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It’s not ALL carbon dioxide. You are actually pretty inefficient at extracting oxygen so much of it remains when you exhale.
New standards eliminate mouth to mouth in favor of continuous chest compressions. The moving up and down of the chest is enough to pull air in
If one person’s lungs stop inhaling, they have 0% oxygen in their lungs. Normal atmosphere is made up of around 20% oxygen. Human exhales still have 15% oxygen in them. By forcing our 15% exhale into the non breathing person’s lungs, their lungs have a chance to absorb the oxygen and exhale the co2 in their lungs. Any breath is better than no breath since your brain and organs continue to use the oxygen in your bloodstream.
When emergency services arrive, they usually attach 100% oxygen to a mechanical breathing device to continue to oxygenate the victim’s blood.
The breathing isn’t the most important part. The compressions are the main concern in CPR. Pumping blood to the brain is what you’re trying to do. Also, CPR isn’t that effective. Out of hospital survival rate is about 12%. 30ish% in hospital survival.
I ee the Oxygen thing answered, but one thing to note is that breathing is triggered by high CO2, so while in CPR you will be getting 19-20% O2 but also higher CO2 which will trigger breathing response, a stimulus that can be beneficial in such situations
The air you breathe in is 21% oxygen. The air you breathe out is 16.4% oxygen. The air you breathe out still has WAY more oxygen than it has carbon dioxide, and both the air you breathe in and the air you breathe out are equally 78% Nitrogen.
You don’t breathe out Carbon Dioxide; you breathe out a gas that’s got a higher percentage of Carbon Dioxide.
Your lungs only absorb a small percentage of the oxygen you inhale so when you exhale, there is still a considerable amount of oxygen in the air you expel.
It’s by no means an ideal system. It’s far more effective to ventilate the patient with pure oxygen and a bag-valve-mask setup but you’re talking about an emergency situation where you make the most of whatever resources you have. Your body also has very little oxygen demand when you are in cardiac arrest. But nowadays, the AHA mostly recommends compression only CPR if you’re a bystander waiting for paramedics to arrive. It’s not that the breaths don’t work, it’s just that your body has several minutes worth of oxygen in circulation when your heart stops and the real challenge is circulating that oxygen to the brain. So you’re better off just doing continuous compressions and not stopping for the rescue breaths.
You don’t fully convert oxygen to carbon dioxide in one breath, especially when you’re breathing in and out so quickly
Aside from all the comments that have pointed out that you still exhale a good amount of oxygen, it’s actually not recommended that you do mouth to mouth resuscitation as a bystander during CPR anymore, the chest compressions are the important part. A bunch of studies were showing that mouth to mouth resuscitation wasn’t really doing much if anything. That was like 20 years ago.
[https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1071045/](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1071045/)
Do compressions only if you see a teen or adult collapse. Breaths are only needed for drowning, drug overdose, and little kids. AHA instructor here.
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