If using mouth-to-mask ventilation without supplemental oxygen, what percentage of oxygen is delivered?

When using mouth-to-mask ventilation without the addition of supplemental oxygen, the percentage of oxygen delivered can be around 16%. This occurs because exhaled air contains approximately 16% oxygen, which is the result of normal respiration; the air we breathe in is about 21% oxygen, and by the time it is exhaled, some oxygen is utilized by the body and thus it is reduced.

In situations without supplemental oxygen, the mask allows for tighter sealing around the patient's mouth and nose to minimize any ambient air dilution, but the composition of the exhaled air is what is being delivered during the ventilation. While mouth-to-mask ventilation does improve the effectiveness of delivering oxygen compared to mouth-to-mouth, it remains inherently limited without additional supplemental oxygen supplied through the system. This is crucial to remember in any emergency situation to ensure the most effective response is utilized.