Oxygen

[Brandon O]

Very well said, Halothane.

PaO2 is the direct driver of SaO2, but SaO2 itself is the clinically relevant target as far as tissue oxygenation.

 

[Clipper1]

I realize that some of you are trying to play devils advocate in this situation but in the end if you do not have ABGs you would not give O2 with someone satting at 99% because of the potential of resp alkalosis. If he was having trouble breathing an anti-anxiety med could be considered giving his condition or even vocal reassurance.

Withhold oxygen?
Apparently that is the message some might be trying to drive home if the "SpO2" is high.
The objecive should be to decrease work of breathing.
Are you going to with hold oxygen for someone who is suspect for a pulmonary emboli. The cassic sign might be rspiratory alkalosis but with a low PaO2. Also some one who is anxious does not always equal "hyperventilation". Their PaCO2 might actually be climbing due to air trapping or pending failure. Tachypnea does not always mean anxiety or "hyperventilation".

 

[Clipper1]

Very well said, Halothane.

PaO2 is the direct driver of SaO2, but SaO2 itself is the clinically relevant target as far as tissue oxygenation.

Do you also believe it is appropriate to with hold oxygen on someone who is trying in increase their oxygenation by increasing overall minute ventilation?

This would have similar results as telling someone with DKA to slow their breathing. Unfortunatelly some do fixate on an SpO2 and are quick to go with the "hyperventilation/anxiety" diagnosis and forget or not know about all the other possibilities.

I can quote from a textbook or websie also but EMS is very limited for obtaining SaO2 or PaO2 in the field. They are also limited for treatment to improve perfusion. What can an EMT do to improve cardiace output? Do you suggest to allow a pt to continue breathing at a high rate or giving a little supplemental O2 to help maintain their PaO2? We may also intubate someone with an SpO2 of 100% for a variety of reasons.

We seriously need to be discussing clinical assessment with potential problems and not allowing one number (SpO2) be a guide to withholding oxygen or assumig all is fine with the patient because the SpO2 is high.

 

[Brandon O]

Do you also believe it is appropriate to with hold oxygen on someone who is trying in increase their oxygenation by increasing overall minute ventilation?

No. But that's a separate matter. Someone may have a sat of 100% which is due to tenuous compensation in the presence of a respiratory challenge, but noting that compensation is a clinical matter (tachypnea, etc).

Knowing that patient's PaO2 would give you a better sense for how tenuous their SpO2 truly is -- whether they have a surplus of oxygen tension or barely enough to fully saturate their hemoglobin. But again, that's not a direct factor in oxygenation status, which seemed to be the topic here. Barring a failure of the equipment or some fairly unlikely confounders, a measured SpO2 of 100% does denote normoxemia; the patient's PaO2 was one of the factors that made that happen, but that's where its contribution ends.

Actual, total oxygen DELIVERY will involve factors like hemoglobin content and cardiac output and oxygen affinity and so forth. But PaO2 doesn't really measure these either. (Well, I suppose it technically speaks to oxygen affinity when compared to the sat...)

 

[Bullets]

Stop saying "withhold"

This implies that everyone should receive oxygen. Do medics withhold epinephrine, or duoneb? No. they administer it as needed. Oxygen is a medication like all others and should be administered as such

 

[Clipper1]

No. But that's a separate matter. Someone may have a sat of 100% which is due to tenuous compensation in the presence of a respiratory challenge, but noting that compensation is a clinical matter (tachypnea, etc).

Knowing that patient's PaO2 would give you a better sense for how tenuous their SpO2 truly is -- whether they have a surplus of oxygen tension or barely enough to fully saturate their hemoglobin. But again, that's not a direct factor in oxygenation status, which seemed to be the topic here. Barring a failure of the equipment or some fairly unlikely confounders, a measured SpO2 of 100% does denote normoxemia; the patient's PaO2 was one of the factors that made that happen, but that's where its contribution ends.

Actual, total oxygen DELIVERY will involve factors like hemoglobin content and cardiac output and oxygen affinity and so forth. But PaO2 doesn't really measure these either. (Well, I suppose it technically speaks to oxygen affinity when compared to the sat...)

If all of these is true, why has EMS been called? If the person is "sick" do they not benefit from an assessment beyond "SpO2"? All of the factors you mentioned do play a role in assessing a patient. One should not assume "normal" just because of a number on a pulse oximeter.

Do you take into consideration the WOB to maintain an SpO2 of 100%? If the patient has marked increased WOB, what exactly is "normal" about that 100%?

