ABG during long code

[RevEM]

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Hi guys,
long time lurker that finally registered!

there was a code on a hypothermic guy the other day that went on for a good while. he was eldery and was found down outside with air temp around 10 degrees. ems had him for maybe 30 mins (ET tube, IVs, CPR) before arriving in the ED and he was last seen about an hour before he was found down.
In the ER he was warmed, ACLS continued, i stat labs. The ABG had a p02 of 60 which seems pretty low. the tube had been confirmed with visualization. so i got to thinking about long codes and hypothermia and how does that change the abg. it's quite possible the guy was dead for an hour or so before arriving. would you expect such a low pO2? you cant trust the pulse ox either since the pt is so cold. Just wondering what is expected if anyone has had this kind of case before.

 

[Greenbbs]

how hypothermic was he? hypothermia shifts the curve to the left, so if he was really cold, you'd expect a lower pao2 on the gas.

 

[RevEM]

how hypothermic was he? hypothermia shifts the curve to the left, so if he was really cold, you'd expect a lower pao2 on the gas.

EMS reported 25 C...i'm not sure how they got that as it certainly was not rectal. by the time he got a foley the bladder temp was 30 C. the abg was drawn before he hit 30 i think because it took awhile to get the temp probe hooked up.

I was also wondering if it could be venous since it must have been hard to get a pulse even with cpr...

 

[Rendar5]

the machines need to correct for blood temperature. It may be possible the machine was not calibrated for that low at emperature. I will say that pO2 of 60 sounds too high to be a venous on someone who's been down for so long.

 

[yahoomail]

Hi guys,
long time lurker that finally registered!

there was a code on a hypothermic guy the other day that went on for a good while. he was eldery and was found down outside with air temp around 10 degrees. ems had him for maybe 30 mins (ET tube, IVs, CPR) before arriving in the ED and he was last seen about an hour before he was found down.
In the ER he was warmed, ACLS continued, i stat labs. The ABG had a p02 of 60 which seems pretty low. the tube had been confirmed with visualization. so i got to thinking about long codes and hypothermia and how does that change the abg. it's quite possible the guy was dead for an hour or so before arriving. would you expect such a low pO2? you cant trust the pulse ox either since the pt is so cold. Just wondering what is expected if anyone has had this kind of case before.

pO2 is low and pCO2 is high on a hypothermic patient as a result of the temperature, that is a known fact.

 

[proman]

pO2 is low and pCO2 is high on a hypothermic patient as a result of the temperature, that is a known fact.

Care to explain that? Both carbon dioxide and oxygen follow Henry's Law.

 

[GeneralVeers]

I'm curious as to why you would get a blood gas after a "prolonged code". If there's no return of spontaneous circulation, then you'd expect pH to be way off, and possibly the paO2 (depending on the effectiveness) of compressions. Regardless, the neurologic outcome is poor. As far as I can tell the ABG wouldn't change your management from the usual ACLS protocols.

 

[RevEM]

I'm curious as to why you would get a blood gas after a "prolonged code". If there's no return of spontaneous circulation, then you'd expect pH to be way off, and possibly the paO2 (depending on the effectiveness) of compressions. Regardless, the neurologic outcome is poor. As far as I can tell the ABG wouldn't change your management from the usual ACLS protocols.

So I talked to the resident running the code that day. The ABG came as part of the istat that lab had drawn. The only real reason labs were even drawn was to check for the potassium. if that had been >9, then they would have stopped right away. since it was basically normal, they warmed him up in order to call it.
since the pulse ox was not reliable and neither was the end tidal CO2, that's why they just took a look with the glide scope (I love that little machine). The ABG was not really to check anything as it sounds like you can't trust it anyway, it was just part of what the lab had drawn to get lytes.

 

[Hernandez]

Hi guys,
long time lurker that finally registered!

there was a code on a hypothermic guy the other day that went on for a good while. he was eldery and was found down outside with air temp around 10 degrees. ems had him for maybe 30 mins (ET tube, IVs, CPR) before arriving in the ED and he was last seen about an hour before he was found down.
In the ER he was warmed, ACLS continued, i stat labs. The ABG had a p02 of 60 which seems pretty low. the tube had been confirmed with visualization. so i got to thinking about long codes and hypothermia and how does that change the abg. it's quite possible the guy was dead for an hour or so before arriving. would you expect such a low pO2? you cant trust the pulse ox either since the pt is so cold. Just wondering what is expected if anyone has had this kind of case before.

Yes I would expect the PaO2 to be low in a hypothermic pt, as well as PaCO2 and the pH to by off as well. a pH of 7.4 in a hypothermic pt is acidotic....

the machines need to correct for blood temperature. It may be possible the machine was not calibrated for that low at emperature. I will say that pO2 of 60 sounds too high to be a venous on someone who's been down for so long.

You can correct without the machine being calibrated, for every degree C difference (for hypothermia)
pH will increase by 0.015
pCo2 will decrease by 4%
pO2 will decrease by 7%

a PaO2 of 60 would be about right for a pt with a temp ~32 degrees C.

I don't use the pH or pCO2 correction, mainly the pO2 when we're cooling pts.

Temp (C) PaO2
20 27
30 51
35 70
36 75
37 80
38 85
40 97

The ABG was not really to check anything as it sounds like you can't trust it anyway,

you can trust it, you just have to understand the changes that occur and when they're that cold to know how cold they are so you can correct the numbers

 

[rocuronium]

The only real reason labs were even drawn was to check for the potassium.

Checking potassium is the primary reason I get asked to do blood gases at cardiac arrests.

I just want to point out, although I'm sure it goes without saying, that a PO2 of 60 (regardless of patient temperature) is pretty crappy at a code. That is assuming they are being bagged with FiO2 1.0.

In my experience, knowing the PO2 at a true code isn't really good for anything other than satisfying curiosity. And, speaking of curiosity, the thing I am most curious to see from the ABG results is the lactate. It lets me classify where on the spectrum of screwed the patient lies.