FW: Carboxyhemoglobin Levels

Wed Oct 25 18:45:17 BST 2006

I will speak to George, and see if he could put together a list of the
more salient and cogent articles for those interested.  It may take a
couple of days, but I will do my best to move the educational process
along.

Remember that he is far smarted, and much more well versed in the field
than I  - but I am definitely a convert (there goes the religious end of
this again!!)  ;-) 

May G-d bless you and keep you,
Ron

>>> "Robert Smith" <rfsmithmd at comcast.net> 10/25/2006 1:32 PM >>>
Ron,

I'd love to have those references also. I did a 1 month course with
the
MIEMS HBO guys back in the day. Of course I was all excited about it
then
and was definitely taken aback by the vehement opposition from the
surgical
community back home. Even for stuff like radiation necrosis which at
the
time I'd thought had pretty positive science. But please no flames, I
haven't read the lit in over 20 yrs.

Rob 

-----Original Message-----
From: trauma-list-bounces at trauma.org
[mailto:trauma-list-bounces at trauma.org] 
On Behalf Of Ronald Gross
Sent: Wednesday, October 25, 2006 1:06 PM
To: Trauma &amp; Critical Care mailing list
Cc: George Perdrizet
Subject: RE: FW: Carboxyhemoglobin Levels

Pret,
How unlike you to be so opinionated - sorta like the guy who doesn't
know
how to answer when asked, by his wife's divorce lawyer, "Exactly when
did
you stop beating your wife?"  No facts to base his assertion upon, but
made
it anyway.

I would refer you to an extensive body of literature (most but
definitely
not all of it well researched and written) that will show even those
who
have already made up their minds to the contrary, that there actually
are
disease processes out there that are in need of this particular
treatment.  

Before you impale yourself on the sword of the  "anti-hyperbaric
religious
right stance", I humbly suggest that you come down south a couple
hundred
miles from your perch in Maine to a city called Hartford (still, last
I
checked, on planet Earth) and avail yourself to the knowledge of a
pretty
savvy clinician, educator, scientist and researcher (Dr. George
Perdrizet)
and look at the results of the hyperbaric medicine program that he has
developed and brought along. 
You just might think twice before launching into the sort of thing that
Rob
Smith was referring to the other day - and that I mentioned above - and
that
would be religious condemnation of that which we are not really
familiar
with.

Just my humble opinion.......
Ron

>>> "Bjorn, Pret" <pbjorn at emh.org> 10/25/2006 9:50 AM >>>
You don't read many pages on HBO before you bump into the assertion
that
it's basically a treatment in search of a disease.  But beyond that
debate,
let me observe that its benefits -- anecdotal, academic, hypothetical
or
otherwise -- must be measured in the context of what a pain in the ass
it
is.  

Finding, accessing, and delivering care in a chamber matching the needs
of a
critically ill or injured patient usually generates more risk and
frustration than benefit.  A chamber with real medical functionality
is, for
most of the planet, out of reach.  Little wonder that there's no
reliable
literature when the proper equipment is far more likely to be found on
a sub
base than in a licensed hospital, much less a trauma center.  

JMO

Pret Bjorn
Bangor, ME USA

-----Original Message-----
From: trauma-list-bounces at trauma.org 
[mailto:trauma-list-bounces at trauma.org] On Behalf Of Ian Seppelt
Sent: Tuesday, October 24, 2006 10:54 PM
To: Medic541 at hotmail.com; trauma-list at trauma.org 
Subject: Re: FW: Carboxyhemoglobin Levels

COHb is merely a marker of CO exposure and the absolute level does not
help
a lot without knowing the history (and mechanism) of intoxication and
duration of oxygen therapy before the blood was taken.

It is unfortuantely a medical student myth that CO causes "hypoxic
hypoxia"
by irreversibly binding to Hb. While the irreversible binding bit  is
true,
it is irrelevant. A patient with COHb 50% is likely to die (even
though
there is still 50% oxyHb) while a patient who has lost half a blood
volume
on the road (replaced with Ringers) could well be fine, depending on
what
the injuries are.

A dog experiment from the 1970s involved severe CO exposure (to COHb
60
- 70%) and then exchange transfusions. The intoxicated dogs died
anyway,
even with perfectly good non CO blood from donors, whereas when the
COHb 70%
blood was infused into other volunteer dogs they were fine, and just
behaved
as if they were a bit anaemic (increased HR and CO).

In fact the problem with CO is what the molecule does at the tissue
and
enzymatic level, for example the irreversible lipid peroxidation which
explains all the neurological toxicity from CO.

In terms of therapy there is a large can of worms, polarised by true
believers and non believers. True believers in HBO point to
significant
improvements in things like the long term neurological sequelae of CO
intoxication, but the quality of evidence is at the level of case
series.
There are serious flaws in most of the controlled trials. The strongest
is
Weaver LK, Hopkins RO, Chan KJ, Churchill S, Elliott CG, Clemmer TP,
Orme
JF, Thomas FO, Morris AH. Hyperbaric oxygen for acute carbon monoxide
poisoning. New England Journal of Medicine 2002;347(14):1057-67. 

It is also likely that outcomes vary depending on aetiology. In
Australia
most CO intoxication is either due to attempts at suicide, or due to
enclosed fires (ie house fires, where a lot of other nasties are
inhaled as
well). In colder climes much more of the exposures are industrial or
accidental, and it is likely that outcomes are different in these
different
groups.

The most recent Cochrane review is attached for your interest.

Cheers, Ian

Ian Seppelt FANZCA FJFICM
Senior Staff Specialist
Dept of Intensive Care Medicine
The Nepean Hospital, PO Box 63 Penrith NSW 2751 Clinical Lecturer,
University of Sydney

>>> Medic541 at hotmail.com 24/10/2006 7:42am >>>
To all on this group.  Some advice is needed regarding
carboxyhemoglobin
levels on certain patients.  What levels are permissible to treat only
with
1.0 Fio2?  What levels are treated with a hyperbaric therapy?  Let's
start
from neonates all the way up to the elderly.  If anyone has some advice
or a
website that might point me in the right direction.  That would be
helpful
as well.  I'm trying to find hard numbers, but I cant seem to Google it
for
the life of me.  
  Thanks'
  Anthony M. Caruso
  NREMT-P

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