Capnography

[Just Plain Ruff]

I haven't seen this many thread resurrections in I don't know how many years.  Maybe it will spark some good discussion.  

[kohlerrf]

When using a Bag Valve Mask if you are not using ETCO2 you have no Idea if you are ventilating a patient properly. The body and all its organs and systems only operate properly within a very narrow range of pH. We devote a substantial amount of ATP in our efforts to maintain this narrow pH range weather it be through bicarb release kidney excretion or ventilation, second by second the body struggles to maintain the pH so that all systems are "GO"! 

There is an indirect but very real relationship between End Tidal CO2 and the pH of the blood. The lower the ETCO2 the more alkalies the blood becomes and visa versa. While we do not generally know what the baseline pH of the blood is when we arrive at a patient in the field we do know the body is mapping too and if necessary trying to correct it.

If we come along with a BVM, intubate and start to ventilate without End Tidal CO2 we do know you will create and inconsistent minute volume. This inconsistent Minute volume will be reflected in an inconstant End tidal CO2. Because pH moves with CO2 the already sick body will now have to chase and inconstant pH value you create and may in fact never be able to compensate. For every deviation of the pH so goes the efficiency of all the bodily systems. Ventilating with a BVM and no End Tidal CO2? When does the mantra "DO NO HARM" come into play?

[paramedicmike]

Ventilating with a BVM and no End Tidal CO2? When does the mantra "DO NO HARM" come into play?

Oh, I don't know.  I think not ventilating and letting the patient die is far, far worse than ventilating without end tidal.  At least then you can wind up with a live patient and a potentially correctable blood gas.

Ideally, yes.  We would do everything perfectly in every instance.  Ideally, yes.  We would have ETCO2 hooked up every single time we have to manage a patient's airway.  Don't think for a second that I'm arguing not using it whenever possible.  However, we work with what we have.  We all know, especially in EMS, that this is a very uncontrolled environment.  Inconsistent minute volumes and a live patient is far better than a zero minute volume and a dead patient. 

[Off Label]

Here's the thing. CO2 is not poison. A respiratory acidosis, even a screaming respiratory acidosis on it's own, is very well tolerated by most patients. It's not an ideal physiologic state but is very easily corrected, unlike a metabolic acidosis which is far less tolerated, not in small part because of the reasons it exists in the first place.

A bigger risk is inadvertently and severely hyperventilating a more elderly patient because of the effect on cerebral blood flow. By and large, giving about 8 breaths per minute looking for a gentle rise in the chest will avoid any big problems. Oxygenation is what really matters.

The primary utility of et CO2 is demonstration that the tube is thru the cords and/ or the airway is patent. That's it. All of the other stuff that goes with it is nice, but at the end of the day, it's a tube/airway check.

 

 

 

[rock_shoes]

Here's the thing. CO2 is not poison. A respiratory acidosis, even a screaming respiratory acidosis on it's own, is very well tolerated by most patients. It's not an ideal physiologic state but is very easily corrected, unlike a metabolic acidosis which is far less tolerated, not in small part because of the reasons it exists in the first place.

A bigger risk is inadvertently and severely hyperventilating a more elderly patient because of the effect on cerebral blood flow. By and large, giving about 8 breaths per minute looking for a gentle rise in the chest will avoid any big problems. Oxygenation is what really matters.

The primary utility of et CO2 is demonstration that the tube is thru the cords and/ or the airway is patent. That's it. All of the other stuff that goes with it is nice, but at the end of the day, it's a tube/airway check.

 

 

 

If you have it use it. In the absence of blood gases SPO2 and EtCO2 are the only guides we have with respect to oxygenation/ventilation. We should be using them to guide our ventilation strategies.

[Just Plain Ruff]

 Ventilating with a BVM and no End Tidal CO2? When does the mantra "DO NO HARM" come into play?

 

well hell,  I remember in band camp, errr  in the 1990's and early 2000's when not a single service had anything like ETCO2 monitors.  We had pulse oximetry and that was it.  Man how far we've come.  I think we did most of our patients good when we didn't have it.  But to claim, "Do No Harm" mantra, is a bit of a stretch.  I have worked in several systems (not lately) but in 2014 that didn't have ETCO2's which based on budget, kept them from purchasing them.  

 

[Off Label]

If you have it use it. In the absence of blood gases SPO2 and EtCO2 are the only guides we have with respect to oxygenation/ventilation.

No they're not. Lung sounds, skin color, chest rise and fall are guides too. They're not subject to calibration errors, power failures or mechanical failures. Sure, if you have those things, take advantage of them. But they don't replace the training and skill of the medic by a long shot.

[paramedicmike]

No they're not. Lung sounds, skin color, chest rise and fall are guides too. They're not subject to calibration errors, power failures or mechanical failures. Sure, if you have those things, take advantage of them. But they don't replace the training and skill of the medic by a long shot.

Gotta agree with this.  While we are moving towards more quantifiable measures of the care we provide, and being asked to provide documentation to verify that care, there are still simple physical exam findings that can and will demonstrate that interventions we're performing are working.

Treat the patient not the number.  If you have a number to additionally verify your interventions then use it.  It will benefit, and may protect, you in the long run.  But don't rely on nothing else except for the number.  None of these things are independent of the other.  It is all a part of the patient care package.

[rock_shoes]

No they're not. Lung sounds, skin color, chest rise and fall are guides too. They're not subject to calibration errors, power failures or mechanical failures. Sure, if you have those things, take advantage of them. But they don't replace the training and skill of the medic by a long shot.

I'm not suggesting you replace the soft squishy thing between your ears. That's what will tell you whether or not you can trust the numbers. Having an end tidal certainly doesn't mean you shouldn't have a listen either. SPO2 and EtCO2 do however remain the only quantifiable numbers you're going to get on an ambulance anytime soon. If you have access to them and you refuse to use these well vetted and studied tools at your disposal your being a prat.

Don't believe me? Here's one of a great many papers regarding the use of EtCO2 to mitigate unrecognized esophageal intubation.

http://mastertrain.8m.com/masterimages/2013articles/The Effectiveness of Out-of-Hospital Use of Continuous End-Tidal Carbon Dioxide Monitoring on.pdf

[Off Label]

I'm not suggesting you replace the soft squishy thing between your ears. That's what will tell you whether or not you can trust the numbers. Having an end tidal certainly doesn't mean you shouldn't have a listen either. SPO2 and EtCO2 do however remain the only quantifiable numbers you're going to get on an ambulance anytime soon. If you have access to them and you refuse to use these well vetted and studied tools at your disposal your being a prat.

Don't believe me? Here's one of a great many papers regarding the use of EtCO2 to mitigate unrecognized esophageal intubation.

http://mastertrain.8m.com/masterimages/2013articles/The Effectiveness of Out-of-Hospital Use of Continuous End-Tidal Carbon Dioxide Monitoring on.pdf

like I said.... it's a tube check first and foremost. Using it or not using it wasn't part of my post, except to say, like you, if you have it, take advantage of it.

And it's very easy to fill the stomach with exhaled CO2 by mask ventilation.False positive ET CO2 happens with esophageal intubation

Edited February 5, 2016 by Off Label