Blood Component Therapy,
Autologous Platelet Concentrate and Fibrin Sealant in
Surgery
Background:
The applications for
autologous platelet concentrate and fibrin sealant are
numerous and are growing continuously. Recent increased
awareness of limited supplies and rising costs of donor
blood products have caused medical practitioners to examine
methods of improving haemostasis in surgery. The use of
advanced blood component therapies clearly demonstrates
improved peri and post operative haemostasis minimising
or eliminating the need for allogeneic blood transfusion.
Platelet Gels (autologous growth factors) have exceptional
qualities in providing enhanced wound healing, tissue
repair and stimulation of bone growth.
Autologous platelet
rich plasma (PRP) for platelet gel (PG) production was
developed in the early 1970's as a by-product of multi-component
pheresis. Techniques and devices have dramatically improved
through the 1990's. At present, various blood cell processors
are available with which platelet pheresis and auto transfusion
can be performed along with specialised point of care
devices, exclusively designed for low volume platelet
gel therapies.
Procedure:
Depending on the type
of surgical procedure and the calculated amount of platelet
concentrate required, a pre-determined amount of whole
blood (50 to 100m1, low volume concentrate, 300 to 450m1,
high volume concentrate) is pre-donated from the patient.
The blood is drawn in the anaesthetic room, after induction,
into a standard blood collection bag containing a citrate-phosphate-dextrose
anticoagulant. The blood is then centrifuged by using
a variable-speed centrifuge blood cell separator to separate
the buffy coat (PRP), suspended in plasma, from the red
blood cell pack and platelet-poor plasma fraction.
The PRP and the platelet
poor plasma (PPP) are the key products for advanced blood
management therapies, the erythrocyte concentrate is reinsfused
into the patient immediately after separation (15 to 20
minutes).
While white cell content
increases 125% with selection for lymphocytes and monocytes,
the inclusion of platelets and white cells appears to
have several
beneficial aspects. White cells confer additional healing
cytokines while some think that it also provides antibacterial
activity.
On activation with
thrombin/calcium to form a coagulum, the platelets interdigitate
forming a fibrin web, developing a gel with adhesiveness
and strength materially greater than the plasma alone.
Besides creating a watertight seal in minutes (haemostatic
component) it also promotes very effective local tissue
growth and/or repair. The influence of thrombin (the most
potent platelet activator) initiates release of platelet
derived growth factors, which are present in the dense
a-granules of the platelets. The thrombin/calcium mix
also causes platelets to immediately release highly active
vasoconstrictors, including beta thromboxane and serotonin.
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