Capnography/Capnometry/ETCO2??

[itzfrank]

I'm trying to understand the differences... My medic book doesn't expound much... And I've got a few different perspectives. In our EMS system, we've got Colormetric ETCO2 devices... We also got a new pulse oximeter on one unit that measures PaC02 as well. We don't have any other means CO2 monitoring on any of our monitors that I'm aware of.

As far as my protocols go, We use the Colormetric device when we intubate as a placement confirmation. My book talks about all kinds of additional uses for intubated and non-intubated patients. I'm having trouble understand what an ETCO2 monitor looks like for the non-intubated patient. I understand the usefulness of it, just not how it works. Is it as simple as the Pulse Oximeter device, or is there some means of monitior expelled air in the non-intubated patient. Like I said, this is pretty much out of our scope in my area, I'm just trying to get a better understanding. Thanks in advance!

 

[VentMedic]

Your CO monitor is probably a RAD 57 by Masimo.
http://www.masimo.com/

Lots of info including the training video here:
http://www.masimo.com/MasimoU/index.htm

Sign on is easy and free.

Two good sites for capnography:

www.capnography.com

http://elearning.respironics.com/index_f.asp

Sign on is easy and free.

Under the CE section you will find:

Capnograpphy Principles and Clinical Applications

Respiratory Monitoring: Principles and Clinical Application of Volumetric Capnography

NPPV: Across the Continum of Care

On the Product training you will find a sophisticated ETCO2 monitor and the WhisperFlow CPAP device.

 

[VentMedic]

I'm trying to understand the differences... My medic book doesn't expound much... And I've got a few different perspectives. In our EMS system, we've got Colormetric ETCO2 devices... We also got a new pulse oximeter on one unit that measures PaC02 as well. We don't have any other means CO2 monitoring on any of our monitors that I'm aware of.

I just reread your post. Do you mean CO or carbon monoxide measurement?

PaCO2 is a direct measurement of CO2 by a blood analysis. The little "a" stands for arterial.

PetCO2 is the measurement from an end-tidal CO2 monitor.

SaO2 is a direct blood measurement.
SpO2 is from the pulse oximetry. And yes, they may vary for many reasons.

Capnography with give you both the quantitative value and graph.

Whatever you want to know about any of these measurements...just ask.

 

[csykes]

To add to VentMedic, capnometry is the numerical value, no wave forms. Capnography is the picture and usually, on most monitors, will have capnometry included.

 

[Devilz311]

We use both Colormetric, for initial confirmation, as well as waveform capnography on the LP12.

 

[reaper]

If you have Capnography, why would you spend the time for a Colometric?

 

[Sasha]

Don't mean to hijack the thread but I have a question regarding colometric device.

When discussing intubations in class, one of the instructors said you can get a false colometric reading if you're in the stomach and the patient had very recently drank a carbonated drink. Is that true?

 

[medic417]

http://emscapnography.blogspot.com/

 

[MSDeltaFlt]

Don't mean to hijack the thread but I have a question regarding colometric device.

When discussing intubations in class, one of the instructors said you can get a false colometric reading if you're in the stomach and the patient had very recently drank a carbonated drink. Is that true?

Yes you can. All those devices do is detect carbon. Carbon dioxide, the carbon from carbonated water. It doesn't matter. So it's not an absolute confirmation.

This is only antecdotal, but I can only come up with only 7 absolute confirmations (absolute in my book only) of proper ETT placement:

1. Direct visualization. Stick the blade in and see the tube in the trachea.

2. Capnography. There is only one type of waveform you get when you're in the lungs and you can't get it anywhere else. Thing is you must be able to read EtCO2 properly.

3. 2 view CXR. AP/PA and Lateral.

4. CT

5. MRI

6. Surgery. Cut the neck open and see it there: curgical cric, tracheostomy, autopsy.

7. Bronchoscopy.

You can get mist in the tube from the stomach. You can get false positive bilateral breath sounds. All those do is aid in confirmation along with positive colormetric change, equal rise and fall of chest, no epigastric sounds, with no change in ETT placment (ETT mark).

I also hope you guys chart that each and everytime you move your intubated patient. Because ETT's move. Every little bit helps in your charting. And you must be able to prove right there in black and white that it didn't move, or what you did to fix it if it did.

 

[emtjack02]

Just as a thought...some of the sources I've read lately say that capnometry may not be accurate if the pt does not have a perfusing ecg.

 

[csykes]

I assume by perfusing ecg you mean a heart beat, and if that is the case capnography would only work on the living. On the contrary, if gas is being exchanged in the lungs and the patient is being ventilated, you will get capnometrical changes, if not, consider misplacement, poor cpr, or anemia.

 

[VentMedic]

Just as a thought...some of the sources I've read lately say that capnometry may not be accurate if the pt does not have a perfusing ecg.

Accuracy is only relevant for the given situation. Trending may be more feasible then trying to determine "accuracy".

For even the best of situations, normal values may not be textbook. Nor, will the PetCO2 always match that of the PaCO2. That is the gradient discussed in the previous links in the sections concerning V/Q mismatching and deadspace ventilation.

In cardiac resuscitation, we use the ETCO2 as a guide that what we are doing might actually be working and a predictor of ROSC.

However, we do use capnography and not just capnometry during a code situation. The same for any diagnostic analysis. A number is only a number without a broader picture of a quality graph to give you some idea about the hows and whys to explain that number. A picture is worth many words. I only use capnometry for "spot checks" on known patients as I would for pulse oximetry.

