Eli5: When doing CPR, why does it help to breathe into the person’s mouth, when we exhale co2?

Question

Eli5: When doing CPR, why does it help to breathe into the person’s mouth, when we exhale co2?

In: Biology

Answer 1

We are not exhaling into their mouths. An exhale is the natural course of breathing to remove the CO2. In CPR we are taking a breath of air into our mouths and blowing that into the recipients mouth. The air does not go through our respiratory tract and into our lungs/circulation so oxygen is not removed and it does not have the same CO2 by-priduct produced by natural breathing and circulation.