# Oxygen, anyone?



## Smash (Mar 22, 2011)

Juuuuuust in case anyone was still laboring under the misapprehension that O2 is some sort of benign panacea:
Effects of oxygen inhalation on cardiac output, coronary blood flow and oxygen delivery in healthy individuals, assessed with MRI. European Journal of Emergency Medicine 2011, 18:25–30

Very small study and done in healthy volunteers, so we need to take care, but the long and the short of this one is that O2 decreased left ventricular perfusion, decreased cardiac output and thus decreased systemic and cardiac oxygenation.  Just add it to the pile!

When I have my STEMI, unless I am shocked or actually hypoxic, I will take that O2 tubing and wrap around your neck very tightly if you try to give me O2.


----------



## DrParasite (Mar 22, 2011)

very interesting.....

http://journals.lww.com/euro-emerge...f_oxygen_inhalation_on_cardiac_output,.6.aspx


----------



## 18G (Mar 22, 2011)

Interesting indeed. It continues to validate what has been known since the late 1950s.


----------



## lightsandsirens5 (Mar 22, 2011)

What I would like to know i just how long it is going to take the average MPD to actually do something progressive and attempt the un-training of all us monkeys.

Unfortunately I am like one of the only ones at my service that thinks like this. The rest make all the usual claims, "Oxygen can't hurt you" "Go big or go home, right?" "Oxygen is good for you, so more is better." But they (of course) can't back it up. I always bring all these articles and research reports in for people to read and I am treated like some kind of heretic. Thank God I just work for the county and not the Roman Catholic Church of Centuries ago, I'd have been burned at the stake by now. I ride a fine line between doing what research has shown is good for my pt and blatantly breaching protocol. (Which idiotically states "apply high concentration/high flow oxygen" on every single page.) I use more NCs than the rest of the crew put together and I also bring in more people without oxygen (What? Stone him to death!) than anyone else. I am not withholding it if they need it, but does a pt with kidney stones and a room air sat of 99% really need any supplemental 02?


----------



## 18G (Mar 22, 2011)

Its made its way to PA protocols already. No more blanket treatment with high-flow O2.


----------



## lightsandsirens5 (Mar 22, 2011)

18G said:


> Its made its way to PA protocols already. No more blanket treatment with high-flow O2.



Are those available online?


----------



## 18G (Mar 22, 2011)

Yes, they are online... All changes and revisions are highlighted. 

Link: http://www.emsi.org/Files/Admin/Statewide ALS Protocols - 2011.pdf


----------



## SeeNoMore (Mar 22, 2011)

Screw that, every pt I touch is getting high flow o2 with a NRB and a stay on a backboard via rapid takedown. 

People need to understand that we are not doctors, we work on the streets and we intubate upside down in ditches in the middle of hail storms. 

This is the streets, no time for egg head studies. h34r:

No this is really intersting, thanks for posting. I need to share with everyone in EMS I know who just refuese to believe 02 is not the best thing ever for everyone in as large ammounts as you can manage.


----------



## Anjel (Mar 22, 2011)

SeeNoMore said:


> Screw that, every pt I touch is getting high flow o2 with a NRB and a stay on a backboard via rapid takedown.



hahaha amazing


----------



## usafmedic45 (Mar 22, 2011)

Anjel1030 said:


> hahaha amazing



But so accurate with regards to how some people think.


----------



## bigbaldguy (Mar 22, 2011)

On a related note the airline I work for just changed our onboard protocols regarding O2. We no longer administer O2 unless told to do so by ground medical personnel via radio or a qualified medical provider onboard. Previously it was SOP to put all ill passengers on O2. All O2 on the aircraft however is low flow however (4 liters max).


----------



## shfd739 (Mar 23, 2011)

I read this then got sent to a breathing difficulty. First responder paramedic (that I know cuz they work for us) has the patient on NRB @15 lpm and is quite proud he is now at 100% sats. Room air initially was 96% with no distress. Why did they use a NRB? Well cause it's a breathing difficulty call. 

I think my eye roll and sarcastic response got the point across. Well that and taking it off of the patient in front of everybody.


