Alternative blood products

[Dr Ross Hofmeyr]

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
=93Semper Paratus=94
> -----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
>=20
> Hi all
>=20
> 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.
>=20
> 1.write short notes on chitosan products as adjuncts to haemorrhage
> control including their mechanism of action (7 marks)
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> 2.discuss the role of bovine haemoglobin as an oxygen bridge where =
blood
> products are not available (8 marks)
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> I have no experience using either of these products
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> kind regards
> Sa'ad
>=20
>=20
> Dr Sa'ad Lahri
> Emergency Medicine Registrar
> UCT/US
> Cape Town
> South Africa
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>=20
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