I think it should be stressed that nothing is too normal if the patient has to struggle for that 100%. The same if they are profoundly acidotic. We could also get into temperature correction for those who are doing TH s/p ROSC which also has a CO factor to be considered.

Granted this is a prehospital forum so many of these factors probably are not a concern in the short term.

 

[Clipper1]

Stop saying "withhold"

This implies that everyone should receive oxygen. Do medics withhold epinephrine, or duoneb? No. they administer it as needed. Oxygen is a medication like all others and should be administered as such

Would your indication also be based purely off of a number like SpO2? What if the patient is moving over 20 L of MV to maintain a high SpO2? Would you give oxygen or would you wait for them to tire and the SpO2 to drop to fit the number in your protocol?

That is the point I am trying to make since on this forum, the SpO2 is quoted and not much else about the clinical assessment.

 

[Carlos Danger]

Would your indication also be based purely off of a number like SpO2? What if the patient is moving over 20 L of MV to maintain a high SpO2? Would you give oxygen or would you wait for them to tire and the SpO2 to drop to fit the number in your protocol?

That is the point I am trying to make since on this forum, the SpO2 is quoted and not much else about the clinical assessment.

Do higher minute volumes improve oxygenation?

 

[Brandon O]

Do you take into consideration the WOB to maintain an SpO2 of 100%? If the patient has marked increased WOB, what exactly is "normal" about that 100%?

Like I said, the effort and compensatory mechanisms involved in maintaining a high SpO2 are obviously critical to assess. I'm only saying that, by and large, actual oxygen delivery (in the sense of hypoxemia) is fully and accurately represented by the oxygen saturation. All these other factors are different pieces of the puzzle.

I don't think we're disagreeing about anything.

 

[Clipper1]

Do higher minute volumes improve oxygenation?

In certain disease processes, yes.
This can be both a good thing and a bad thing.

 

[Carlos Danger]

In certain disease processes, yes.
This can be both a good thing and a bad thing.

What types of diseases processes?

 

[Clipper1]

What types of diseases processes?

Asthma, PF, COPD, infant/pedi RDS, PNA to name a few. Diseases which affect acid-base also affect breathing patterns. Some patients actually do what ICU practitioners attempt with ventilators. The body also attempts to correct the pH which can also affect the oxygenation curve.

There are good websites where you can read about respiratory diseases, acid-base and how the body attempts to compensate as well as how each are related. Just like SpO2, not just one factor is alone and everything is related. Working in an ICU is where you really see how this all comes together.

 

[Carlos Danger]

Working in an ICU is where you really see how this all comes together.

Well, I guess I better go spend some time in one of those ICU's, then.....

 

[EMT856]

If they could benefit from O2, why not? You are not going to hurt them by giving them high flow O2 en route to the hospital. If they coulda used it, but didnt get it, you are likely liable because of standards of care. My way of looking at it is, it cannot hurt at all, so why not try?

 

[STXmedic]

 

[TransportJockey]

If they could benefit from O2, why not? You are not going to hurt them by giving them high flow O2 en route to the hospital. If they coulda used it, but didnt get it, you are likely liable because of standards of care. My way of looking at it is, it cannot hurt at all, so why not try?

You're wrong. Oh so very wrong. And a good example of what is wrong with ems as a whole.

 

[Glucatron]

I would not have. If your protocols say different though, than go by that. If he looks good, mentation good, negative stroke scale and is not having SOB. SpO2 values were good too though I would treat pt not monitor. If he started to look really sick, lose mentation, then that ofcourse would change. /2 cents

 

[Anjel]

If they could benefit from O2, why not? You are not going to hurt them by giving them high flow O2 en route to the hospital. If they coulda used it, but didnt get it, you are likely liable because of standards of care. My way of looking at it is, it cannot hurt at all, so why not try?

Oh lord... No!

Oxygen can hurt! High flow o2 is contraindicated in stroke and Myocardial Infarction. Look it up.

 

[EMT856]

You're wrong. Oh so very wrong. And a good example of what is wrong with ems as a whole.

Explain exactly how 20-30 minutes of oxygen is exactly what is wrong with EMS as a whole?

 

[Glucatron]

Oh lord... No!

Oxygen can hurt! High flow o2 is contraindicated in stroke and Myocardial Infarction. Look it up.

What state do you work in where it's contraindicated? If they are sick enough, high flow O2 is an absolute must! Atleast 2lpm if nothing else!