----------



## MrBrown (Mar 23, 2011)

Oxygen is not clinically beneficial in all patients and should not be randomly administered.

Use the simpliest device and lowest flow rate to achieve a SPO2 of >95% if the patient appears hypoxic or hypoxaemic. 

Or so Brown thinks


----------



## shfd739 (Mar 23, 2011)

MrBrown said:


> Oxygen is not clinically beneficial in all patients and should not be randomly administered.
> 
> Use the simpliest device and lowest flow rate to achieve a SPO2 of >95% if the patient appears hypoxic or hypoxaemic.
> 
> Or so Brown thinks



My thoughts as well. My soon to start paramedic school partner looked at me funny till I explained this all to him. Lightbulb. Now he understands as well and sees I wasn't trying to be a jerk. Well this time at least.


----------



## Bieber (Mar 23, 2011)

My protocols state that SpO2 will be maintained at >95% at all times and that O2 of at least 2 LPM via NC is mandatory for chest pains.  For all non-chest pain patients, if my patient is maintaining sats above 95% without oxygen with no signs of respiratory distress, then oxygen isn't indicated as far as I'm concerned.  And with chest pains, I err on the lowest necessary dose of oxygen to maintain SpO2 and titrate up as necessary.  Just like any drug, it has to be indicated and/or approved/required by protocol for my to use it, as far as I'm concerned.


----------



## CIRUS454 (Mar 24, 2011)

I kinda learned the same thing in an Advanced Cornary Systems class back in 2004


----------



## CIRUS454 (Mar 24, 2011)

Bieber said:


> My protocols state that SpO2 will be maintained at >95% at all times and that O2 of at least 2 LPM via NC is mandatory for chest pains.  For all non-chest pain patients, if my patient is maintaining sats above 95% without oxygen with no signs of respiratory distress, then oxygen isn't indicated as far as I'm concerned.  And with chest pains, I err on the lowest necessary dose of oxygen to maintain SpO2 and titrate up as necessary.  Just like any drug, it has to be indicated and/or approved/required by protocol for my to use it, as far as I'm concerned.



I completely agree with what you typed. I practice the same thing!


----------



## beandip4all (Mar 25, 2011)

SeeNoMore said:


> Screw that, every pt I touch is getting high flow o2 with a NRB and a stay on a backboard via rapid takedown.
> 
> People need to understand that we are not doctors, we work on the streets and we intubate upside down in ditches in the middle of hail storms.
> 
> This is the streets, no time for egg head studies. h34r:



L-O-to the- L!!


----------



## systemet (Mar 26, 2011)

I took a little bit of time to read the article cited.  It's interesting, and thought-provoking.

However it remains a small study (n = 16) of healthy volunteers.  Their primary finding is that although patients receiving supplemental O2 have a greater arterial oxygen content, they exhibit slower heart rates, resulting in a lower cardiac output, and lower coronary and systemic oxygen delivery.

They speculate, but don't show, that this reduction in O2 delivery results in a decrease in oxygen extraction.  They report no clinical symptoms in their healthy volunteers, as one would expect.  They suggest that reductions in coronary oxygen delivery might be dangerous for "healthy patients" with baseline coronary artery disease.

I absolutely agree that all therapies should be administered in a responsible manner, and should be directed by the patient's clinical presentation.  But I want to point out that this study does not show that oxygen administration is actually dangerous for anyone.


----------



## Chief Complaint (Mar 27, 2011)

Very insightful thread guys and gals.  Good info in here.

I cant speak for every medic program but all ive heard over the last few semesters is that "everyone gets O2".  

Ill be raising my hand a few times during our next lecture.


----------



## Melbourne MICA (Mar 27, 2011)

*Here  - take a whiff of this*

The good gas or not so good  - that is the question. And a question it will remain  (especially in EMS practice) until a substantive body of evidence indicates changes are needed for better clinical outcomes. Small studies in healthy patients are interesting at best but won't cut the mustard with the medical types, conservative lot that they are.

They just might need a little more convincing.

Mind you there is also a trap here for we ambo types that has been revisited more than once in the past and caused more problems than it has solved.