Here is a good article:

http://ccforum.com/content/7/6/411

If you look at the end of the article, you will find several more references for good reading that you won't find in JEMS.

 

[rhan101277]

I have been reading up on this, we use the CO2 detectors, I haven't asked much about them. I did read that pulse oximetry can sometimes take minutes to show hypoxia of a patient who is just becoming hypoxic, where when using capnography you can tell immediately.

Obviously you will know something is wrong when someone stops breathing. But it is strange that you will see good pulse ox for a few minutes, I guess it is because it takes time for the body to use up the oxygen in the hemoglobin.

I know for sure we don't have the capnography equipment that shows the waveform. It seems it would be handy in being able to determine the hearts ability to pump blood besides just blood pressure.

It seems to me that blood pressure and capnography would be related. If you have lower blood pressure, you should have less gas exchange than normal etc.

 

[VentMedic]

I have been reading up on this, we use the CO2 detectors, I haven't asked much about them. I did read that pulse oximetry can sometimes take minutes to show hypoxia of a patient who is just becoming hypoxic, where when using capnography you can tell immediately.

ETCO2 can help identify a cause leading to hypoxia quicker than waiting for a pulse ox to reflect a desaturation. Examples are a plugged ETT or tube in the esophagus. It can also assist in a differential but it can not determine hypoxia. However, a person can actually be very well ventilated but extremely hypoxic.

We do use an ETCO2 monitor during a code to determine the effectiveness of CPR and probability of ROSC.

 

[Silverstone]

We use Zoll Monitors with EtC02 capnometry and capnography. We can view the pleth (wave form) directly underneath the ECG tracing. And our adapters to connect it from the ETT to the Ambubag are currently on back order from Zoll, and have been for the last month or so. So we are completely out.

 

[MSDeltaFlt]

ETCO2 can help identify a cause leading to hypoxia quicker than waiting for a pulse ox to reflect a desaturation. Examples are a plugged ETT or tube in the esophagus. It can also assist in a differential but it can not determine hypoxia. However, a person can actually be very well ventilated but extremely hypoxic.

We do use an ETCO2 monitor during a code to determine the effectiveness of CPR and probability of ROSC.

That door swings both ways. You can also have high sats and still be hypoventilated.

 

[el Murpharino]

Vent, according to this article, it seems to me like EtCO2 is just as important in predicting arrest survivability as how quick we initiate CPR, although it's the closed-chest compressions that are needed to increase the C02 delivery to the alveolar space for elimination and thus increase the ETC02 levels. Yet I'm seeing in the field plenty of EMT's and Medics who bag the patient WAY too fast, which would decrease their PETC02 as well, correct? Do you think we may start to see a shift away from the "every 5 seconds" to a longer period of time?

I guess this is why ACLS bugs me...they pretty much diminish the need for proper intubation and ETC02 readings in the current guidelines...too many contradictions, I s'pose.

 

[VentMedic]

Vent, according to this article, it seems to me like EtCO2 is just as important in predicting arrest survivability as how quick we initiate CPR, although it's the closed-chest compressions that are needed to increase the C02 delivery to the alveolar space for elimination and thus increase the ETC02 levels. Yet I'm seeing in the field plenty of EMT's and Medics who bag the patient WAY too fast, which would decrease their PETC02 as well, correct? Do you think we may start to see a shift away from the "every 5 seconds" to a longer period of time?

I guess this is why ACLS bugs me...they pretty much diminish the need for proper intubation and ETC02 readings in the current guidelines...too many contradictions, I s'pose.

The breath rate has changed to 8 - 10 breaths per minute or 1 breath every 6 - 8 seconds.

We do use ETCO2 as a predictor of survivability in the ED on almost every patient but only in the ICU if the monitor is nearby. Downtime and ineffective CPR will be some of the worst barriers to successful ROSC, not whether an ETT is established right away. Unfortunately, in the ED we do start taking bets on how long before we call a code by just listening to the report from the ambulance. It it sounds chaotic with sirens blaring and yelling in the background, I'll pour a cup of coffee in the ED staff lounge without fear of it getting cold before I return from the code. The ETCO2 monitor will almost always agree with us. But then, you don't need science to figure out some things.


ACLS is a guideline. ACLS has looked at many factors and has attempted to pick the ones that increase the chances and ones that may take away and/or "distract" from survivability. Intubation is still considered to be a definitive airway but it has been shown it doesn't have to be the first thing done if an airway can be maintained by other means such as with the BVM. ACLS still maintains that those who can intubate will still intubate.

EMT(P)s watching a monitor should not be an alternative for better education and improving the skill of using a BVM with or with a tube. If they are bagging too fast, the one who notices it should quickly point it out. There are also many other things involving V/Q relationships that will give a lower ETCO2 number and not just the ventilations as an issue. One should also become familiar with what can cause changes in CO2 production and what can cause changes in CO2 elimination. If one was to use the ETCO2 monitor for just the purpose of number watching while bagging, it could remain as poorly understood or misunderstood as the pulse oximeter.

 

[Ridryder911]

ACLS is a guideline. ACLS has looked at many factors and has attempted to pick the ones that increase the chances and ones that may take away and/or "distract" from survivability.

Great statement. Just alike protocols are, just guidelines, not the Gospel.