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Fri Mar 21 16:02:54 GMT 2008

Dr Lahri-

A quick once over on the Chitosan dressings:

1.  Originally produced in the US by HemCon Technologies as a cheap / safe
alternative to the fibrin dressing.  The chitosan is a protein derived from
shrimp shells.  No, there's NO danger of anaphylaxis as is commonly asked. 

2. These products were designed for high-pressure arterial bleeding from an
"incompressible" location (meaning that it WON'T accept a tourniquet).
Usually this means an "edge" of body armor ballistic injury--axillary or
inguinal bleed.  

3.  (2) products primarily fielded by US and allied forces for combat
casualties: HemCon Bandage and Chitoflex.  Each has its respective
advantages and disadvantages.  The bandage has a non-stick colored side that
was designed to keep the dressing from adhering to your gloves and thus
being dislodged from where it was placed.  Chitoflex is "active" on both
sides so it can be "packed" into a wound track.

4.  The best way to think of these dressings is to consider them "tire
patches"--they work by adhering to (and thus hopefully "patching") the
damaged vessels.  The chitosan is activated by the blood, attracting the
platelets to the dressing via electrostatic charge.  Unfortunately, getting
them wet with anything (including water, saline or the blood on your gloves)
will cause them to become sticky and adhere to whatever is nearby (including
your gloves).  They are best applied to an identifiable source of
hemorrhage--just like a tire patch.

5.  Controlling the hemorrhage with direct pressure before AND AFTER
placement of the dressing is the key to success.  ANY type of hemostatic
agent will not work if it is "washed away" by the high pressure, high volume
of a real arterial bleed.  Remember--get control of the hemorrhage with
pressure FIRST, place the dressing and then IMMEDIATELY get lots of kerlix
in behind the dressing.  Then, most importantly, get the direct pressure
BACK ON the injury.  You will need to hold it for a minimum of 5 minutes.
That gives the dressing the opportunity to adhere into place and create the
seal.  The amount of pressure is substantial--remember you have to overcome
the arterial pressure. 

6.  The biggest differential in successful placement of these bandages is
training.  Live tissue training is obviously the best option as it gives you
immediate feedback on your technique.

Hope this helps-

Chris Pipes
Director, Special Projects
Deployment Medicine       

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Today's Topics:

   1. Alternative blood products (Sa'ad Lahri)
   2. Alternative blood products (Sa'ad Lahri)
   3. RE: Alternative blood products (Dr Ross Hofmeyr)

----------------------------------------------------------------------

Message: 1
Date: Fri, 21 Mar 2008 09:19:17 +0200 (SAST)
From: "Sa'ad Lahri" <slahri at webmail.co.za>
Subject: Alternative blood products
To: trauma-list at trauma.org
Message-ID:
	<55933.196.207.40.213.1206083957.squirrel at mail.webmail.co.za>
Content-Type: text/plain;charset=iso-8859-1

Hi all

Got asked the following two questions in our Emergency Medicine basic
sciences exam. Could you help with either resources or a short explanation
and your current experience.

1.write short notes on chitosan products as adjuncts to haemorrhage
control including their mechanism of action (7 marks)

2.discuss the role of bovine haemoglobin as an oxygen bridge where blood
products are not available (8 marks)

I have no experience using either of these products

kind regards
Sa'ad

Dr Sa'ad Lahri
Emergency Medicine Registrar
UCT/US
Cape Town
South Africa

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Message: 2
Date: Fri, 21 Mar 2008 09:19:17 +0200 (SAST)
From: "Sa'ad Lahri" <slahri at webmail.co.za>
Subject: Alternative blood products
To: trauma-list at trauma.org
Message-ID:
	<56041.196.207.40.213.1206083957.squirrel at mail.webmail.co.za>
Content-Type: text/plain;charset=iso-8859-1

Hi all

Got asked the following two questions in our Emergency Medicine basic
sciences exam. Could you help with either resources or a short explanation
and your current experience.

1.write short notes on chitosan products as adjuncts to haemorrhage
control including their mechanism of action (7 marks)

2.discuss the role of bovine haemoglobin as an oxygen bridge where blood
products are not available (8 marks)

I have no experience using either of these products

kind regards
Sa'ad

Dr Sa'ad Lahri
Emergency Medicine Registrar
UCT/US
Cape Town
South Africa

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South Africas premier free email service - www.webmail.co.za 
------------------------------------------------------------------
For super low premiums, click here http://www.webmail.co.za/dd.pwm

------------------------------

Message: 3
Date: Fri, 21 Mar 2008 11:31:07 -0000
From: "Dr Ross Hofmeyr" <wildmedic at gmail.com>
Subject: RE: Alternative blood products
To: "'Trauma &amp; Critical Care mailing list'"
	<trauma-list at trauma.org>
Cc: 'Sherry Bremner' <sherry.bremner at gmail.com>
Message-ID: <7299B2EDB9E14D12A4A513619733AF95 at WildMedicPavillion>
Content-Type: text/plain;	charset="windows-1250"

Hello Sa'ad my old friend ;)

I gather by your mail that you attacked the primaries - well done!

