# Pulse Ox?



## AShaddeau (Mar 7, 2013)

Is this correct? Wouldn't you use a BVM for a pt that is having difficulty breathing? 

3.Apply oxygen devices as you normally would without the benefit of a pulse oximeter reading.
Patients who exhibit difficulty breathing, or any signs of circulatory difficulty, should receive high-flow oxygen via non-rebreather mask, regardless of oxygen saturation readings.  :unsure:

http://www.wmems.org/pulseox.html


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## STXmedic (Mar 7, 2013)

I'm not exactly sure what you're asking.... Could you rephrase it a little better?


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## EpiEMS (Mar 7, 2013)

AShaddeau said:


> Is this correct? Wouldn't you use a BVM for a pt that is having difficulty breathing?



The difference between difficulty breathing and apneic in need of positive pressure ventilation could be boiled down to this: if they can't breathe on their own, BVM. If they're breathing, but, say, have difficulty breathing (i.e. are saying "I can't breathe"), an NRB would be indicated.

This being said, you can (and ought to) ventilate (with a BVM) a patient who is breathing but less than 8 or more than 24 respirations per minute.

Pulse oximetry is a tool -- don't ignore the patient. If the patient says they're having trouble breathing but the SpO2 is 99%, they very well may be having a problem -- consider O2.

NB: Pulse ox is not always accurate: think Cyanide poisoning, say.
NB (2): Remember that it is NOT a measure of respiratory status, not fully, it only measures oxygenation.


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## WTEngel (Mar 7, 2013)

Depends on the level of respiratory distress. Some patients need some ventilatory assistance if their rate or depth is inadequate and they don't appear able to maintain adequate ventilation on their own.

Essentially what the paragraph you quoted is saying is "treat the patient, not the SPO2 monitor." Given the information in that paragraph, the opposite argument could be made for patients showing low or normal SPO2 readings, yet lack outward signs and symptoms. That is to say, patent are not required to get oxygen simply by virtue of having an ambulance arrive at their home. The decision should be made based on clinical observations, which may or may not include SPO2 readings.

So if you want a terribly simplistc overview of the concept, for which their are likely multiple exceptions, here you go:

Use an NRB, NC, or other non-assisting device for patients who can breathe,(ventilate) but are not oxygenating well.

Use a BVM and adjuncts if appropriate and necessary for patient who can't ventilate.


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## Frozennoodle (Mar 7, 2013)

AShaddeau said:


> Is this correct? Wouldn't you use a BVM for a pt that is having difficulty breathing?
> 
> 3.Apply oxygen devices as you normally would without the benefit of a pulse oximeter reading.
> Patients who exhibit difficulty breathing, or any signs of circulatory difficulty, should receive high-flow oxygen via non-rebreather mask, regardless of oxygen saturation readings.  :unsure:
> ...



There are many different levels of, "Difficulty breathing." One the one hand you have the asthmatic might be managing his asthma fine but has since run out of his nebulized medications. He becomes anxious, dials 911, and may have some mild wheezing. Is he short of breath? Absolutely. Does he need to be bagged? Nah. He's 126/78 RR 22 no accessory muscle use noted. Maybe your protocols allow for you to throw him on a breathing treatment and he clears right up. A BVM would be overkill here and wouldn't fix the reactive airway. The patient needs a beta agonist to open up his airways. 

Then on the opposite end of the spectrum you have a 65 year old male with SOB x1 day, lower extremity edema, distended abdomen, 240/145 HR125 BP 40RR bilateral wheezes and crackles throughout, tripodding, and using accessory muscles. This guy is really short of breath and could use some positive pressure ventilation.  

It's all about your assessments. That's what this is trying to get across. The pulse ox is a tool but without knowing his o2 sat you can see the difference between the critical CHF patient and the asthmatic in mild distress. Sometimes the pulseox is wrong or reads a normal reading. It's those times where you have to look at the patient as a health care provider and think, "Ok, is he in distress or not and what do I have to do to fix it?"