So and so said.....and he had this amazing study which showed such and such.
We need to put all our research together systematically as part of a process not part of conversation. (These remarks aren't intended for you SMASH by the way).

The easy step is introducing topics of conversation and presuming you have a point. The hard bit is proving it conclusively and seeing change result.

Just my thoughts.

MM


----------



## Hal9000 (May 12, 2011)

Small-ish thread necro.  The systems here have ALS providers which are uniformly of the belief that all patients, period, must have oxygen. Sat 99% on RA with complaint of cut on foot sans any other illness, injury, or clinical concern? Gets at least nasal cannula, min. of 4 LPM.

I know this, as the fire medic had a fit and I questioned my boss, who upheld that all our patients must be given oxygen of at least 4 LPM. Of course, they also mandate at least a saline lock on all patients, per the hospital's "request."  And transport all codes with L&S.  And don't count scene time if it's in the back of an ambulance. And it really gets worse. 

Luckily, I'll be (back) out of the business for good soon.   Quite tired of silly medical decisions being made by people who have no collegiate medical history whatsoever.


----------



## mycrofft (May 12, 2011)

*Treatment without benefit is a potential tort and an unnecessary expense.*

Ths study is an anecdote. Maybe we see the body "decompensating" in a healthy subject because it's receptors have sensed that  O2 is up, so a lower degree of cardiopulmonary activity is adequate...in otherwords, it is compensating for a heightened O2 level.
*Maybe*.

If that occurs to an otherwise compromised pt, then it is bad, but if those receptors are still working properly, the pt should not exhibit the same sort of response as the healthy ones.

Folks, "Thuh Meeedia" doesn't use even junior high school science to decide which "studies" or "experts" to expose to "Thuh Peepul" for their edification. We need to be "critical consumers of 'fact' ", as my statistics prof used to teach us to be.


----------



## the_negro_puppy (May 12, 2011)

Hal9000 said:


> Small-ish thread necro.  The systems here have ALS providers which are uniformly of the belief that all patients, period, must have oxygen. Sat 99% on RA with complaint of cut on foot sans any other illness, injury, or clinical concern? Gets at least nasal cannula, min. of 4 LPM.
> 
> I know this, as the fire medic had a fit and I questioned my boss, who upheld that all our patients must be given oxygen of at least 4 LPM. Of course, they also mandate at least a saline lock on all patients, per the hospital's "request."  And transport all codes with L&S.  And don't count scene time if it's in the back of an ambulance. And it really gets worse.
> 
> Luckily, I'll be (back) out of the business for good soon.   Quite tired of silly medical decisions being made by people who have no collegiate medical history whatsoever.



Lol mandatory oxygen and IVs for all patients, is archaeic. wasteful and probably even detrimental. What if the pt with the cut foor gets phlebitis?


----------



## fma08 (May 12, 2011)

mycrofft said:


> Ths study is an anecdote. Maybe we see the body "decompensating" in a healthy subject because it's receptors have sensed that  O2 is up, so a lower degree of cardiopulmonary activity is adequate...in otherwords, it is compensating for a heightened O2 level.
> *Maybe*.
> 
> If that occurs to an otherwise compromised pt, then it is bad, but if those receptors are still working properly, the pt should not exhibit the same sort of response as the healthy ones.



So happy to see someone else had this idea. My first thought when reading the the short version (as I haven't looked at the article yet, but I'll get there) was "well duh". It had seemed to me that with greater O2 availability, the heart wouldn't have to work as hard. Would like to know if it was actual coronary tissue perfusion (oxygen exchange) that was reduced or was it just coronary blood flow that was reduced? Same for systemic circulation.


----------



## systemet (May 15, 2011)

The myocardium extracts about 75% of delivered oxygen at rest.  So it's essentially supply-dependent - it's already using almost all of the delivered oxygen. [This is a much greater value than in most other organs.]

If we reduce coronary oxygen delivery, we're also going to be limiting the total amount of oxygen extracted by the myocardium.  High pO2 results in coronary and cerebral vasoconstriction, and vasodilation in the other peripheral vascular beds.

So if you cause a decrease in coronary blood flow, the oxygen extraction probably isn't going to be able tobe adjusted to compensate. 

