Too much oxygen?

[Kiwiology]

Care to expand on that? Or do you just enjoy making moronic statements?

Maybe he enjoys pain? Who knows

[systemet]

I bet $1000 more patients have been hurt by lack of EMS oxygenation than too much EMS oxygenation.

That's not what's being discussed here. No one is advocating withholding oxygen therapy from hypoxic patients. What's being debated is whether there's any point in routinely giving supplemental oxygen to normoxic patients with specific medical conditons, e.g. CVA, MI.

The reality is, there's not a lot of evidence in either direction here. But there's a lack of a plausible physiologic mechanism by which supplemental oxygen in normoxic patients could cause benefit. There are a few suggested mechanisms by which hyperoxia could cause injury, but these aren't really supported by epidemological studies, yet. There's just a general absence of research in this area.

It's likely that, in the entire history of EMS, more patients have been harmed by not receiving oxygen, than by receiving too much. Especially as we really don't know how much, if any, damage hyperoxia causes in adult patients. But that's not a logical argument for using oxygen empircally in every MI.

[nypamedic43]

This has been a really great learning experience for me. I didn't post the article to start arguments but the replies and studies have been very educational. I never really thought about it before, but I am now

[Kiwiology]

There are a few suggested mechanisms by which hyperoxia could cause injury, but these aren't really supported by epidemological studies, yet. There's just a general absence of research in this area.

I've been on about this for years and have stated several times in this post the empirical basis for a conclusion that hyperoxia is bad; however that said we cannot base our treatment on the empirical or we'd still still be putting two big bore drips in every trauma patient, infusing litres of crystalliod and blowing up those MAST pants.

You good sir are correct in saying that the evidence base is limited but what evidence exists seems to be pointing away from routine use of supplemental oxygen in the normooxaemic patient. Do we give the normovolaemic patient IV fluid?

http://heart.bmj.com/content/95/3/198.full

http://archinte.ama-assn.org/cgi/content/extract/archinternmed.2011.624v1

http://www.jephc.com/full_article.cfm?content_id=576

http://www.medscape.com/viewarticle/752314

http://content.onlinejacc.org/cgi/reprint/56/13/1013.pdf

It's likely that, in the entire history of EMS, more patients have been harmed by not receiving oxygen, than by receiving too much. Especially as we really don't know how much, if any, damage hyperoxia causes in adult patients. But that's not a logical argument for using oxygen empircally in every MI.

I'm going to disagree and say that the acutely hypoxaemic patient is not hard to spot and will routinely get a high volume of oxygen shoved down their gob by nonrebreather mask.

We should not only consider the patient with stroke or myocardial infarction but patients who are at risk for re perfusion injury i.e. post-ROSC and those patients who receive manual ventilation; there is much confusion that ventilation equals oxygenation (another pet hate of mine that fucks me off no end and makes me want to smash people in the head with the oxygen tank) and universally I think it's been common place to ventilate the snot out of people where flooding their cells with oxygen might not be a good idea; e.g. a narcotic overdose with a hypoxic noggin

This has been a really great learning experience for me. I didn't post the article to start arguments but the replies and studies have been very educational. I never really thought about it before, but I am now

Glad we could be of help

[Richard B the EMT]

There are lies, damned lies, and statistics.

Samuel Clemens, A K A Mark Twain.

[systemet]

I've been on about this for years and have stated several times in this post the empirical basis for a conclusion that hyperoxia is bad; however that said we cannot base our treatment on the empirical or we'd still still be putting two big bore drips in every trauma patient, infusing litres of crystalliod and blowing up those MAST pants.

I'm a little confused by the first sentence, but I think we agree here. There's not a lot of good evidence, so we're mostly relying on expert opinion, with all its inherrent weaknesses.

Regarding MAST and high volume resuscitation, these were practices that changed, at least partly, due to evidence-based medicine. But when we don't have high quality data, we're forced to make a decision anyway. I just think it's important to be aware of the lack of information available in such cases. I think you probably agree with this too, right?

You good sir are correct in saying that the evidence base is limited but what evidence exists seems to be pointing away from routine use of supplemental oxygen in the normooxaemic patient. Do we give the normovolaemic patient IV fluid? http://heart.bmj.com...t/95/3/198.full http://archinte.ama-...nmed.2011.624v1 http://www.jephc.com...?content_id=576 http://www.medscape....warticle/752314 http://content.onlin.../56/13/1013.pdf

I think we agree here.

The only thing I'll add is that physiological arguments are nice, and there's a lack of physiology to suggest that hyperoxia is going to confer benefits.

The trouble with this, though, is we can often make plausible physiological arguments for therapies that don't work. That's why we need more data. This is reflected in some of the sources you've cited, for example:

"We conclude by suggesting that there is insufficient evidence to support the routine use of high-flow oxygen in the treatment of uncomplicated MI. The balance of the limited evidence that exists suggests that the routine use of oxygen in this situation may increase infarct size and possibly increase the risk of mortality, owing to its haemodynamic effects, including a reduction in coronary blood flow. Major international guidelines do not appear to represent the current evidence base and may need revision. There is an urgent requirement for randomised controlled trials of the use of oxygen therapy in MI that are sufficiently powered to enable the risk of mortality to be assessed. "

(From the first source, the Heart article that I also cited earlier).

Everyone's recognising there's a lack of decent data in humans, that we need more, and that animal data is equivocal.

I'm going to disagree and say that the acutely hypoxaemic patient is not hard to spot and will routinely get a high volume of oxygen shoved down their gob by nonrebreather mask.

I think you're unintentionally strawmaning me here. I've never said that it's particularly difficult to identify acute hypoxemia (although pulse oximetry certainly helps), nor that everyone should get a non-rebreather. Just that we don't have decent evidence as to whether hyperoxia is dangerous in humans, and how dangerous it is.

Maybe I was unclear, but if you look back at my previous post, you can see I said "But that's not a logical argument for using oxygen empircally in every MI."

All the best.

[Kiwiology]

I agree with your points

[ERDoc]

There is so much we do in medicine today that we do because it just make sense. It's interesting to see how much changes when you actually do studies. I think a big portion of how you develop your opinion on something when there is insufficient data is based on how you we trained/educated. When I first started EMS in 1992, every chest pain pt got 15L NRB. Why? Well, if they are having an MI, they are not getting enough oxygen to the infarcting tissue. So, if you could dissolve some of that life saving oxygen in the plasma you could increase the amount of oxygen getting to the infarction. This was beat into us so much that even now I get a little freaked out not seeing oxygen on a chest pain but I keep it on the inside (and it's been 13 years since I was in EMS). Old habits die hard I guess. Now, who stole my MAST pants?

[Kiwiology]

This was beat into us so much that even now I get a little freaked out not seeing oxygen on a chest pain but I keep it on the inside (and it's been 13 years since I was in EMS). Old habits die hard I guess. Now, who stole my MAST pants?

I knew you emergentologyists liked pain ... sick freaks ... and I took your MAST pants because they're great for pool parties at Jones Beach

[ERDoc]

Kiwi, I think you would fit in better on Fire Island, probably in Cherry Point.