The real experts on the chitsoan products are the military crowd, with
battlefield dressings and haemostatics being the predominant use.  I haven't
seen it in SA, or heard of civilian use, although I am willing to be
corrected.  (The only haemostatic I've seen in SA is TraumaDex, which uses
tranexamic acid).  Chitosan is a linear polysaccharide derived from the
exoskeleton of crustaceans (esp. shrimp) that contributes to very rapid
clotting of blood via an ionic reaction between the positively-charged
chitosan granules and negatively charged RBC's.

I'm afraid I don't have any archived articles, but there was porcine
research in J. Trauma in 2003 that showed a dramatic reduction in blood loss
using a chitosan impregnated bandage compared to gauze(Pusateri, A. E., S.
J. McCarthy, K. W. Gregory, R. A. Harris, L. Cardenas, A. T. McManus & C. W.
Goodwin Jr. (2003). Effect of a chitosan-based hemostatic dressing on blood
loss and survival in a model of severe venous hemorrhage and hepatic injury
in swine. Journal of Trauma 4 (1): 177-182) - perhaps some-one on the list
can cough it up.

Bovine haemoglobin is the substrate used in the haemoglobin based oxygen
carriers (HBOC's) - the one you may have heard of in SA is Hemopure.  The
principle of an HBOC is precisely the oxygen bridge you mention - in acute
anaemia or traumatic blood loss where blood is not available, one can
administer an HBOC which raises the plasma haemoglobin (it's an acellular
solution) to the point where O2 carrying capacity is life-sustaining.  The
products have a limited half-life, but can be administered until blood
products become available, or the acute crisis has passed.  There are some
other benefits that are being investigated - the fact that the Hb is in the
plasma rather than cells means that it can theoretically pass through
smaller or partially occluded vessels, thus preserving ischaemic tissue that
would otherwise have infacted.  There is research being done in CT surgery,
and people are looking at it for management of certain types of wounds,
including frostbite.  Another advantage (disclaimer: depending on your
school of thought) is that the HBOC's are a hypertonic solution, allowing
hypertonic, small-volume resus in haemorrhaging patients.  Other upsides
include small physical volume, 3 year shelf-life, and no special storage
requirements.  The downsides?  Well, it's not blood - it does nothing for
clotting.  Too rapid administration can result in a spike in BP.  There have
been reports of renal failure (seems to be predominantly with the older
HBOC's).  Costly.  (Is that worth 8 marks?)

I have some articles that I gathered while I was pushing for a supply of
HBOC here in Antarctica and aboard the ship that I can forward should you
wish.

Will be holding thumbs for you when the results are out!

Regards,
Ross.

Dr Ross Hofmeyr
Expedition Leader  & Doctor
South African National Antarctic Expedition
ross.hofmeyr at sanane.sanap.ac.za
wildmedic at gmail.com
ross at wildmedix.com
www.wildmedix.com
Tel: +2721 405 9428
Skype:  wildmedic
Semper Paratus
> -----Original Message-----
> From: trauma-list-bounces at trauma.org [mailto:trauma-list-
> bounces at trauma.org] On Behalf Of Sa'ad Lahri
> Sent: 21 March 2008 07:19 AM
> To: trauma-list at trauma.org
> Subject: Alternative blood products
> 
> Hi all
> 
> Got asked the following two questions in our Emergency Medicine basic
> sciences exam. Could you help with either resources or a short explanation
> and your current experience.
> 
> 1.write short notes on chitosan products as adjuncts to haemorrhage
> control including their mechanism of action (7 marks)
> 
> 2.discuss the role of bovine haemoglobin as an oxygen bridge where blood
> products are not available (8 marks)
> 
> I have no experience using either of these products
> 
> kind regards
> Sa'ad
> 
> 
> Dr Sa'ad Lahri
> Emergency Medicine Registrar
> UCT/US
> Cape Town
> South Africa
> 
> 
> 
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> South Africas premier free email service - www.webmail.co.za
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