The trouble with this reasoning, is that while physiological mechanisms are appealing --- "i_f we give oxygen, we cause coronary vasoconstriction, limit coronary blood flow and reduce oxygen delivery_ which results in cardiac ischemia, dysfunction and poor outcomes in conditions X, Y and Z"  is that so far we've only demonstrated the first half to be true.

I love physiology, but it's possible to postulate plausible physiologic mechanisms for many things, including a beneficial effect for high dose epinephrine in cardiac arrest, or routine hyperventilation in closed head injury.  We have to do outcomes-based trials to demonstrate a treatment effect.


----------



## systemet (May 15, 2011)

Brown posted an awesome link which covers a lot of physiology and gives some clinical recommendations in one of the other 500 current threads about the use of oxygen, here: http://www.brit-thoracic.org.uk/clin...-patients.aspx

The thread is over here:

http://emtlife.com/showthread.php?t=23702&page=4


----------



## usafmedic45 (May 15, 2011)

> The myocardium extracts about 75% of delivered oxygen at rest. So it's essentially supply-dependent - it's already using almost all of the delivered oxygen. [This is a much greater value than in most other organs.]



Wanna try again with that figure or at least give a source for it so I can go smack whomever feed you this crap? You got the last sentence (in brackets) correct, but your figures are massively off.  If you were to actually have a functioning organ like that in the absence of exercise or disease, you'd not be able to stress the organ very much at all.  Not to mention that it exceeds the theoretical maximum oxygen extraction capability severalfold. 

BTW, most organs (other than the brain and heart) run around 2-6% extraction on a % volume basis.  Oddly enough, the intestines are one of the organs at the higher end of this.


----------



## systemet (May 15, 2011)

Sure:

Tune JD, Gorman MW, Feigl EO.  Matching coronary blood flow to myocardial oxygen consumption.  J Appl Physiol 2004 97:404-415  online .pdf here:  http://jap.physiology.org/content/97/1/404.full.pdf+html

If you're looking to slap someone, it appears that you can find Feigl here: http://depts.washington.edu/pbiopage/people_fac_page.php?fac_ID=11

I've never met the man, but he's got the look like he's got a trick or two up his sleeve.  I bet a good slap would be met with some wirey old man strength, and some sort of subtle and cunning plan.


----------



## systemet (May 15, 2011)

The issue here, is that I'm talking the percentage of delivered oxygen, i.e. %DO2, and you're talking the absolute volume of oxygen extracted (i.e. CaO2- CvO2).

So, if you're trying to say that there's no way I can extract 75 ml of oxygen from 100 ml of blood, I'd agree.  This would require fully-saturated blood, and a hemoglobin of something ungodly, like 50 g/dl.  

However, if you're suggesting that the heart is incapable of extracting around 15 ml of oxygen from every 100ml of oxygenated blood that passes through it at rest, i.e. ~ 75% of delivered oxygen, or 75% DO2, then we're in disagreement.

I've seen your previous posts, and I think you're a pretty intelligent guy, so I'm going to suggest that we're actually in agreement here.


----------



## usafmedic45 (May 15, 2011)

*facepalm*  I really need to stop reading the forums after having a few beers.  You're right.  I misunderstood what you said and thought you were talking about % volume and not % delivered. 

BTW, one of the authors is going to get a good laugh out of this.  I've talked to him before.


----------



## systemet (May 15, 2011)

Totally cool.  Beer and the internet is fun, but potentially problematic


----------



## Too Old To Work (May 17, 2011)

As far back as 2000, the AHA started talking about reducing oxygen delivery to stroke patients. The reason is that higher O2 levels cause hypocapnia which in turn causes vasoconstriction which reduces blood flow to the brain. That in it's turn cause the stroke to expand across the penumbra. Which of course is bad for the patient. There is also an Australian study which shows greater morbidity for patients given Albuterol with O2 as opposes to Albuterol with Normoxic air. The article referenced here in "Chest" is very interesting. 

Finally, there are studies of neonatal resuscitation that show babies resuscitated on room air do better than those resuscitated on high flow O2. 

Maybe it's time that EMS discarded the "Chicken Soup" school of medicine.


----------

