Now, I love this picture.
Look at that. It's a little red blood cell, he's gonna get an oxygen mask on.
I think it's hilarious, but I do have a weird sense of humor.
But, look, he's hanging on to that oxygen tank for dear life.
Or remember, red blood cells job is to carry oxygen around to the rest of the cells, that's what they do.
They're not super smart but they are really efficient,
so when we're talking about FiO2, you know that second part of the PaO2/FiO2 ratio,
this represents the fraction of inspired oxygen.
It's the fraction concentration of the oxygen the patient is inspiring or breathing in.
Now room air, take a deep breath, okay take another one,
that's always a good thing particularly when you're studying
but room air is 21% and you may see that written as 0.21 or 21%
but that's roughly the fraction of inspired oxygen in room air, the average setting.
Now, FiO2 can range from 21% which is room air to 1.0 or 100%, so keep that in mind.
If I'm not -- if I don't have any extra oxygen on, like my little friend in the picture,
then I'm likely breathing 21%, but if I keep adding oxygen mask, cannulas, intubation,
I can increase the FiO2 to 100%.
Now, if I'm just standing here breathing an FiO2 of 21%, that means I'm doing okay.
My respiratory rate right now as you can see on video is normal.
I don't seem like I'm really working to breathe, so everything is relatively normal.
I'm right at 21%, I appear to be okay.
We could draw some lab work or do a pulse ox to validate that,
but pretty much, you know, I'm doing alright.
Room air is more than just that 21% oxygen and I wanted to make sure you knew that.
You think about, yeah, I know room air is 21%, but wait a minute, what's the rest of it?
Well, big old chunk of it is nitrogen, we also got carbon dioxide, argon, and some other stuff.
Depending on where you live, there might be some really weird other stuff,
but for the most part, I wanted you to have a visual picture,
it says room air, that's why we have the window open, is 21% oxygen.