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## AShaddeau (Mar 7, 2013)

Thanks for clearing that up! I appreciate the help.


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## WTEngel (Mar 7, 2013)

Frozennoodle said:


> There are many different levels of, "Difficulty breathing." One the one hand you have the asthmatic might be managing his asthma fine but has since run out of his nebulized medications. He becomes anxious, dials 911, and may have some mild wheezing. Is he short of breath? Absolutely. Does he need to be bagged?



Interesting side not on this scenario...this patient likely would not benefit from bagging, and it may exacerbate the issue. Asthmatics have lower airway obstruction issues, and hence trap air. 

Asthmatics have trouble exhaling, not inhaling.


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## truetiger (Mar 7, 2013)

The pulse ox does not measure tissue perfusion, it measures the saturation of one red blood cell. If you have a low spo2 and labored breathing, treat accordingly. If you have a high spo2 and labored breathing, treat the patient, not the number, if you have a high spo2 and no cyanosis/complaints of shortness of breath, safe to say you're ok.


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## Frozennoodle (Mar 7, 2013)

WTEngel said:


> Interesting side not on this scenario...this patient likely would not benefit from bagging, and it may exacerbate the issue. Asthmatics have lower airway obstruction issues, and hence trap air.
> 
> Asthmatics have trouble exhaling, not inhaling.



I was going to add that in but was having trouble framing it in my head so I just skipped it. Thanks!


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## emsdude89 (Mar 7, 2013)

*Good thoughts*

Where I work, we all seem to call it "O2 sat" and not "pulse ox" must be an Indiana thing.


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## systemet (Mar 7, 2013)

> This being said, you can (and ought to) ventilate (with a BVM) a patient who is breathing but less than 8 or more than 24 respirations per minute.



I think that this only holds true for testing scenarios.  In real world situations the decision to ventilate is usually base on depth and level of consciousness.  

I've had plenty of adults with resps in the 30s or higher who've been alert and moving decent volumes. BVM assisted ventilation is quite difficult without sedation, and carries its own risks.


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## Mariemt (Mar 8, 2013)

emsdude89 said:


> Where I work, we all seem to call it "O2 sat" and not "pulse ox" must be an Indiana thing.



A "pulse Oximeter " reads "O2 Saturation"

I am digging the quotes


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## JPINFV (Mar 8, 2013)

Mariemt said:


> A "pulse Oximeter " reads "O2 Saturation"
> 
> I am digging the quotes


Corrections. a pulse oximeter measures oxygen saturation. 


Side question... why is "pulse oximeter" in quotes?


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## truetiger (Mar 8, 2013)

Has anyone seen the new "pulse ox like" device that reads svo2?


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## Mariemt (Mar 8, 2013)

JPINFV said:


> Corrections. a pulse oximeter measures oxygen saturation.
> 
> 
> Side question... why is "pulse oximeter" in quotes?


Semantics

I don't know I was just following the lead. We all shall use quotes.


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## Achilles (Mar 8, 2013)

Mariemt said:


> A "pulse Oximeter " reads "O2 Saturation"
> 
> I am digging the quotes



This is not entirely true. An Pulse Oximeter is measuring the hemoglobin content, it can not determine whether it is Carbon-monoxide or Oxygen. CO has an affinity 250 greater than O2.


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## JPINFV (Mar 8, 2013)

ffjosh said:


> This is not entirely true. An Pulse Oximeter is measuring the hemoglobin content, it can not determine whether it is Carbon-monoxide or Oxygen. CO has an affinity 250 greater than O2.



It's measuring hemoglobin saturation... not hemoglobin content (that would be a CBC).


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## BeachMedic (Mar 8, 2013)

Get an EtcO2 in conjunction with SpO2. Or just go with the EtCo2 instead. I like it more.


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## STXmedic (Mar 8, 2013)

BeachMedic said:


> Get an EtcO2 in conjunction with SpO2. Or just go with the EtCo2 instead. *I like it more.*


Best rationale ever. Don't even use pulse oximetry. I don't like it.


