CPAP and CO Poisoning

[medic001918]

But, you are measuring two totally different aspects of Respiration: Ventilation and Oxygenation with each device.

I don't disagree with you. It's been my experience that capnography will give you a better indicator since the two often times (not always) go hand in hand. You always have to look at the total picture being presented by your patient though.

Shane

NREMT-P

[afeefma]

This is a very interesting subject. Even though, I would have to say that this patient might have developed another problem with his CO Poisoning. The reason is becuase he improved after placing CPAP. I would have appreciated more information in regard to his physical examination and what it revlead in terms of Lung Sounds.

Some people develope what is called HAPE (High Altitude Pulmonary Edema) and in his case, I am not really sure but lung sounds would make a difference. Giving the fact, that CPAP does not work or affect the pressure of inspired oxygen. It only gives a constant pressure that will keep the Alveoli Open and creates more surface area for adeqaute gas exchange. It has no affect on displacing Carbon Monoxide off the Hemoglobin Molecules and that's why Hyperbaric Chamber is the Gold Standard of treating such conditions.

The fact that his SPO2 level was low, brings another concern about the available gas for exchange. I mean that if this patient did not have any problem affecting gas exchange at the alveolar level, then SPO2 readings should not be affected. Mild, Moderate or Sever cases of Co Poisoning would have not affected SPO2 readings, as the Pulse Oximeter reads how well the HG Molecules are saturated but regardless of the tyoe of molecule that is being carried.

I do not want to rely on SPO2 only, again I was not there and the patient could have been mildly hypothermic and this is why SPO2 was low. I do not know, I am only giving all my thoughts, so I make sure I did not leave a possibility.

If the Pt. Temp was fine, I would sort of lean toward a possible perfusion problem at the alveolar level.

This brings another question to the table, Does CO poisoning play a role in developing mild Pulmonary Edema? Does it have any affect on Capillary Permiability?

There was an interesting study done about CO Poisoning and Developing Mild Left Ventricular Dysfunction. This study concluded that moderate to severe cases of CO Exposure could cause LVD without the presence of any previous history of Cardiac Diseases. Could a mild LVD in this case,have been a contribute cause of the Low Spo2 reading, keeping in mind that LOW SPO2 means neither the CO nor the Oxygen is being saturated very well as a possible casue of inadequate gas exchange at the alveolar - capillary level? I am not really sure but it is a certain possibility.

Again, thank you for sharing this with us. It is very interesting, and sure opening our minds to many possibilities.

[Novisen]

http://www.masimo.com/pdf/whitepaper/CO-ED&EMS.PDF

http://www.masimo.com/rad-57/index.htm

[DwayneEMTP]

I also thought the SPO2 didn't differentiate between CO and H2O, that it would read high.

Good God. I actually typed that? :shock:

The heroin must not have been completely out of my system yet...

And you all let it go by without a beating?! Man, you're slipping! :wink:

Dwayne

[AZCEP]

Carboxyhemoglobin (CO) and methemoglobinemia (H2O) are both causes of false high pulse oximetry readings. Why would you expect a beating for bringing another cause of the problem to light?

[DwayneEMTP]

Hell, I must have looked that up when we talked about this before.

I thought I was referring to water when I reread it... :oops:

Dwayne

[VentMedic]

H2O is water.

HO2 is a perhydroxyl - free radicals when referring to Nitric Oxide (NO) which we use alot in the ICUs. Methemoglobinemia is a concern with NO.

CO-OX measurements which the SpO2 does not differientate:

MetHb - methemoglobin or MHb (occassionally)

COHb - Carboxyhemoglobin

O2Hb - Oxyhemoglobin

HHb - Deoxyhemoglobin

tHb - total hemoglobin

The RAD-57 is a nice piece of equipment but very expensive. You can also get one to read MetHb as well as COHb which is of course more expensive.

Some medications can cause a non-invasive COHb monitor to read falsely high also. Of course, high readings should be followed by a blood CO-OX measurement.