# O2 in ACS



## Av8or007 (Oct 21, 2011)

I am an Advanced medical first responder (basically a Canadian version of an EMT-B). The 2010 guidelines state that you do not give uncomplicated ACS pts o2 unless they are hypoxic (SpO2 <94%) or dyspnea is present.

If I do not normally have access to a pulse ox, when should I give O2 (other than hypoxia or prior to a "procedure" involving the resp tract? 

If you have a pulse ox them titrate to >= 94%?


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## Handsome Robb (Oct 21, 2011)

Are they cyanotic? Are they breathing adequately? How's their mentation? How's their work of breathing? Lung sounds? Is the patient complaining about not being able to catch their breath?

Pulse Oxs can be wrong too, its just another tool.


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## Av8or007 (Oct 21, 2011)

Thanks

Good points, check em and if there is an issue put the pt on O2.

"Pulse Oxs can be wrong too, its just another tool."

-Treat the patient NOT the monitor!!!


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## Handsome Robb (Oct 21, 2011)

Av8or007 said:


> -Treat the patient NOT the monitor!!!



We have a winner!


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## usalsfyre (Oct 21, 2011)

NVRob said:


> We have a winner!



Arggghhh, no!!!

The only reason this phrase exist is because of the heap of paramedics who are not educated enough to clinically correlate the information the monitor presents.

If I'm not using the monitor to base treatment decisions of of, why am I lugging 15+ pounds of extra kit around?


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## fast65 (Oct 21, 2011)

usalsfyre said:


> Arggghhh, no!!!
> 
> The only reason this phrase exist is because of the heap of paramedics are not educated enough to clinically correlate the information the monitor presents.
> 
> If I'm not using the monitor to base treatment decisions of of, why am I lugging 15+ pounds of extra kit around?



I do it because the cool beeping sounds entertain me, there are other reasons?


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## Handsome Robb (Oct 21, 2011)

usalsfyre said:


> Arggghhh, no!!!
> 
> The only reason this phrase exist is because of the heap of paramedics who are not educated enough to clinically correlate the information the monitor presents.
> 
> If I'm not using the monitor to base treatment decisions of of, why am I lugging 15+ pounds of extra kit around?



Fair enough. I agree. 

You always make me feal dumb, geez usals!


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## JPINFV (Oct 21, 2011)

fast65 said:


> I do it because the *cool beeping sounds *entertain me, there are other reasons?


[youtube]http://www.youtube.com/watch?v=xuZl9tRqjoQ[/youtube]


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## usalsfyre (Oct 21, 2011)

NVRob said:


> Fair enough. I agree.
> 
> You always make me feal dumb, geez usals!



Not dumb, not dumb at all Rob, you just happened to hit a pet peeve statement of mine.

Lots of the old saws in EMS grew out of when we were a couple of hundred hour techs who didn't really know the science behind things. We've mostly grown out of those days, but the stupid sayings persist.


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## Shishkabob (Oct 21, 2011)

fast65 said:


> I do it because the cool beeping sounds entertain me, there are other reasons?



If you're stumped, you can stare intently at the screen as if trying to read something.  Need more time?  Print off a 12 and stare even more intently at that, then say something that sounds like a rhythm.


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## Handsome Robb (Oct 21, 2011)

Linuss said:


> If you're stumped, you can stare intently at the screen as if trying to read something.  Need more time?  Print off a 12 and stare even more intently at that, then say something that sounds like a rhythm.



I like it!


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## Akulahawk (Oct 21, 2011)

usalsfyre said:


> Arggghhh, no!!!
> 
> The only reason this phrase exist is because of the heap of paramedics who are not educated enough to clinically correlate the information the monitor presents.
> 
> If I'm not using the monitor to base treatment decisions of of, why am I lugging 15+ pounds of extra kit around?