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## BeachMedic (Mar 8, 2013)

PoeticInjustice said:


> Best rationale ever. Don't even use pulse oximetry. I don't like it.



I can't tell if I am being mocked or agreed with. lol


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## STXmedic (Mar 8, 2013)

BeachMedic said:


> I can't tell if I am being mocked or agreed with. lol



Yes. 

:unsure:


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## BeachMedic (Mar 8, 2013)

PoeticInjustice said:


> Yes.
> 
> :unsure:



Either way I stand by my original statement!

Pulse oximetry is a lie! Sometimes.

That and I hate worrying about things like cold fingers, nail polish remover, calluses, and feces fingers.


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## NomadicMedic (Mar 8, 2013)

I think a pulse ox (with a good pleth), in conjunction with side stream ETCO2 will give you a pretty good indication of a Patients oxygenation and ventilatory status. I make it a habit to use both when there's any question.


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## Haley124 (Mar 8, 2013)

Nebraskas protocol is every patient should get Oxygen for difficulty breathing, regardless of pulse ox reading. 

Pulse ox readings can read wrong for carbon monoxide posioning. So you are never 100% sure.


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## STXmedic (Mar 8, 2013)

Haley124 said:


> Nebraskas protocol is every patient should get Oxygen for difficulty breathing, regardless of pulse ox reading.
> 
> Pulse ox readings can read wrong for carbon monoxide posioning. So you are never 100% sure.



Are you under the assumption that all of your patients have CO toxicity?...

You have come to the right place, young one. Please, open your ears and allow us to pass our wisdom unto you


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## Mariemt (Mar 9, 2013)

Haley124 said:


> Nebraskas protocol is every patient should get Oxygen for difficulty breathing, regardless of pulse ox reading.
> 
> Pulse ox readings can read wrong for carbon monoxide posioning. So you are never 100% sure.



We titrate our O2 as much as possible. Especially chest pain. 
Carbon monoxide, O2 for sure, wont get an accurate reading with a regular pulse ox.


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## DesertMedic66 (Mar 9, 2013)

PoeticInjustice said:


> Are you under the assumption that all of your patients have CO toxicity?...
> 
> You have come to the right place, young one. Please, open your ears and allow us to pass our wisdom unto you



All of my patients do seem to have CO poisoning...


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## usalsfyre (Mar 9, 2013)

BeachMedic said:


> Get an EtcO2 in conjunction with SpO2. Or just go with the EtCo2 instead. I like it more.



It's not an either/or, they tell you about two completely different functions. Entirely possible to be hypoxic with perfect EtCO2 and give versa. 

Plus if you know about alveolar status and cardiac output you'll realize that EtCO2 can be just as much of a lie.


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## Mariemt (Mar 9, 2013)

:unsure:





firefite said:


> All of my patients do seem to have CO poisoning...


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## BeachMedic (Mar 9, 2013)

usalsfyre said:


> It's not an either/or, they tell you about two completely different functions. Entirely possible to be hypoxic with perfect EtCO2 and give versa.
> 
> Plus if you know about alveolar status and cardiac output you'll realize that EtCO2 can be just as much of a lie.




I know, "they tell you about two completely different functions."

If I had to choose one i'd still take EtCO2 (with waveform) over SpO2 every day of the week. Heck, I'd rather go without SpO2 all together and just go with skin signs and respiratory rate. I don't think pulse oximetry is the most useful tool in the world and I feel too many people are entirely too dependent on it. I use it but I've also had to make due without it plenty of times. Sometimes for the reasons I've stated above, and other times because it seems like pulse ox extensions break and decide to stop reading fairly frequently.

You win the one up contest though. I owe you a super mario t-shirt. I don't know how alveolar status and cardiac output affect EtCO2 readings(causing false positives). Aside from being a useful tool for measuring the quality of CPR and jumps in EtCO2 indicating possible ROSC. Feel free to enlighten me. It hasn't been taught in any of the curriculum I've been presented.


