EtCO2 question

P

patzyboi

Forum Lieutenant
Messages
148
Reaction score
1
Points
18
I know the normal EtCO2 range is 35-45 mmHg, but would this change with the administering of Oxygen?
 
No.

Go study what EtCO2 and what the numbers mean... not just the range, so you know a little bit about what you're looking at and talking about. Not to be mean... Just want you to learn.
 
That is the difference between knowing and understanding.

Great question, knowing what you know about physiology, do you think EtCO2 should change with oxygenation?
 
I don't understand the question. Would the normal range change? Would the value change ?
 
Sorry, but how would the 'normal' range change. It's a normal range for a reason...anything outside the normal range is abnormal.
 
This question sounds a lot like the whole hypoxic drive issue/myth/whatever you want to believe or was taught...I understand what you are asking but I think you don't have a clear grasp on why the CO2 may be high or low. The illness you are treating may also require oxygen, however a change in CO2 may or may not be a direct result of that. There are so many variables in the treatment and range of pathologies that the actual question itself may be a moot point.

And to the question of what is "normal", apply that to an acute ketoacidosis case and define "normal". Many healthcare practitioners try to correct the CO2 to a normal range without trying to address why the CO2 is in the basement. Or of a severe V/Q mismatch where the numbers don't reflect what is happening in the arteries. To a healthcare professional being hammered by all kinds of pathologies on an hourly basis, "normal" is a nebulous phrase.
 
ETCO2 is a measure of ventilation, not oxygenation. Sure, the two aren't mutally exclusive, but in this case it is.
 
Expired C02 is a product of metabolism, cardiac output & pulmonary blood flow (the two are related but not synonymous), and ventilation (shunt physiology). Manipulating any one of those will change Etc02, and each one of these factors can be affected by oxygen administration.

I think the OP's question is whether administering oxygen will cause a noticeable change in Etc02. The answer to that is that it depends on several complicated factors. I don't think I've ever seen a case where giving or withdrawing oxygen changed Etc02 appreciably, and I can't think of a scenario where it would, but I certainly can't say that it would never happen.

Read up on carbon dioxide transport (the Haldane effect, especially) and the A-a gradient.
 
Just had a thought...we've all been thinking about the physiological effects if any. It occurred to me that the question could be geared to placing nasal cannula or a mask on a patient who is also getting their EtCO2 reading through nasal cannula. THAT would change the EtCO2 reading but not the EtCO2 itself.
 
ThadeusJ said:
Just had a thought...we've all been thinking about the physiological effects if any. It occurred to me that the question could be geared to placing nasal cannula or a mask on a patient who is also getting their EtCO2 reading through nasal cannula. THAT would change the EtCO2 reading but not the EtCO2 itself.
Click to expand...
Even with oxygen it's not going to effect the reading
 
You must log in or register to reply here.
Back
Top