Pulse CO-Oximeter

[Remember585 815]

I was thumbing through the pages of the new December 2005 Firehouse Magazine and came across an advertisement for this unit. I have to say that it sparked my interest, so I went to the website to read more about it.

Those of you in the fire service are bound to be familiar with the ever-present risk of CO during firefighting operations. I know that over the years I've not only seen brothers feeling the effects after a fire, but have also felt it myself. It would be nice to see those in the rehab sector utiliing these units to help treat someone more "appropriately" then guessing if CO is an issue.

Obviously, just because we have this kind of device out there now, it doesn't mean we can drop our masks and wait and see how high our carboxyhemoglobin levels can get....

Here's the link - Masimo SET Rad-57

Any thoughts? Personally I would like to not only see my FD get these for our rehab ops, but I'd like to look into them at my VAC as well. And not just for fire scenes but at those CO incidents we run every year.

Not to drift too far off topic, but I am also a believer in purchasing a CO meter to clip onto EMS bags to warn personnel of possible situations we may not be aware of.

[antiquefirelt 994]

We just had a demo of the Massimo unit. It seems to work well and is the only thing out there like it. We will be getting one this Jan and maybe a second in June. The thought is that we often cannot get occupants to seek medical attention after being exposed to CO in there buildings. WE had to argue with a pregnant woman for over a half hour after she was in an apt. where the readings were over 200 PPM. Also will be used in FF Rehab. This might create a real issue if we all have been operating at higher than normal levels and now have to make many people sit out. Still it seems like the right thing given the cold winter and high fuel prices will force people to "tighten" there homes even more, increasing the risk of CO exposure. By the way the unit is $3000.00 or $2500 if you trade in a SPO2 monitor, which this also does.

And as you believe, we just bought 5 single gas CO monitors for our EMS units to have on all jump bags, just to see. I think we'll see some CO issues vs. the old general weakness or "flu-like" sypmtoms.

Edited December 15, 2005 by antiquefirelt

[roeems87 0]

I'm curious about a few things...

Just based on the website that is in the link about, take a look at the graph showing the results... Those "best fit" lines don't seem to be entirely accurate. If any, only the top one seems to be correct. If you take a look at some of the data points, they are relatively (extremely) high compared to the actual reading taken from the blood gas...

It's fine if you obtain this reading and on scene (and especially in the transport decision) this will help to know what's going on with your patient; HOWEVER, there is no way the hospital will ever act on such a reading... That said, the type of treatment they will render will depend on the blood gas they are going to get anyway (and would get anyway with the given symptoms). I guess the only real benefit would be in deciding what hospital you may be transporting to (and convincing someone they need to go) and who needs rehab (in the case of internal use). I'm wary of it's use though when lots of the readings shown on that website seem to be abnormally high...

Lastly, how does this thing work? A pulse oximeter is a colorimetric device... I'm curious how the CO version will work. One of the false positives you get with the PO2 is in the case of CO poisoning. You will get a 100% or close to it (i.e. a nearly perfect reading) when the patient in fact is binding and perfusing CO and nothing else (or very little O2). It appears to have the same finger probe as the PO2 has, but I am curious how this thing works... If anyone knows, I would like to understand it... If it really does work effectively, then perhaps this is the next level of technology in pulse-oximetry as well. If it can tell what's CO and what's O2, then perhaps many of the false positives with PO2 (some others included) can also be eliminated...

[Skooter92 7]

From http://www.nda.ox.ac.uk/wfsa/html/u05/u05_003.htm:

"How does an oximeter work? A source of light originates from the probe at two wavelengths (650nm and 805nm). The light is partly absorbed by haemoglobin, by amounts which differ depending on whether it is saturated or desaturated with oxygen. By calculating the absorption at the two wavelengths the processor can compute the proportion of haemoglobin which is oxygenated. The oximeter is dependant on a pulsatile flow and produces a graph of the quality of flow. Where flow is sluggish (eg hypovolaemia or vasoconstriction) the pulse oximeter may be unable to function. The computer within the oximeter is capable of distinguishing pulsatile flow from other more static signals (such as tissue or venous signals) to display only the arterial flow."

The CO portion of the device works in a similar fashion, using different wavelengths. Since it uses 8 different wavelengths to detect different saturated gases, the incidence of false positives is probably decreased by a major margin.

Edited December 15, 2005 by Skooter92

[Guest]

I'm curious about a few things...

Just based on the website that is in the link about, take a look at the graph showing the results... Those "best fit" lines don't seem to be entirely accurate. If any, only the top one seems to be correct. If you take a look at some of the data points, they are relatively (extremely) high compared to the actual reading taken from the blood gas...

It's fine if you obtain this reading and on scene (and especially in the transport decision) this will help to know what's going on with your patient; HOWEVER, there is no way the hospital will ever act on such a reading... That said, the type of treatment they will render will depend on the blood gas they are going to get anyway (and would get anyway with the given symptoms). I guess the only real benefit would be in deciding what hospital you may be transporting to (and convincing someone they need to go) and who needs rehab (in the case of internal use). I'm wary of it's use though when lots of the readings shown on that website seem to be abnormally high...

Lastly, how does this thing work? A pulse oximeter is a colorimetric device... I'm curious how the CO version will work. One of the false positives you get with the PO2 is in the case of CO poisoning. You will get a 100% or close to it (i.e. a nearly perfect reading) when the patient in fact is binding and perfusing CO and nothing else (or very little O2). It appears to have the same finger probe as the PO2 has, but I am curious how this thing works... If anyone knows, I would like to understand it... If it really does work effectively, then perhaps this is the next level of technology in pulse-oximetry as well. If it can tell what's CO and what's O2, then perhaps many of the false positives with PO2 (some others included) can also be eliminated...

←

Roe,

Based on my admittedly brief research it appears that a standard pulse oximtery unit only uses 2 distinct wavelengths of light, while this unit (at least from what the company's website claims) uses 8, the increased number of wavelengths would allow you to get more data, and I'm presuming that they can interpret the reflected, refracted, and absorbed wavelengths to gather more data about the chemicals in the blood. They also claim that they are using new signals processing algorithms and such to enhance the data (something I should be able to speak a little more intelligently on in a semester or two).

As far as the accuracy, the center best fit line I think is what the average performance point was, and the other two lines, I think, represent the +/- 3% accuracy that they quote below the graph. If you click here (http://masimo.com/Rainbow/rb-overview.htm) they state that they are FDA-cleared ti accurately measure blood CO levels (whatever that means). However just by looking at the graph I'd say at most 5-10% of those points are outside of the range and the graph is deceptive in that there may be more actual tests done than we can discern (for instance in those clusters), which means the number of outliers is probably 5% or less which is pretty good for lab work (from what I'm told). It also appears that the vast majority of the outliers are on the high side, which I think would be better than them being on the low side. On a BLS level if we suspect CO exposure won't we be treating them the same regardless of what this thing says?

My thinking is this: its a tool, and like every tool it has an uncertainty and its uses. Sorry for the spiel.

Edited December 15, 2005 by JaredHG