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## truetiger (Mar 9, 2013)

In the presence of low CO, you'll get false low values. IE your EtCO2 could be say 20 yet your PaC02 could be much higher. You're lacking the cardiac output to move the CO2 to the lungs for removal.


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## usalsfyre (Mar 9, 2013)

BeachMedic said:


> I know, "they tell you about two completely different functions."


Then why are we discussing them in a one or the other fashion? It's like saying you can have a 12 lead or labs, but not both. You're not alone in this, I've heard a lot of people make this statement. 



BeachMedic said:


> If I had to choose one i'd still take EtCO2 (with waveform) over SpO2 every day of the week. Heck, I'd rather go without SpO2 all together and just go with skin signs and respiratory rate.


Had a patient last night, palish centrally. Normal respiratory rate, not a particularly increased work of breathing. SpO2 was in the mid 80s. Switched to a mask from a NC and his sats jumped to the mid 90s. Looking at this guy you never would have guessed his sats were that low. Another situation, we have established that giving oxygen to pt's having STEMIs causes increased oxidative damage. Every STEMI I've seen looked like they needed O2, but the vast majority were not hypoxic. Without SpO2 I wouldn't have known that. 




BeachMedic said:


> I don't think pulse oximetry is the most useful tool in the world and I feel too many people are entirely too dependent on it.


Glad you feel that way. Pretty much the rest of medicine disagrees about its utility.  



BeachMedic said:


> I use it but I've also had to make due without it plenty of times. Sometimes for the reasons I've stated above, and other times because it seems like pulse ox extensions break and decide to stop reading fairly frequently.


Making due without because it breaks is not the same as saying "its not useful, I could easily do without it".  



BeachMedic said:


> You win the one up contest though. I owe you a super mario t-shirt.


Passive agressiveness....awesome 




BeachMedic said:


> I don't know how alveolar status and cardiac output affect EtCO2 readings(causing false positives).


So you admit you don't know about the limitations of this particular tool, but its worse than SpO2? 

Think about WHY you get that EtCO2 jump post arrest. The EtCO2 reading may have nothing to do with overventilating a patient, it may have everything to do with the fact that your patient isn't getting enough of the products of metabolism back to their lungs to actually breathe them out (hypotension). Alveolar status is important because if the alveoli are full of junk, CO2 isn't going to diffuse out very well. The PaO2 to EtCO2 gradient is an important thing to know when evaluating the quality of your EtCO2 reading, but its not something your going to know without a blood gas. Also explore the dilution effect that occurs when its being used on anything other than an ETT. 



BeachMedic said:


> Aside from being a useful tool for measuring the quality of CPR and jumps in EtCO2 indicating possible ROSC. Feel free to enlighten me. It hasn't been taught in any of the curriculum I've been presented.


It hasn't been taught because the people teaching likely didn't know. EtCO2 has NOT been explained well to the majority of medics. It's sold as a silver bullet when the fact is its not.


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## BeachMedic (Mar 9, 2013)

Done thread hijacking. Sending PM.


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## Carlos Danger (Mar 10, 2013)

For all _practical_ purposes in the field, Etc02 and Sp02 tell you pretty much the same thing: is the patient ventilating & exchanging gas well enough to meet metabolic demands, or not?

A patient who is exchanging gas poorly can often have their oxygen demand met by the administration of high-flow oxygen. Which is exactly why the NRB is such a staple of EMS care. High-flow O2 is a very blunt instrument, and there are times when it won't help or when it could (rarely) even hurt, but much more often than not, high-flow oxygen during transport will do far more good than harm. 

I would much rather see people giving oxygen unnecessarily, than withholding it from people who need it based on an incomplete understanding of gas exchange physiology and poor interpretation of Etco2 waveforms. There are lots of things that affect the serum pH. 