That's the thing... you DON'T base your treatment around what the monitor says. You base your treatment based on the whole clinical picture, not just what's on the monitor. If you based your care solely on the monitor, we could just send out a robot to hook you up to the machine and the machine can just do it's thing... based on the sensors on board...(the monitor)

We'd get fantastic care every time!!!! :blink:


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## JPINFV (Oct 21, 2011)

Akulahawk said:


> That's the thing... you DON'T base your treatment around what the monitor says. You base your treatment based on the whole clinical picture, not just what's on the monitor. If you based your care solely on the monitor, we could just send out a robot to hook you up to the machine and the machine can just do it's thing... based on the sensors on board...(the monitor)
> 
> We'd get fantastic care every time!!!! :blink:




The problem is that "treat the patient not the monitor" is taken to the opposite extreme half the time where if the monitor doesn't match exactly what is expected, it is ignored.


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## Akulahawk (Oct 21, 2011)

JPINFV said:


> The problem is that "treat the patient not the monitor" is taken to the opposite extreme half the time where if the monitor doesn't match exactly what is expected, it is ignored.


Sadly enough... this is SOOOO true... and when I was an FTO, not what I taught.


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## Av8or007 (Oct 21, 2011)

The thing is that you must take both what the monitor tells you AND the clinical picture that you see into account when treating the pt. Never "ignore" a strange or unusual result on the monitor, just correlate it with the clinical picture and make Tx. decisions based off the integrated clinical picture.

"if it is a textbook case, there's nothing normal about it"
 [note: this doesn't always apply]

e.g. a pt that presents with symptoms of an MI USUALLY has chest pain and MAY have ekg changes, but it doesn't mean the patient IS/ISN'T having an MI. There's been cases that present with pain in the jaw.

The inverse is also true, and a PT that presents w/ marked ST elevation indicative of a STEMI may not actually have a STEMI, instead they may have another cond. that causes ST elevation. It takes a good care provider/medic to tell the difference.


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## ArcticKat (Oct 21, 2011)

*Linuss and USALSFYRE hard at work.*

Thanks JPINFV, I can't figure out the metacode for that.


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## JPINFV (Oct 21, 2011)

ArcticKat said:


> <iframe width="420" height="315" src="http://www.youtube.com/embed/arCITMfxvEc" frameborder="0" allowfullscreen></iframe>


[youtube]http://www.youtube.com/watch?v=arCITMfxvEc[/youtube]


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## shockinainteasy75 (Oct 26, 2011)

AHA does not say to not give that pt O2, its a suggestion that...hold ur breath....not everyone needs a NRB at 15lpm. It states that a saturation of 95% is adequate but NC at 2 wouldn't hurt. Remember, the goal in ACS is to drcrease the myocardiums oxygen demand, giving it a little more oxygen will in turn lower demand


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## usalsfyre (Oct 26, 2011)

So O2 can clear coronary blockages and decrease MvO2? Neato...


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## JPINFV (Oct 26, 2011)

Ischemia and hypoxia are not the same thing. Related, but not the same.


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## tssemt2010 (Oct 26, 2011)

symptomatic vs asymptomatic, like everyone else has said, treat your patient not the monitor or in this case the pulse ox, i have seen a pulse ox read 83% while it was resting on a car seat not hooked up to anything, so they can be wrong


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## shockinainteasy75 (Oct 26, 2011)

usalsfyre said:


> So O2 can clear coronary blockages and decrease MvO2? Neato...



Haha. No, but its part of the process, in conjunction with NTG, and pain relievers in the prehospital world. And until we start carrying heparin and start cathing people at home ill stick with the original miracle drug. Lol


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## usalsfyre (Oct 26, 2011)

Carried heparin, it's not going to clear coronary blockages either.

Look up the CaO2 equation, you'll realize how little supraphysiologic levels of O2 add. In addition, O2 does nothing to help lower MvO2. It theoretically might help meet demand, but coronary ischemia tends to be caused by other factors that won't be affected by O2. NTG has never been shown to have a true effect on outcome in AMI and pain management is just a humane effort. 

The two things you can do for these patients are aspirin and transport to a cardiac facility.


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## Shishkabob (Oct 26, 2011)

shockinainteasy75 said:


> Haha. No, but its part of the process, in conjunction with NTG, and pain relievers in the prehospital world. And until we start carrying heparin and start cathing people at home ill stick with the original miracle drug. Lol



Can you explain to me why we use NTG and analgesics in MIs?


