arterial oxygen saturation

[laughs]

Because if you hit a certain point and you know that looking-- And that SaO2, that little oxygen saturation, the little bitty thing we put on people's fingers, it very strongly correlates with a PaO2.

And people are like, "Oh, it's just an estimation." Pshaw.

Like, it's pretty good, you know?

PaO2 is approximately 80 to 100 millimeters of mercury.

SaO2 is 95 to 100.

So these ranges can vary slightly depending on the laboratory, the age, altitude, clinical circumstances, or even which reference you're looking at.

But for board style questions, these are the numbers I want living in your brain.

A couple things to note.

One is that the pulse ox can fall pretty fast, right? Remember, the pulse oximeter, the SpO2, the SaO2, this is all hemoglobin saturation.

That is what it's telling you, right? The percent it is giving you is the hemoglobin saturation.

And this can fall fast if you are on the steep part of the curve.

Pause if you need to.

Correct answer is A, they're on the steep portion of the oxygen dissociation curve.

Remember, if we just draw it out one more time, there's this steep portion here where small changes in the PaO2 lead to big changes in the SaO2 oxygen saturation.

Then there's this plateau area up here, whereas changes in the PaO2 lead to very little change in the SaO2.

Patients experiencing a STEMI benefit from this training and knowledge of the area as well.

Paramedics can obtain a 12-lead ECG and SAO2 within minutes of the onset of symptoms and administer aspirin, nitro, oxygen, and morphine as appropriate to ACS patients.

If a patient's ECG shows an ST elevation MI, transport to a facility with 24-7 interventional cath lab would be the most appropriate to ensure the patient receives PCI within 60 minutes of first medical contact.

Because it's their job, EMS crews are generally familiar with the hospital capabilities for their area.

It's a way that we can understand oxygen loading, oxygen unloading, and oxygen delivery.

The foundational kind of basics, what we've talked about in the past, is essentially how full is the hemoglobin, right? What is the SpO2 or the SaO2 or the hemoglobin saturation, right? All these, as we talked about in that other episode, are synonymous, very similar, but But the foundational kind of oxygen dissociation curve is what is the saturation of those hemoglobin as related to the amount of dissolved oxygen in the blood, the PaO2.

But the more advanced question, the one that's much more clinically applicable and the one we're going to focus on today is even with hemoglobin saturations being full or optimal or adjust or what have you, is there enough oxygen actually reaching the tissues, right? Is that hemoglobin unloading that oxygen? Is there enough oxygen content in the blood in general? And that depends not just on the oxygen hemoglobin dissociation curve, but it depends on a bunch of stuff.

Total oxygen content, cardiac output, hemoglobin concentrations, affinity, tissue extraction, what have you.

So the SAO2 or the saturation of oxygen in the arterial system, this is similar to the SPO2, right? That's what you see on the monitor.

You put a pulse oximeter on a patient's finger or earlobe and the monitor kicks out a percent.

The SPO2, the SAO2, these are... overlapping numbers, also synonymous with the amount of oxygen saturation of hemoglobin, because that's what the SpO2 is actually looking at, and the SaO2 is actually looking at.

It's looking at the percent of hemoglobin saturated with oxygen.