40 mmHg ETCO2 during cardiac arrest?

[Underoath87]

So the last 2 codes I have worked, my medic opted to transport after 10 minutes on scene because the capnometry reading was around 40 mmHg. These were elderly men that had been down for 5-10 minutes prior to our arrival without CPR. The reading came from an iGel and a LP15. The first pt was in VFib until the hospital called it. The second was in asystole with a few brief periods of PEA for nearly an hour until the ER terminated efforts.
I'm still the EMT, so I wasn't working the monitor and able to double check or troubleshoot the issue.

Am I correct in thinking that a normal capno value in these cases seems inconceivable, and that it must be some sort of error?

I've asked several other medics at work, and none had an answer besides: "I don't know. Maybe it was just good CPR".

Is there some know issue involving falsely elevated readings with the iGel that are causing us to transport patients that should probably be terminated in the field?

PS: the second pt received an amp of bicarb, but not the first. And CO2 was already around 40 before the bicarb.

 

[NomadicMedic]

Good CPR and increased capnometry is usually seen as an indicator of impending ROSC. Curious if you were also using an ITD and a CPR device like a LUCAS.

 

[STXmedic]

The first two things that come to mind are good cpr and hypoventilation. I've also seen a full pneumonectomy cause a continuously increasing EtCO2 due to us ventilating her with the typical 8-10/min (we didn't know she had a pneumonectomy).

 

[Underoath87]

No ITD. Compressions were all manual.

 

[Carlos Danger]

That's interesting. Are you sure it was accurate - i.e. there was a good waveform?

Seems unlikely, but if so....as the others said, there was some really good CPR going on.

 

[Underoath87]

We weren't using the waveform option, unfortunately. This was simply numerical. If the situation occurs again, I'll try to get a look at the waveform.

 

[281mustang]

I've seen it once. It was an unwitnessed arrest and he maintained in the 30s all the way until the 20 minute mark at which point med control insisted he be transported. He immediately plummeted between all the breaks in compressions and sub-standard CPR done while wheeling him to the unit and en route.

I've always found the whole "if you have good capno, transport them to the hospital" mindset to be pretty absurd.

 

[Underoath87]

I've seen it once. It was an unwitnessed arrest and he maintained in the 30s all the way until the 20 minute mark at which point med control insisted he be transported. He immediately plummeted between all the breaks in compressions and sub-standard CPR done while wheeling him to the unit and en route.

I've always found the whole "if you have good capno, transport them to the hospital" mindset to be pretty absurd.

Agreed. These patients had both been down for 15+ minutes before we even moved them to the truck. And then it was a 20 minute ride to the ER, with only 2 medics in the back (we're pretty rural and the fire departments mainly run 2-man engines). A positive outcome was hopeless, especially once we started moving them.

 

[281mustang]

Agreed. These patients had both been down for 15+ minutes before we even moved them to the truck. And then it was a 20 minute ride to the ER, with only 2 medics in the back (we're pretty rural and the fire departments mainly run 2-man engines). A positive outcome was hopeless, especially once we started moving them.

By the time we pulled into the ER bay it had been around 45 minutes since the call was originally placed, obviously the doc called it before we even wheeled him into the room. This was a 90-something year old guy in diapers, no one is going to continue running that.

This was in the middle of the night so I can only assume med control just wanted to push it off on someone else so he could get back to sleep being that he couldn't justify giving permission to cease efforts with his capno where it was.

 

[VFlutter]

Without waveform its hard to really say. Is IGel a LMA?

 

[STXmedic]

Without waveform its hard to really say. Is IGel a LMA?

Who the hell is this guy??

 

[MonkeyArrow]

Without waveform its hard to really say. Is IGel a LMA?

Yes.

 

[WolfmanHarris]

You might not be able to get the waveform, but the LP15 saves a ton in the background. Print a trend or if you use an ePCR system that let's you review your data do a continuous complete dump and you can get a good feel for ETCO2 across the call. If the ETCO2 started that high and persisted I'd probably lean more towards it being inaccurate then being related to the patient. Ditto if the ETCO2 was extremely variable the whole time and didn't persist at 40mmHg.

A sudden spike in ETCO2 is linked to ROSC and improved outcome. Beyond that I'm not aware of anything that would account for that.

 

[WolfmanHarris]

Did a quick pubmed search. If anyone wants full text of any of these PM me, I should have full text access to them through work or school.

"Quantitative relationship between end-tidal carbon dioxide and CPR quality during both in-hospital and out-of-hospital cardiac arrest." Resuscitation. April 2015.
http://www.ncbi.nlm.nih.gov/pubmed/25643651

Found compression depth increased ETCO2 and increased RR decreased ETCO2. Confirmed higher ETCO2 with ROSC than not (34.5±4.5 vs 23.1±12.9mmHg, p<.001) That average ETCO2 in the ROSC group was higher than I would have expected.

"Systematic Review and Meta-Analysis of End-Tidal Carbon Dioxide Values Associated With Return of Spontaneous Circulation During Cardiopulmonary Resuscitation." Journal Intensive Care Medicine. April 2014.
http://www.ncbi.nlm.nih.gov/pubmed/24756307

Found ETCO2 in ROSC had avg. of 25mmHg. Suggests that goal ETCO2 in resuscitation may need to be higher.

"End-tidal CO2 as a predictor of survival in out-of-hospital cardiac arrest." Prehospital Disaster Medicine. June 2011.
http://www.ncbi.nlm.nih.gov/pubmed/22107764

Also found increased ETCO2 with less than 25% drop from initial value predictive for ROSC. 26.6mmHg is the mean for the ROSC group. This one was most interesting for me since I've tended to focus on a spike in ETCO2 as predictive; I wasn't aware of the value or an initially high ETCO2. So forget what I said above. I'm glad I decided to procrastinate tonight.

 

[NYBLS]

I'm still not sure why you are transporting after only being on scene for 10 minutes and still actively doing compressions...

 

[Chewy20]

I'm still not sure why you are transporting after only being on scene for 10 minutes and still actively doing compressions...

x2

Also, you need to be careful with ETCO2 readings and Igels. We had a ton of problems with the readings until we addressed what the problem was. Which I forget what the problem was.