Other than confirming ETT placement and monitoring ventilation in an intubated patient, I can't think of much utility for Etc02 in the prehospital arena. Sure there are times when it may be nice to have, but I just can't think of many instances in which it would actually change treatment.


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## truetiger (Mar 10, 2013)

Nope, not even close. Here's an example. We have a pt we run frequently that calls for sob. She has a hx of chf and copd among other things. Many times the crew will just roll out there, put her on the pulse ox, and get a reading of 100, leave her on nrb, and say she's fine. If you don't put her on etco2, you can't gauge how sick she actually is. She'll be in ventilatory failure with a pa02 100+. You're just pissing in the wind with your nrb mask. This pt works very hard to maintain that 100%, but it'll get dismissed as anxiety. She'll eventually tire and require intubation in the hospital. By using both tools, and understanding them, intubation and respiratory acidosis can be avoided in the pt.


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## Carlos Danger (Mar 10, 2013)

truetiger said:


> Nope, not even close. Here's an example. We have a pt we run frequently that calls for sob. She has a hx of chf and copd among other things. Many times the crew will just roll out there, put her on the pulse ox, and get a reading of 100, leave her on nrb, and say she's fine. If you don't put her on etco2, you can't gauge how sick she actually is. She'll be in ventilatory failure with a pa02 100+. You're just pissing in the wind with your nrb mask. This pt works very hard to maintain that 100%, but it'll get dismissed as anxiety. She'll eventually tire and require intubation in the hospital. By using both tools, and understanding them, intubation and respiratory acidosis can be avoided in the pt.



And the Etco2 changes your care of this patient exactly how?


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## truetiger (Mar 10, 2013)

By being super aggressive in improving her ventilation. Bronchodilators, steroids, etc.


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## Aidey (Mar 10, 2013)

Or earlier intubation.


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## DrankTheKoolaid (Mar 10, 2013)

This is exactly why continuing education should be just that. And not just taking the same crap card courses over and over and in house training on the same subjects year after year


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## Brandon O (Mar 10, 2013)

The sense to viewing pulse oximetry as a nigh-vital sign is that it's a physiologic endpoint. Many things contribute to maintaining that sat, and if you only consider the endpoint you can totally fail to account for those compensatory or pathological processes, but nevertheless it's valuable and irreplaceable insofar as endpoints like that (or blood pressure, for instance) are always important.

Is end-tidal capnography the same? Yes, but it combines several endpoints (cellular metabolism, pulmonary exchange, ventilatory adequacy, pH, etc.) into one number and one waveform, which makes it both powerful and less immediately clear.


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## Carlos Danger (Mar 10, 2013)

truetiger said:


> By being super aggressive in improving her ventilation. Bronchodilators, steroids, etc.


That didn't answer my question at all.

What I would like to know is, how does having an Etc02 _change _your treatment?



truetiger said:


> We have a pt we run frequently that calls for sob. She has a hx of chf and copd among other things. Many times the crew will just roll out there, put her on the pulse ox, and get a reading of 100, leave her on nrb, and say she's fine. *If you don't put her on etco2, you can't gauge how sick she actually is. She'll be in ventilatory failure with a pa02 100+.* You're just pissing in the wind with your nrb mask. *This pt works very hard to maintain that 100%,* but it'll get dismissed as anxiety. She'll eventually tire and require intubation in the hospital. By using both tools, and understanding them, intubation and respiratory acidosis can be avoided in the pt.



Let me get this straight....

Are you saying that if you have a patient with a history of CHF and COPD, who presents with increased work of breathing and complaints of shortness of breath, that you need an Etc02 to decide whether or not to treat her?



truetiger said:


> If you don't put her on etco2, you can't gauge how sick she actually is.


This is 100% false. The clinical presentation is far more important than the Etc02 or Sp02 readings.

An Etc02 reading, like most objective measurements, is simply a snapshot in time. It's useful for trending, but that's about it.

Would you really not treat a patient in obvious respiratory distress, just because their Etc02 was normal?

Would you aggressively treat a patient whose Etc02 was abnormal, even if they were breathing just fine?


