Hey everybody, welcome back to X-Lan FM 5, the podcast where we take the questions you always wanted to ask and talk about them in a way that's easy to understand. You're your hosts, I'm Tim. Hey everyone, I'm Kevin. So Kevin, today we're talking about CPR.
And first of all, can we explain this question? If we breathe out carbon dioxide, why does CPR work since you're trying to get oxygen into someone's lungs? You're right. Our lungs, they exchange oxygen with carbon dioxide, but actually not all of it.
So your body doesn't consume all the oxygen in the air. That means that when you exhale into someone else's lungs, there's still a good amount of oxygen present. Ah, well that's a good true ELI-5 answer. Yeah, and expanding a little bit, you know, going in the air, it's, you know, 78% nitrogen, and carbon dioxide.
You remember how we did an episode recently on nitrogen? Of course, I remember that episode. Yeah, so going in, there's, like I said, 21% oxygen. And coming out is actually still 78% nitrogen, but now a lower amount of oxygen, about 15% oxygen when you exhale, and about 5% carbon dioxide.
So if you look at it that way, there's still a good amount of oxygen in it. You know, brain damage kicks in after a few minutes of less than 5% oxygen. So any little bit helps. And to put it into context, if you're performing assisted breathing on someone, it's probably because they can't breathe on their own.
So that 15% oxygen you're forcing into your lungs is much better than whatever little they were getting on their own account. And then, isn't there also the fact that not all the air coming out of your mouth is down to 15% oxygen? It hasn't all been exchanged, right? Yeah, that's also right.
The first one-third of the air we exhale has not really participated in that gas exchange in the lungs yet. So the first air that exits our mouths is fresh air, containing just about that 0.04% of carbon dioxide. So this air hasn't, you know, made it into your own lungs. Plus, you don't really have time to consume the air you fill your lungs with when doing CPR.
Now, some people talk about newer CPR methods not recommending mouth-to-mouth anymore, and instead just focusing on the chest compressions. That is correct. Over the years, there has been more focus on giving good compressions rather than the rescue breaths. The compressions, when done properly, should still provide air exchange, and it's more important to circulate blood than to send fresh air into the lungs.
I believe the Red Cross teaches to rescue reps only if you know the person doesn't have an obstruction or something preventing you from doing it properly. However, they say the compressions are by far more important. Yeah, it is interesting to see how they have evolved in the modern age. Hey, there's a good point, too.
We're talking about techniques in modern, primarily developed countries where there are now robust emergency service systems to help. It's in these places where they have move-force compression-only CPR because you know an ambulance and professional help is going to turn up rather soon. Now, it's still important to deliver oxygen, but it's actually sometimes from a bottle through a face mask or a breathing tube. The initial bystander rescuers should rather be focused on quality compressions and clearing the airway rather than performing mouth-to-mouth in these situations.
Okay, so since we're talking about compressions, during CPR, they talk about the frequency of compressions you need to do, and they say 100 to 120 chest compressions per minute. Why this fast when the average pulse is 60 to 80 beats per minute? Ah, so chest compressions don't have the same efficiency as a heartbeat, and so to get the proper amount of blood flowing through the body, a rate of about 100 to 120 is needed. Even doing CPR optimally is still not as good as normal heartbeats.
You know, some people put it at about 30% as effective. I mean, the goal is not to mimic a heart, but to buy time for the paramedics to help. Instead of the person's brain starting to die after five minutes, their brain could survive now for Following on from that, practically, when you are doing CPR, you do have to apply quite a lot of force to get the chest movement that you need, don't you? Oh yeah, oh yeah.
It can take more than like 20 to 60 kilograms, or rather 50 to 125 pounds of force, to compress the chest roughly 53 millimeters, or about two inches, during CPR. In fact, the recommended death for CPR at two inches will result sometimes in broken ribs or sternums for like 30% of the patients. Finally, CPR is one of those medical procedures that does come up in pop culture quite often. That's how we know about it.
That's why it's so popular. And in fact, the doll named Annie, which medical students practice CPR on, comes up in quite a few places. Annie, are you okay? Are you okay, Annie?
You know, does that at all sound familiar? Oh yes, Michael Jackson. That's right. The lyrics to Michael Jackson's Smooth Criminal were inspired by the CPR doll with Tussie Annie, and this dummy used to teach people how to properly perform CPR.
Crainies are taught to ask, Annie, are you okay, while performing CPR on the dummy? Very cool. Didn't know that story. Did you learn something new?
If you did, send us an email. We are at eli5thepodcasts at gmail.com. We love hearing from you, especially when you've got suggestions for us on future topics. And as always, thank you to the community at r slash explainthecom.fi.
We will see you all next week.