Capnography for DITF and other uses

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Permalink Reply by Eric on September 25, 2009 at 6:07pm

Ive used Etco2 for recognizing bronchiospasam in addition to the ones you mentioned. using etco2 waveform to diagnose pulmonary issues has become a big tool with services around my area

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Permalink Reply by dr-exmedic on September 25, 2009 at 9:17pm

I don't think that was a big enough study or ever repeated enough for people to hang their hats on it. The PA protocols certainly don't allow TOR on capnography readings.

There are lots of uses for capnography, although admittedly tube confirmation is the most important. Ever been on capnography.com?

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Permalink Reply by blair4630 on September 25, 2009 at 10:33pm

Tube confirmation is the only thing the PA state protocols mandate the use of EtCO2...therefore, unfortunately, that's all it gets used for in most places. The majority of services won't buy the side-stream cannulas unless other things like waveform to verify bronchospasm, differentials between hyperventilations vs. respiratory compensation for metabolic acidosis, etc. etc. become a mandated test in the protocols. As with so many other technologies, if it's not mandated by law, nobody wants to shell out the the money to buy the technology.

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Permalink Reply by Rob Theriault on September 28, 2009 at 6:25pm

Great discussion! We're required to monitor ETCO2 for all intubated patients. The interesting piece here is that I think the paper you referred to is now out of date. i.e. ETCO2 seems to be, and this is purely anectodal, much higher in in cardiac arrest since the CPR standards have changed to faster, deeper compressions with fewer breaths and lower tidal volumes. I've always keenly followed the literature on the prognostic ability of ETCO2 in cardiac arrest but I am now convinced that the numbers no longer apply.

I also think it's an essential tool for positive pressure ventilation for the head injured patient - the goal being that of keeping the ETCO2 close to the low end of normal (~35 mmHg).

If the service where I worked had a machine that allowed for monitoring of ETCO2 for spontaneously breathing non-intubated patients I would also love to monitor how patients with bronchospasm or acute exacerbation of COPD respond to bronchodilators or how patients with acute pulmonary edema respond to NTG and/or CPAP.

cheers
Rob (my blog)

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Permalink Reply by Jon P. Cloutier on September 28, 2009 at 10:24pm

Hey Rob,

Hope all is well up north.

I agree that the literature needs to be updated and I'm sure you know that these values were derived from manual CPR - not mechanical. Perhaps you will agree that there is no better biomarker than CO2 for measuring ROSC, circulation and respiration? We are all very good at what we do but I challenge anyone to convince me that they can get near normal EtCO2, B/P and SpO2 values from performing manual CPR. I believe that automated compression devices will continue to (positively) change the way we approach resuscitation. These things are achieving results that we only wish we could produce. In fact, I question whether the dosing regimen that we use in manual CPR is too much when using automated CPR devices. Perhaps 1 mg of EPI 1:10,000 may be the right does for manual compressions but too high of a dose with mechanical CPR given the more effective circulation with these devices. That remains to be studied.

Sorry for the tangent...

To your point about EtCO2 for use in the traumatically brain injured (TBI) patient for whom you suspect elevated intracranial pressure (ICP). I would wholeheartedly agree that this is a useful tool. In fact, this is the one time when I advocate for treating the monitor, not the patient. Before capnography our protocols would guide us to hyperventilate the patient with the BVM and deliver 20 - 24 breaths per minute with the intention of blowing off CO2. Hopefully it is no surprise that the #1 thing that effects ICP is carbon dioxide. We have a habit of bagging the soup out of patients (i.e. severely hyperventilating) which as we know inhibits oxygen from binding to the heme molecules on the RBC. By titrating the RR to a EtCO2 value on the low end, as you suggested of ~30 - 35 mmHg (depending on what literature you agree with), it may take only a few breaths per minute or it may take several. This will, in turn, reduce all the nastiness that is associated with TBI and ICP. Treat the monitor, not the patient - in this case only.

Good stuff!!!!

Rob Theriault said:

Great discussion! We're required to monitor ETCO2 for all intubated patients. The interesting piece here is that I think the paper you referred to is now out of date. i.e. ETCO2 seems to be, and this is purely anectodal, much higher in in cardiac arrest since the CPR standards have changed to faster, deeper compressions with fewer breaths and lower tidal volumes. I've always keenly followed the literature on the prognostic ability of ETCO2 in cardiac arrest but I am now convinced that the numbers no longer apply.

I also think it's an essential tool for positive pressure ventilation for the head injured patient - the goal being that of keeping the ETCO2 close to the low end of normal (~35 mmHg).

If the service where I worked had a machine that allowed for monitoring of ETCO2 for spontaneously breathing non-intubated patients I would also love to monitor how patients with bronchospasm or acute exacerbation of COPD respond to bronchodilators or how patients with acute pulmonary edema respond to NTG and/or CPAP.

cheers
Rob (my blog)

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Permalink Reply by Jon P. Cloutier on September 28, 2009 at 10:36pm

P.s. I think we're short changing ourselves by restricting EtCO2 to monitoring ONLY intubated patients. Aside from the obvious respiratory scenarios might it be helpful for determining whether an infarct is evolving or when a patient is going in to cardiogenic shock? Isn't it similar to monitoring the heart ONLY for chest pain patients? What about those patients with shortness of breath, syncope, palpitations, altered mental status, etc...

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Permalink Reply by pete jubie on October 8, 2009 at 7:49am

Where I am, New York State, all intubated patients need wave form capnography on them.. The EMS agencie where I am employed required it before it became manditory at the state level..
Also, when we use CPAP, we need to use wave form, by protocol.

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Permalink Reply by Joshua Todd on October 8, 2009 at 4:03pm

It is also an excellent adjunct for monitoring sedation waveforms in addition to the previously mentioned bronchospastic waveforms. We place most patients on capnography these days and virtually any patient that has a respiratory complaint or is receiving supplemental oxygen. If I am administering benzo's or a narcotic I will place the pt on ETCO2 and use it to help monitor and document their subsequent level of sedation.

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Permalink Reply by dr-exmedic on October 8, 2009 at 7:11pm

I have to say, this is one area of medicine where EMS has really gotten ahead of the ED. The only ETCO2 machines in our dept are the old IR-based ones that clip over ET tubes....

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