There are many things that can affect an Etc02. If you have a low CO or a shunt (neither of which are unlikely in a CHF patient), you can have a normal or near-normal Etc02 and be nearing respiratory failure. Or you can have an abnormal Etc02 and be fine, respiratory-wise, if the origin is metabolic. In some severe cases of metabolic acidosis, intubation can prove fatal since it's difficult with a mechanical ventilator to match the minute volume that a spontaneously-breathing patient achieves. 

Without a blood gas, you are just guessing, especially in a patient with a complex history.

It's far better to base your treatments on clinical presentation.

I believe that as a snapshot in time, Sp02 is a better reflection of the criticality of a patient's condition.


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## JPINFV (Mar 10, 2013)

Brandon Oto said:


> The sense to viewing pulse oximetry as a nigh-vital sign is that it's a physiologic endpoint. Many things contribute to maintaining that sat, and if you only consider the endpoint you can totally fail to account for those compensatory or pathological processes, but nevertheless it's valuable and irreplaceable insofar as endpoints like that (or *blood pressure*, for instance) are always important.




So what you're saying is that if we don't like the blood pressure number, we should disregard it and bolus them anyways? Therefore, blood pressures are useless. Treat the patient... not the number... and all that jazz...


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## Aidey (Mar 10, 2013)

old school said:


> I believe that as a snapshot in time, Sp02 is a better reflection of the criticality of a patient's condition.



Actually, since EtCO2 also displays whether or not the patient is breathing I think it might have a slight edge on showing how sick the pt is. Not breathing tends to be one of those critical condition things.


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## Brandon O (Mar 11, 2013)

JPINFV said:


> So what you're saying is that if we don't like the blood pressure number, we should disregard it and bolus them anyways? Therefore, blood pressures are useless. Treat the patient... not the number... and all that jazz...



:glare:

I sayin' that while a lot of factors go into a number like BP or O2 saturation... and if you're using it as your sole marker to dictate care, you're going to be tragically behind the 8-ball in many cases, because in compensating patients they are often the LAST thing to change... and they are, at best, sensitive yet totally unspecific for severe illness... nevertheless they are important.

The air gauge on a diver's tank is important for the same reason. If you're using that as your only means of guiding your dive, you're a total ninny, but still -- ya want to know, don't ya?


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## JPINFV (Mar 11, 2013)

Brandon Oto said:


> :glare:



Problem?
h34r:


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## systemet (Mar 11, 2013)

old school said:


> It's far better to base your treatments on clinical presentation.
> 
> I believe that as a snapshot in time, Sp02 is a better reflection of the criticality of a patient's condition.



I like these statements.  

I think the numbers become an objective measurement that support the clinical diagnosis.

In the COPD patient, you're not usually intubating because the pO2 is low, or the PaCO2 is high.  You're generally intubating because there's signs of impending decompensation, i.e. that the patients work of breathing is decreasing or that their level of consciousness is deteriorating (an indirect measure that PaCO2 is going up).

A PETCO2 doesn't always correlate well with PaCO2, especially when there's lung pathology involved.  True, the PaCO2 is usually at least as high as PETCO2, but it can be substantially higher.  The PETCO2 can make the patient look better than the PaCO2 does.

This particular subset of patients may have chronically elevated PaCO2.  So at what point do we decide this PETCO2 is abnormal for them?  An ABG gives you a PaCO2, and a pH and bicarbonate that help you determine whether this is an acute change.

In a healthier person, like a 19 year old you've just sedated, or the heroin overdose you're monitoring, but are holding back on giving narcan to, number like a PETCO2 of 50 mmHg take on a little more meaning.  If a COPDer has a high PETCO2, but is oxygenating ok, maintaining their respiratory effort, and is alert, then we're not thinking advanced airway yet, right?

I guess my long and rambling point is that the ETCO2 is an adjunct to a physical examination, a relatively minor part of the clinical picture and is not always reliable.


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