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## JPINFV (Oct 26, 2011)

tssemt2010 said:


> symptomatic vs asymptomatic, like everyone else has said, treat your patient not the monitor or in this case the pulse ox, i have seen a pulse ox read 83% while it was resting on a car seat not hooked up to anything, so they can be wrong




So a patient who is asymptomatic, but with a SpO2 of 88, provided the displayed heart rate matches your measured pulse rate and a good waveform is present if applicable, shouldn't have supplemental oxygen started?


More importantly, we should ignore a device that measures a physiologic parameter by using light wavelengths because when it's left out and it senses light wavelengths that correspond to a specific reading, it displays the reading? What's next, we should ignore EKGs because of CPR artifact?


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## JPINFV (Oct 26, 2011)

shockinainteasy75 said:


> Haha. No, but its part of the process, in conjunction with NTG, and pain relievers in the prehospital world. And until we start carrying heparin and start cathing people at home ill stick with the original miracle drug. Lol




So oxygen, NTG, and narcotics can clear coronary blockages? Neato...


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## Shishkabob (Oct 26, 2011)

tssemt2010 said:


> symptomatic vs asymptomatic, like everyone else has said, treat your patient not the monitor or in this case the pulse ox, i have seen a pulse ox read 83% while it was resting on a car seat not hooked up to anything, so they can be wrong



Actually... as has been stated before, the monitor is a viable and important part of our assessment.

If you have no monitor or other tools, and an unconscious patient, you telling me you'll give every drug in the box hoping it works?  Or would you want to utilize the monitor to make a better diagnosis?




JPINFV said:


> So a patient who is asymptomatic, but with a SpO2 of 88, provided the displayed heart rate matches your measured pulse rate and a good waveform is present if applicable, shouldn't have supplemental oxygen started?


  Depends... hx of COPD or other disease?  88% COULD be their baseline...    Granted, I don't like 88%, but that's not the question


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## JPINFV (Oct 26, 2011)

Linuss said:


> Can you explain to me why we use NTG and analgesics in MIs?



At least with analgesics...

[youtube]http://www.youtube.com/watch?v=gRdfX7ut8gw[/youtube]


Side note: looking at the Evidence Based Protocols website, there's more evidence for nitrates that I thought there was.


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## tssemt2010 (Oct 26, 2011)

JPINFV said:


> So a patient who is asymptomatic, but with a SpO2 of 88, provided the displayed heart rate matches your measured pulse rate and a good waveform is present if applicable, shouldn't have supplemental oxygen started?
> 
> 
> More importantly, we should ignore a device that measures a physiologic parameter by using light wavelengths because when it's left out and it senses light wavelengths that correspond to a specific reading, it displays the reading? What's next, we should ignore EKGs because of CPR artifact?



supplemental yes but i wouldnt jump straight to 15lpm


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## Shishkabob (Oct 26, 2011)

JPINFV said:


> At least with analgesics...



What, nothing to do with decreasing pain which leads to decreasing catecholamine release leading to decreased blood pressure, heart rate and oxygen demand on the heart? :unsure:


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## JPINFV (Oct 26, 2011)

tssemt2010 said:


> supplemental yes but i wouldnt jump straight to 15lpm



Why start supplemental oxygen at all (no one said anything about a NRB) if the patient is asymptomatic and being symptomatic was the only thing that matters? After all, what if the pulse ox was wrong!


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## JPINFV (Oct 26, 2011)

Linuss said:


> What, nothing to do with decreasing pain which leads to decreasing catecholamine release leading to decreased blood pressure, heart rate and oxygen demand on the heart? :unsure:




...and trendelenburg results in autotransfusion. 



http://emergency.medicine.dal.ca/ehsprotocols/protocols/LOE.cfm?ProtID=144#Analgesia%20%28iv%20narcotic%29

To add, AHA ranks analgesia as class I (benefit >>> harm), but with a level of evidence of C (expert opinion).

In other words, analgesia works because we said so.


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## Shishkabob (Oct 26, 2011)

Meh, I'm off to a hibachi restaurant, but I'll have to hunt down the few studies I've read of it.


