When a pocket mask or bag-mask is not available, it may be necessary to give mouth-to-mouth breaths during CPR. Mouth-to-mouth breathing is very effective in delivering oxygen into the person’s lungs without putting the rescuer at a high level of risk. The rescuer’s exhaled air contains approximately 17% oxygen and 4% carbon dioxide. This is in contrast to the 100% oxygen available with ventilation with 100% high flow oxygen and the 21% oxygen that is available in room air that we breathe.
BLS course
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