Oxygen Enrichment of Expired Gas for Mouth-to-Mask Resuscitation

Abstract

BACKGROUND: One drawback to expired air ventilation for resuscitation is the relatively low oxygen concentration delivered (FDO₂). METHOD & MATERIALS: We measured the FDO₂ provided to a bench model, during mouth-to-mouth and mouth-to-mask ventilation, without supplemental oxygen, by 12 volunteers skilled in Basic Life Support (BLS). The bench model consisted of resuscitation mannequin, trachea, and test lung with an oxygen analyzer, capnograph, and turbine spirometer incorporated into the tracheal portion. We then added an oxygen enrichment device (OED), and measured FDO₂ when oxygen was supplied to the device at flowrates of 5, 10, and 15 L/min. Participants were then instructed to inspire from the OED, the "inhalation technique," and FDO₂ was measured again at the three flowrates. RESULTS: The mean FDO₂ during expired air ventilation was 0.18. With supplemental oxygen at 5 L/min, mean FDO₂ increased to 0.29; with 10 L/min, to 0.36; and with 15 L/min, to 0.43. Using the inhalation technique, FDO₂ increased significantly (p < 0.05) compared to the standard technique. When the inhalation technique was used with oxygen at 5 L/min, mean FDO₂ rose to 0.36; with 10 L/min, to 0.57; and with 15 L/min, to 0.71. CONCLUSION: The use of supplemental oxygen during mouth-to-mask ventilation increases FDO₂, and the use of the OED with the inhalation technique provides a higher FDO₂ than can be achieved with supplemental oxygen alone. The OED may be a useful device to achieve better oxygenation of victims during resuscitation. COMMENTARY: Mouth-to-mask ventilation offers distinct advantages to the BLS provider. Future design of mouth-to-mask devices should allow for oxygen enrichment and provide a filter as a barrier between patient and rescuer.