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Date: Thu, 25 Nov 1999 18:53:58 -0800
To: techdiver@aquanaut.com
From: David Reinhard <reinhard@oc*.co*.au*>
Subject: Re: [Fwd: Re: Positive Pressure Oxygen]
>> These people are starting to piss me off ...
>> 
>> I agree 100% on the use of the reg for resuscitation ...
>> Anybody who can't see the advantages ...

Only if you choose to ignore the disadvantages.

>> especially if you have a high 02 mix ????????
>> 
>> What is this nonsense they are spouting about compleatly sealing the reg
>> exhaust?
>> With the nose sealed and a good mouth seal ...

The gas will take the path of least resistance - out the exhaust ports.

>> An unconscious lung will inflate if the airway is open ...
>> Sealing the exhaust ports would be dangerous.

Yes. If you don't manage to rupture the lungs you may well inflate the
stomach.

>> I know you can inhibit flow out the exhaust with your fingers for obvious
>> reasons ...
>> But compleatly sealing it would be dangerous because of the positive
>> pressures you could generate.
>> My LSP surface rescitator unit (pos Pressure)has an exhaust system in the
>> resuscitator head that works just like a reg exhaust ...
>> What's the difference?

The difference is clear and obvious. The pressure relief valve on a
positive pressure resuscitator is set at around 50-70cm H2O. This is
designed to prevent overpressuring the lungs but still provide enough
pressure to overcome the resistance of the airways and chest compliance. If
the pressure is significantly less than this you will not inflate the
lungs. If the pressure is greater than this then you will damage lung
tissue. A reg has no way of ensuring that you deliver the appropriate
pressure. Exhaust ports are designed to provide absolute minimal resistance
(low exhalation effort is just as important as low inhalation effort in a
good reg). It is therefore unlikely that you will achieve adequate pressure
to overcome airways resistance...it is just too easy for the gas to escape
through the exhaust ports. If you have a very high flow rate when purging
then maybe (just maybe) some of the gas will find its way into the lungs.
But you will have no way of regulating this or knowing if the amout that
went in (if any at all) is adequate or too great.

>> 
>> Thought I'd  pass these references along ...
>> I'm sure your alredy aware of a lot of it ...
>> I haven't had a chance to look at any of them yet myself ...
 
How very clever! You typed a key word (probably Resuscitators or something
similar) into Medline and hit "search". Wow...I am impressed. It is such a
pity that none of the articles appear to have anything to do with the topic
in question (ie scuba regs for resus) You may as well have typed in
"wanking machine" or "butt licking"...just as much use and probably a lot
more fun to read.

(Actually I am being a bit flipant. There are a number of articles here
that would probably be of interest to me in my profession...except I
already have about 30 articles on various topics that are awaiting reading
when ever I manage to get the time. However in terms of this specific
debate I do not see any articles that will answer the question being
asked...therefore it is a waste of time and bandwidth since they are
irrelevant to the debate.) 

>> This one caught my eye ...
>> Corley M, Ledwidge MK, Glass C, Grap MJ.
>> The myth of 100% oxygen delivery through manual resuscitation bags.
>> J Emerg Nurs. 1993;19:45-9.
>> 

This one caught MY eye...

 Hartstein AI, Rashad AL, Liebler JM, et al. Multiple intensive care unit
 outbreak of Acinetobacter calcoaceticus subspecies anitratus respiratory
 infection and colonization associated with contaminated, reusable ventilator
 circuits and resuscitation bags. Am J Med. 1988;85:624-31.


Obviously this is the definitive word on using regs for resus!! You can
tell just by reading the title! This article will be packed with
information every diver come rescuer must know before using a reg to purge
someone!!

So where do we stand...so far not one authoritative comment or article in
support of regs for resus. I am waiting...but losing patience (but at least
I am not losing my 'patients'!).

David



>> All the Best ...
>> 
>> Marty H    Canada
>> 
>> P.S. Beginning to understand why you call these people strokes
>>      Feel free to distribute this message if I'm not out to lunch on this
>> ...
>> 

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