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## shockinainteasy75 (Oct 26, 2011)

supplemental O2 can help meet the demands of the myocardium, in turn, decreasing demand (lehmans: supply vs. demand). NTG, vasodialates increasing blood flow (however little it may be) past the blockage increasing coronary perfusion. Aspirin can help re-perfuse and analgesics are not humane in nature, we shoot dogs who are in pain, thats humane, the analgesics serve to lower anxiety levels and vasodialate (we use Morphine in MD). Lowered anxiety levels equate to potentially lower BP, in turn, once again decreasing myocardial O2 demands. I agree, the best treatment is a diesel bolus and bright lights and cold steel but if thats all were gonna due, just make ACS calls BLS and save the ALS units for uncontrollable epistaxis.


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## STXmedic (Oct 26, 2011)

shockinainteasy75 said:


> supplemental O2 can help meet the demands of the myocardium, in turn, decreasing demand (lehmans: supply vs. demand).


We're talking physiology, not economics. If their hemoglobin is already 100% saturated, how is blowing more O2 in their face going to satisfy the demand of the heart? If hemoglobin can carry "up to 4" molecules of oxygen, it's not going to magically carry six when you slap a NRB or NC on them.


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## Handsome Robb (Oct 26, 2011)

You realize how much anxiety your going to add to your patient when transporting code 3 therefore increasing their BP, HR and myocardial oxygen demand? Bad call. 

Analgesics are humane, we don't give them to reduce anxiety, we give them to reduce pain. Your correct in the fact that reduced pain reduces anxiety, I'll give you that.

Aspirin does not help re-perfuse, it is a platelet aggregator, preventing the clot from becoming larger, it does nothing to break the clot and return perfusion to the ischemic tissue.

Yea NTG might dilate the vessels, but that clot is just going to move through the dilated vessels only to get caught again as the vessels decrease in size. (Remember Arteries -> arterioles -> capillaries?) NTG does nothing to break the clot up. 

Morphine reduces pain, therefore reducing anxiety while also reducing preload by reducing venous return thus lowering the workload on the heart and myocardial oxygen demand. 

ACS is not a BLS call, can you interpret a 12 lead? STEMI alerts activated by ALS providers after reviewing a 12 lead in the field reduce door to cath-lab time and increase survivability and quality of life in ACS patients post-discharge from the hospital. 

Hyper-oxygenation constricts coronary vessels, it's a proven fact. Yea there's a high PaO2, but if the vessels are constricted then the blood with the high PaO2 can't get to the tissue what good does that do? Do some more continuing education other than the bare minimum. 

This is coming from a fellow Intermediate.


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## JPINFV (Oct 26, 2011)

PoeticInjustice said:


> We're talking physiology, not economics. If their hemoglobin is already 100% saturated, how is blowing more O2 in their face going to satisfy the demand of the heart? If hemoglobin can carry "up to 4" molecules of oxygen, it's not going to magically carry six when you slap a NRB or NC on them.



Even if hemoglobin could magically carry 6 molecules. It doesn't matter if the hemoglobin never actually gets past the occlusion.


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## Handsome Robb (Oct 26, 2011)

JPINFV said:


> Even if hemoglobin could magically carry 6 molecules. It doesn't matter if the hemoglobin never actually gets past the occlusion.



My hemoglobin is badass


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## shockinainteasy75 (Oct 26, 2011)

NVRob said:


> You realize how much anxiety your going to add to your patient when transporting code 3 therefore increasing their BP, HR and myocardial oxygen demand? Bad call.
> 
> Analgesics are humane, we don't give them to reduce anxiety, we give them to reduce pain. Your correct in the fact that reduced pain reduces anxiety, I'll give you that.
> 
> ...



A. I would kill a driver who drove like an idiot with any pt. I do not advocate that kind of transport. However i am completely honest with my pts, they know somethings wrong and by telling them the truth it takes away from the anxiety of "not knowing". 

B. You are correct in that aspirin does not dissolve a clot, however, aspirin is listed as a primary initial step under reperfusion therapy in both ACS and Ischemic stroke. In the future i will be more precise with my words.

C. When it comes to NTG, i said nothing about clot busting, it vasodialates, and even if the clot moves, we now have the chance of it moving to a more branched vessel, decreasing the area of injury/ischemia.

D. I agree with your morphine statement, 100%, i do not like the terming of humane, we treat people because they deserve the treatment, not because we feel pity for them as the word humane would suggest. 

