a simple question about sats.

loving2024, BSN, RN · May 16, 2015

Mavrick, BSN, RN · May 16, 2015

It's an artery until it turns into a capillary.

hyhero89 · May 16, 2015

then this statement is false?

SpO2 stands for Peripheral capillary oxygen saturation. It is an estimation of the oxygen saturation level.

I think it can be said that p stands for pulse oximetry

(Just for convenience maybe?)

not peripheral capillary...

pre-nurseshan · May 16, 2015

Here's a link where GrnTea gives a pretty detailed explanation of this:

https://allnurses.com/nursing-student-assistance/spo2-vs-sao2-266863.html

hyhero89 · May 17, 2015

still struggling here. but thanks for the link.

FlyingScot, RN · May 17, 2015

Reviewing the anatomy of the vessels will help tremendously in understanding how pulse oximetry measures arterial saturation. Understanding how the pulse ox actually does this and does it indirectly is actually quite interesting.

The arterial side of anatomy goes: artery to arterioles to capillary bed.

The venous side goes: vein, venules, capillary bed

[ATTACH]18285[/ATTACH]

So you see there IS arterial blood in the fingertips.

The linked article does an excellent job of explaining how the actual machine works. It's important to know that pulse oximeters, unlike saO2 monitors only read ON the pulse when there is a surge of arterial blood into the capillary bed. The diode is further engineered to be able to differentiate between the oxygenated blood vs the de-oxygenated blood by using both infra-red and red light sources.

Oximetry | Johns Hopkins Medicine Health Library

Pretty amazing actually.

Hope this helps.

vanilla bean · May 17, 2015

I found a link from Philips Medical (one of the many manufacturers of pulse oximeters) that you may find helpful. It includes some of the same information that has already been provided by PPs, but has some graphics that may be helpful, and it goes into further detail. It can be found here: http://incenter.medical.philips.com/doclib/enc/fetch/586262/586457/Understanding_Pulse_Oximetry.pdf%3Fnodeid%3D586458%26vernum%3D2

a pulse oximetry is used to measure SaO2, while the clip is applied to the patient's fingertip,right?

Also, take care not to confuse SpO2 with SaO2. SpO2 is the measurement obtained via pulse oximetry, while SaO2 is the measurement obtained by arterial blood gas analysis (venous blood can also be analyzed, yielding an SvO2 measurement). There is a glossary of terms on p. 13 of the linked manual that explains more precisely the difference between SpO2 and SaO2.

hyhero89 · May 24, 2015

thank you first. will read anyminute!

hyhero89 · May 24, 2015

God.. thanks you two flyingscot and vanilla bean. haven't thought of functional hemo and non functional hemo... it was really helpful! Oh and flyingscot, link 18285 attachment doesn't work :crying2: