DOI: 10.1177/30682576261501745 ISSN: 3068-2576

Optimizing oxygen delivery in duckbill bag-valve-mask devices during spontaneous breathing

Wai-Hung Yu, Kwok Ming Ho, Yu-Yeung Yip
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Introduction

Pre-oxygenation is often performed with bag-valve-mask (BVM) devices whose oxygen delivery performance during spontaneous breathing is incompletely characterized. Duckbill-valve BVMs without an expiratory valve are prone to air entrainment during inspiration. This study evaluated how patient valve configuration and ventilatory pattern influence oxygen delivery during simulated spontaneous breathing with two duckbill devices.

Methods

In a mechanical lung simulator, we tested two adult BVMs: a duckbill device without an expiratory valve (Med-Rescuer) and one with a disc-type expiratory valve (Laerdal The BAG II). Devices were supplied with oxygen flows of 8, 15, or 30 L/min. Spontaneous breathing patterns were programmed across a broad range of volumes (250–1000 mL) and rates (15 and 25 breaths per minute). Additional runs for Med-Rescuer included a PEEP valve (5 and 10 cm H 2 O) to reduce air entrainment.

Results

For Med-Rescuer, delivered oxygen fraction ( FDO 2 ) decreased significantly once volume exceeded 250 mL ( P < .001), plateauing around 0.66–0.72 at higher volumes and oxygen flow of 15 L/min, independent of rate. Laerdal The BAG II maintained higher FDO 2 (0.74–0.92) across most volumes. Increasing oxygen flow from 8 to 30 L/min improved FDO 2 for both devices ( P < .001), with Laerdal consistently delivering higher FDO 2 than Med-Rescuer at all flows ( P < .001). Crucially, adding a PEEP valve to Med-Rescuer increased the FDO 2 from 0.71 to 0.98 ( P < .001), with no additional benefit seen at 10 versus 5 cm H 2 O PEEP ( P > .99).

Conclusions

The duckbill BVM incorporating an expiratory valve delivered higher and more stable FDO 2 across the tested range of simulated volumes and rates than the duckbill device without an expiratory valve. The FDO 2 delivered by the duckbill system without an expiratory valve could be substantially improved by higher oxygen flow rates and, most effectively, by adding a PEEP valve.

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