koobs

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Had an attending ask me this but I can't find the answer. He said to assume a 20ish healthy incubated patient. I have found the alveolar has equation, but can't finure what to use for arterial. Fick?
 

sigrhoillusion

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PAO2 = ( FiO2 * (Patm – PH2O)) – (PaCO2 / RQ).

It depends on certain factors. Are you at sea level? Do they have a normal resp quotient? What's the PACO2.

If you are to assume everything is "normal" with a PaCO2 of 40 then it would be ~663mmHg
 
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koobs

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PAO2 = ( FiO2 * (Patm – PH2O)) – (PaCO2 / RQ).

It depends on certain factors. Are you at sea level? Do they have a normal resp quotient? What's the PACO2.

If you are to assume everything is "normal" with a PaCO2 of 40 then it would be ~663mmHg
Yeah that is what I thought. I said about 700 just doing the math in my head but he said no...
 
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pgg

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So -

He didn't follow that by telling you the answer and how he arrived at it?

That's some mighty fine teaching there, Lou.
 

AdmiralChz

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So -

He didn't follow that by telling you the answer and how he arrived at it?

That's some mighty fine teaching there, Lou.
Ugh I used to have a few obnoxious attendings that would ask basic anesthesia physics-ish questions like this, give an answer and never explain. Very, very frustrating.
 

dhb

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Tiva or not? You also have to factor in the gas: 6% des will take a chunk off of that 660
Temperature of incubation is also a game changer.
 

Maverikk

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PaO2 is measured. PAO2 can be calculated using the equation, quick and dirty way is to multiply the FiO2 by 6 and you'll get close assuming no extremes of elevation, normal pCO2
 

BLADEMDA

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What's the highest number anyone on SDN has ever seen on an ABG for the PAO2? There is theoretical and then there is real world.
 

proman

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I guess I'm cheating but you can get PaO2 above 760 by going hypothermic. Our co-oximeters just give a blank result at around 24 degrees. I'll post a picture on Wednesday from my next circ arrest case. If you want to be pedantic, remind your attending that he didn't specify temperature or pressure.
 
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