Treating suspected DCI with 100% O2 (is it wrong?)

Deepthought

Hi Guys,

I've always worked on the opinion that the best treatment for suspected DCI is 100% O2 preferably via a demand valve but failing that a non-rebreather bag mask.

I emailed a chap who is selling a 4 lpm / 8 lpm O2 kit in the dive section on ebay (because the flow seemed too low to me - I was taught 15 to 25 lpm)and his response was as follows:-

"you do not treat anyone with dci with 100%oxygen because it can do a lot of damage you should use helem and oxygen because pure o2 makes the vains cotract making it harder for the bubble to flow round the body if used pure 02 the vains cotract which could cause a big problem"

Apart from the inability to spell (Presume he means Helium and veins contract) his opinion seems very wrong.

While a Helium Oxygen mix would have a similar effect in terms of flushing Nitrogen, maintaining O2 saturation has also got to be a high priority.

Given a choice between 100% O2 ; 50% He/O2 ; 79% He / 21% O2

I would be going for the 100% O2 every time.

Though some people say laughter is the best medicine and getting someone to describe their symptoms in a high pitched helium induced donald duck voice could cause much hilarity.

Cheers

Andy

hchoat

If treating suspected DCI with 100% O2 is wrong, then DAN has developed an entirely incorrect protocol (doubtful). I'm not quite sure the ebay seller knows what he is talking about.

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divetheworld

Always 100% unless there is an oxygen induced or related complication. In 99.9% of cases the benefit would outweigh any negative side effects and pure should always be administered.

Brent

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Janos

I know that there is some cutting edge stuff looking at treating bends with Heliox 50/50, but I think that's only for chambers. Someone more knowledgable than me will be along shortly I'm sure.

But 100% O2 it is on the surface.

Janos

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E-man

I remember seeing a study done by the USN that showed that a mix of argon/oxygen flushed nitrogen out of the body faster than pure O2, because the body reduced blood flow because of the high oxygen content of the pure O2....I'll dig it up tonite and post the book that it came from and the results....I'm not saying either method is correct because well I dont know

It does make some sense to me unless the DCI was due to helium..then I dont think adding helium would help.

dteubner

Of course you don't treat DCI with 100% O2 - you treat it with 280%.

First aid for DCI, on the other hand, should include 100% O2 - or as near to it as possible. If the transport to the chamber is going to be very prolonged then there are issues with pulmonary oxygen toxicity which can make things a bit more difficult but that is best worked through at the time with whoever is going to be treating the patient.

If you breathe 100% O2 you will be off gassing from bubbles. If you breathe any inert gas there will be some gas flux from the bubble to the blood and some from the blood to the bubble. Whether or not the bubble will shrink depends on the differences in these fluxes. Theoretically, because of it's lower solubility, He will move into bubbles more slowly than N2 will move out so there might be some benefit for nitrox (air) bends in breathing He. There is some animal evidnece that (air) bubbles in fat shrink faster with He than O2.

That aside, current treatment for DCI involves 100% O2 at 2.8 ATA with the option to go deeper (and therefore necessarily adding an inert gas) if the clinical situation dictates.

I think the quote in the first post shows that the bloke's understanding of decompression physiology is even worse than his spelling.

Dave T

Genesis

What the others have said.

On the surface, first aid for DCI is 100% O2. Why? Because there's no inert gas in there, which maximizes the gradient. That's the point - until you can get the victim to a chamber where they can add crushing the bubbles to maximizing the gradient.

There ARE some instances where pure O2 is dangerous (in someone with an impaired CO2 breathing reflex) but those folks are EXTREMELY unlikely to be diving in the first place - that usually shows up with someone who has severe emphysema and their body has developed an adaptive response where arterial PO2 mediates the breathing reflex instead of blood CO2 content. Those folks have such severe compromise of their pulmonary function in the first place that they are are unlikely to be able to exert themselves at a level necessary to pass even a PADI swim test.....

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E-man

P.S. I re-read the study that was done and the effects were quite the opposite of what i thought.. DOH! It was showing the postive effects of pure O2 which leveled out around 3ATA

Deepthought

Cheers to Dave T and others,

My wording should have been more carefully chosen, to best treat a DCI does of course require a hyperbaric chamber

Please subsequently regard this post as relating to the best "First Aid" for suspected DCI.

It'll be fascinating to read E-Man's Argon study if he gets a chance to post, thanks in advance.

I also suspect we will still be using our (100%) oxygen kits for the foreseeable future (though of course a CCR can be used to deliver 100% at a pinch).

I was just amazed that somebody thought 100% o2 was a bad idea

That said a recent UK tv program showed a diver on a boat with suspected DCI SITTING UP! Fortunately the chaps in the rescue helicopter were on the ball and ordered an appropriate 'Attitude' adjustment .


Here's hoping that no-one ends up with the 8lpm eBay O2 kit thinking it would be a good treatment option - it might be worth a bid for a spare O2 cylinder and case but the bid is currently £57 and a brand new Ally Jumbo D Medical O2 cylinder can be had for about £85 (And in the US its half that !) - can't find the link to the cylinder I'm thinking about but

http://www.micglobal.co.uk/pp/Medica...%20liters.html

@ £84.95 + VAT/carriage

Again, thanks for the comments

Andy

I dont like fundamentalists, fatalists or realists - in fact, any sort of list sounds way too organised

Deepthought

E-Man beat me to the post so ignore my above comments about the Argon study