E. Im not saying ACS should be a BLS, it was in response to an earlier statement that aspirin and trans was the only things we can do for these pts. As far as im concerned, if dispatchers (in our area) can advise pt.s to take aspirin prior to our arrival, a BLS provider should be able to. There are far more things we can do for these pt.s to improve their chances of survival. Yes, i can interpret a 12 lead, not as well as id like to be able to, but well enough to be effective. 

F. No, hyper oxyenation is not a "proven", nor "disproven" fact. Certain agencies support and others refute. That is completely up to the providers and the service area. This can go on and on involving the dispute of pulse oximeters, remembering that pulse ox's determine the % of hemoglobin saturated with something, may not always be oxygen. And even in the studies that support the ill effects of hyperoxygenation, they are quick to point out that the potential positive effects of supplemental oxygen at low concentrations out weigh the potential ill effects of this therapy. 

Please do not question my education level without knowing, nor speaking with me. I dont not claim to know half of what most people in this forum do. I do however, take the extra steps, take the extra classes, read the articles and studies and do my research.


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## Handsome Robb (Oct 26, 2011)

shockinainteasy75 said:


> A. I would kill a driver who drove like an idiot with any pt. I do not advocate that kind of transport. However i am completely honest with my pts, they know somethings wrong and by telling them the truth it takes away from the anxiety of "not knowing".
> 
> B. You are correct in that aspirin does not dissolve a clot, however, aspirin is listed as a primary initial step under reperfusion therapy in both ACS and Ischemic stroke. In the future i will be more precise with my words.
> 
> ...



A. I didn't say anything about idiot drivers. I'm all for being honest with my patients, however transporting them with lights and sirens will increase their anxiety far more than simply telling them what is happening and transporting routine. Code 3 transport barely saves any time. In a rural setting it may be warranted but at that point is when I would consider Aeromedical transport (thats another can of worms all together) but not in an urban setting. 

B. Fair enough, we both seem to agree on aspirins roll in reperfusion, its a step, but technically has nothing to do with reperfusion.

C. It may move to a branched artery, yet it may also be caught in the turbulent flow found at bifurcations of blood vessels. We can play the "what if" game all day.

D. I don't feel pity, however I am empathetic towards their problem. Humane isn't technically the correct word, and I'll agree with you on that, however *random point here* does the Humane Society feel pity towards animals? 

Definition of pity taken from dictionary.com : sympathetic or kindly sorrow evoked by the suffering, distress, or misfortune of another, often leading one to give relief or aid or to show mercy.

Humane as defined by dictionary.com: characterized by tenderness, compassion, and sympathy for people and animals, especially for the suffering or distressed.

From these definitions I would personally define analgesics as humane, but thats just me. 

E. I concede, I misread your post.

F. Agreed it is up to the medical director of the service. Yes they do point out the *potential* positive effects of hyperoxygenation, however they prove through scientific studies the ill effects as well. I am aware of how pulse oximeters work regarding saturation of hemoglobin. 




shockinainteasy75 said:


> ill stick with the original miracle drug.



This is where I started questioning your education level. Oxygen is not a miracle drug. Besides in ACS another immediate point that comes to mind is hyperoxygenation in the presence of ICP and it's effects on CPP. I apologize for jumping to conclusions. I'm glad there are providers out there striving to further their knowledge.


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## shockinainteasy75 (Oct 26, 2011)

Though we disagree on points i like this kinda of conversation. Opens up new ideas and allows me to learn new things. As for the "miracle drug", that was a joke pointing to the last few years where everybody got it. I appreciate you bantering with me. If you have any other points to share feel free to PM me, id love to see some more of your opinions.
-Chris


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## systemet (Oct 27, 2011)

shockinainteasy75 said:


> C. When it comes to NTG, i said nothing about clot busting, it vasodialates, and even if the clot moves, we now have the chance of it moving to a more branched vessel, decreasing the area of injury/ischemia.



Your primary benefit from NTG is probably on the demand-side, through preload reduction.  The effect of increased collateral flow is probably minimal.  There's little to no evidence supporting a benefit of NTG in MI, despite several theoretical mechanisms.



