%-96%) for the EcoLite mask and 50% (32%-77%) for the Inspiron oxygen mask three in one type. With a mean difference of 13.9 (2-31). Inspiratory flow impact on FIO₂ revealed a mean difference of 25.8 at Vinsp 20 L/min and 10 at Vinsp 100 L/min favoring the EcoLite. At an inspiratory flow of 60 L/min, the inspiratory oxygen concentration increased with each mask as the oxygen flow was increased.

Conclusions:

Reliable delivery of oxygen concentration delivery is necessary diagnostically and therapeutically. The EcoLite mask provided an FIO₂ consistently higher than the conventional product observed. This may be attributed to mask fit, valve assembly, and reservoir bag function. These results may impact clinical decisions in product use and applications. Further studies are needed to assess the clinical impact of this product.

Oxygen concentration of each reservoir mask

Oxygen flow rate	EcoLite mask range of FIO2	Conventional mask range of FIO2
6L/min	0.42-0.74	0.32-0.47
8L/min	0.46-0.86	0.36-0.55
10L/min	0.52-0.88	0.4-0.64
12L/min	0.54-0.96	0.42-0.67
14L/min	0.53-0.96	0.43-0.77