O2 bad for heart attack patients

[freshwaterdiver]

How long are heart attack victims on oxygen before this becomes an unwanted side effect anyway?

The article appears to suggust that with increased oxygen in the blood, the suggestion is that the body appears to reduce blood flow.
I'm pondering - what effect might this might have when faced with a DCS oxygen admin situation?

[clockworkdog]

Originally Posted by dlegros

Chronic Obstructive Pulmonary Disease.

It is a degenerative condition covering such things as emphysema where there is permanent lung damage.

In some patients with COPD, the physiology that causes you to breathe changes and instead of relying on high pCO2 in the blood, they rely on low pO2, thus administering high flow oxygen can cause respiratory distress and even ventilatory failure.

However, even in COPD hypoxia (low oxygen) kills - we go for high flow oxygen until arterial blood gas analysis gives us more information.

As for contraindications to oxygen - Paraquat poisoning, as high oxygen levels increase the toxicity in the acute phase.

HTH

Paraquat poisoning - nasty! A good example though (don't see many of those )

[clockworkdog]

Originally Posted by freshwaterdiver

How long are heart attack victims on oxygen before this becomes an unwanted side effect anyway?

The article appears to suggust that with increased oxygen in the blood, the suggestion is that the body appears to reduce blood flow.
I'm pondering - what effect might this might have when faced with a DCS oxygen admin situation?

On O2 for long periods of time. Paramedic arrives, gives O2, 12 lead ECG, anticoagulent, enti-emetic & analgaesia. Also followed by thrombolysis assuming authority from A&E after ECG modem transmission. Patient stays on O2 then during transit to hospital and during initial A&E stay. Can be for an hour or so. I would think that the study is suggesting that the O2 is a problem during this initial treatment phase.

As for other question - now that's getting heavy! During a heart attack the heart won't be as effective in ensuring supply of O2 around the body so heart works harder - this can increase the severity of the infarction and ultimately lead to an arythmia that causes output to stop. O2 will help ease the shock and reduce the work the heart has to do. The new study suggests however further complications for the heart.

During a DCS incident O2 will help increase the O2 window and help more rapid off-gassing. I would suggest that the potential small decrease in pulse rate will go nowhere near off-setting the benefits of the massively increased O2 window. This is getting very specialist! Any hyperbaric specialists out there?

Andy

[nigelH]

Having been on the wrong end of this I was quite glad that I was breathing O2 when my wife pointed out "His lips have gone blue". OK. The problem probably was that what I was breathing wasn't getting pumped round but it was still one of those defining moments in my life and left this poor little physicist thinking "O2 is my friend".

Personally I can throughly recommend heart attacks. Most of my family go with the most horrible, long drawn out complications and I'd shoot myself before submitting to the treatment, let alone the illness, that took my poor wife. I know some people manage to drag it out but if that one had got me on cue it would have been over before I realised the gravity of the situation.

[Fee]

I would like to clear up a couple of points.
Clockworkdog's first post: Yes, when people drown their heart stops; however this is due to the massive metabolic insult of hypoxia, possible fluid ingress to the lungs etc, not a primary cardiac event caused by "furring up" of the coronary arteries. The two things are completely different.

As mary pointed out, it is sometimes difficult for anyone, even an experienced doctor with an ECG machine, to tell if this is angina or a heart attack.

Thirdly, while the paper is interesting, it makes no comment on the quality of its sources. Just because the 1950s study was a randomised, double blind study (the "gold standard" of clinical trials) does not make it a good trial, or applicable to todays patients. The study may have inclusion or exclusion criteria we know nothing about, it may have been underpowered, and we know nothing about the statistical significance. Heart attack patients are diagnosed and treated differently these days, often with drugs that produce increased blood flow to the heart, which may offset these effects. The other trials mentioned talk about physiological measurements, but none mention an outcome measure i.e. was there a statistically significant difference in outcoems (e.g patient mortality, development of complications etc).

Lets put it this way, when the next possible heart attack rolls through the door on my take, I would expect him to be on oxygen. If my mum were to have a heart attack, I would want her to have oxygen. There may not be a great deal of evidence for benefit, but there is very little for harm. By the way would anyone be willing to enrol themselves in a randomised trial - if you are having a heart attack, you will be randomised to either oxygen or room air?
PS if the author of the paper can suggest what else we should do if we can demonstrate that the patient is hypoxic apart from turn up the O2, I'd like to hear it.

[Neil McLeod]

Originally Posted by Fee

I would like to clear up a couple of points.
Clockworkdog's first post: Yes, when people drown their heart stops; however this is due to the massive metabolic insult of hypoxia, possible fluid ingress to the lungs etc, not a primary cardiac event caused by "furring up" of the coronary arteries. The two things are completely different.

As mary pointed out, it is sometimes difficult for anyone, even an experienced doctor with an ECG machine, to tell if this is angina or a heart attack.

Thirdly, while the paper is interesting, it makes no comment on the quality of its sources. Just because the 1950s study was a randomised, double blind study (the "gold standard" of clinical trials) does not make it a good trial, or applicable to todays patients. The study may have inclusion or exclusion criteria we know nothing about, it may have been underpowered, and we know nothing about the statistical significance. Heart attack patients are diagnosed and treated differently these days, often with drugs that produce increased blood flow to the heart, which may offset these effects. The other trials mentioned talk about physiological measurements, but none mention an outcome measure i.e. was there a statistically significant difference in outcoems (e.g patient mortality, development of complications etc).

Lets put it this way, when the next possible heart attack rolls through the door on my take, I would expect him to be on oxygen. If my mum were to have a heart attack, I would want her to have oxygen. There may not be a great deal of evidence for benefit, but there is very little for harm. By the way would anyone be willing to enrol themselves in a randomised trial - if you are having a heart attack, you will be randomised to either oxygen or room air?
PS if the author of the paper can suggest what else we should do if we can demonstrate that the patient is hypoxic apart from turn up the O2, I'd like to hear it.

Must agree. With almost no exceptions as listed above): "Oxygen good, clingfilm bad". Even in COPD, with the exception of the true Pickwickian, of which I think I've only meet one in over 25 years, O2 is to be used at as high a rate of delivery as you can get. The slight increase in PCO2 seen with O2 administration to the hypoxic patient can be accounted for by the Haldane shift and not by depression of the respiratory drive.


Neil

[Fee]

"oxygen good"
Somehow, didn't need to check your profile to see you are a gasman!!!