> F. No, hyper oxyenation is not a "proven", nor "disproven" fact. Certain agencies support and others refute. That is completely up to the providers and the service area. This can go on and on involving the dispute of pulse oximeters, remembering that pulse ox's determine the % of hemoglobin saturated with something, may not always be oxygen. And even in the studies that support the ill effects of hyperoxygenation, they are quick to point out that the potential positive effects of supplemental oxygen at low concentrations out weigh the potential ill effects of this therapy.



What is a proven fact though, is that the myocardium at rest extracts ~ 80% of transported oxygen.  It's supply-dependent.  When demand goes up, coronary blood flow has to go up.

Not only does increasing the pO2 with high FiO2 have a marginal effect on oxygen transport, high pO2 may cause further coronary constriction and worsen coronary perfusion.

While pulse oximeters may detect carboxyhemoglobin as oxyhemoglobin, giving a false high reading, methemoglobin tends towards a lower reading under most circumstances.  Giving oxygen just because the patient may have been exposed to CO, without having other information supporting this, seems foolish.


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## systemet (Oct 27, 2011)

A few snippets from one review article:

* "In patients with MI, hyperoxia reduces cardiac output
and stroke volume and increases the mean arterial pressure and
systemic vascular resistance.25–31 If the baseline arterial oxygen
saturations are >90%, high concentration oxygen does not
increase oxygen transport, as the reductions in cardiac output
are in excess of the increase in oxygen content.26 The adverse
haemodynamic responses are greatest in patients with MI not
complicated by heart failure or cardiogenic shock."

* "The magnitude of the reduction in coronary blood flow with
hyperoxia may be substantial in patients with coronary artery
disease. This has been illustrated by two studies19 20 which used
the measurement of intracoronary Doppler flow in subjects
with stable coronary artery disease. Breathing 100% oxygen by
face mask for 10–15 min decreased coronary blood flow by 20–
30% in association with a 23–40% increase in coronary
resistance"

* "These effects are
likely to be secondary to an effect on coronary endothelial
function, with the accelerated oxidative degradation of coronary
endothelium-derived nitric oxide by reactive oxygen species"

* "Another potential mechanism is that hyperoxia resulting
from high concentration oxygen therapy may exacerbate
reperfusion injury to the heart owing to the increased
production of oxygen-free radicals"


Wijesinghe M, Perrin K, Ranchord A, Simmonds M, Weatherall M, Beasley R.  Routine use of oxygen in the treatment of myocardial infarction: a systematic review.  Heart (2009) 95:198-202 doi.10.1136/hrt.2008.148742


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## 18G (Oct 27, 2011)

JPINFV said:


> [youtube]http://www.youtube.com/watch?v=xuZl9tRqjoQ[/youtube]



lol.. that was pretty great.


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## STXmedic (Oct 27, 2011)

18G said:


> lol.. that was pretty great.



Sadly I watched the whole thing...


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## usalsfyre (Oct 27, 2011)

18G said:


> lol.. that was pretty great.



The best patient is intubated and sedated on a midaz and fentanyl infusion .


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## silver (Oct 27, 2011)

systemet said:


> * "The magnitude of the reduction in coronary blood flow with
> hyperoxia may be substantial in patients with coronary artery
> disease. This has been illustrated by two studies19 20 which used
> the measurement of intracoronary Doppler flow in subjects
> ...


Intravascular ultrasound (IVUS) is so much fun, however not so much for the patient. Though I am not sure how they determined flow. It measures radius/diameter and you can visualize the plaque. I guess from that you can equate flow...


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## angrynuni (Oct 29, 2011)

Linuss said:


> If you're stumped, you can stare intently at the screen as if trying to read something.  Need more time?  Print off a 12 and stare even more intently at that, then say something that sounds like a rhythm.



laughing from this brought me to tears


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## jjesusfreak01 (Nov 2, 2011)

Linuss said:


> If you're stumped, you can stare intently at the screen as if trying to read something.  Need more time?  Print off a 12 and stare even more intently at that, then say something that sounds like a rhythm.



In my EMT-I class, we can ask for 12-leads in scenarios, however if we then ask what we see, the instructor replies, "looks like a 12-lead".


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