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the blood products most difficult to maintain without unnecessary transfusion requirements in the operating room, particularly for
wastage. This is not necessarily due to a lack of adequate blood donors, procedures where anticipated blood loss exceeds 1,000ml.
but is rather a consequence of the five-day shelf-life of stored platelets. technique involves the collection of shed blood that is centrifuged and
Unlike other blood products, there are no options for long-term platelet washed of contaminants and debris before re-infusion into the
storage such as freezing and refrigeration due to the inevitable patient. This technique is efficient at reducing allogeneic transfusions
incapacitation of platelet function.
A role of platelet substitutes would in the operative setting.
Although objections have been raised about
be for use at times of short supplies of platelets. Additionally, platelet the use of ICS during surgeries for patients with malignancy, there is
substitutes could be helpful for individuals who develop immunological little evidence to suggest widespread metastasis or worse outcome for
refractoriness to allogeneic platelet products, a common scenario for these patients, particularly if irradiation is used for salvaged
patients who have undergone multiple transfusions.
Despite the success of ICS, there are contraindications to
this collection process, including active treatment with thrombotic or
Attempts at synthesising novel platelet substitutes have revolved around thrombolytic agents, surgical site contamination with urine or bowel
pro-coagulant modification of human proteins. For instance, one set of contents and patients with underlying haemoglobinopathies.
animal studies has shown resolution of haemorrhage in ICS is seemingly safe and has not been correlated with increased post-
thrombocytopenic rabbits infused with fibrinogen-coated albumin operative infection risk, salvaged RBCs have been shown to be
Other basic science approaches have focused on using semi- contaminated with microbes from the surgical environment.
synthetic particles coated with platelet receptors to stop acute bleeding
Another option is the use of infusible platelet membranes. Acute Normovolaemic Haemodilution
These agents – expressing platelet receptors – activate adhesion and In the late 1970s, physicians were seeking to develop alternativee
aggregation pathways and promote clot formation.
While the results of techniques to reduce RBC transfusion intra- and post-operatively.
many of these studies are promising, further research needs to be Acute normovolaemic haemodilution (ANH), based on models of the
performed before substitutes are available as a viable alternative to physiology of blood loss during surgery, involves the collection of an
allogeneic platelet transfusion. autologous whole blood unit immediately prior to initiation of
The volume of whole blood removed is immediately
Pro-coagulant and Antifibrinolytic Medical Therapies replaced with a colloid or crystalloid solution, leaving patients
In addition to providing platelet products for the bleeding patient, many essentially normovolaemic.
Should bleeding occur, the haematocrit
attempts have been made to augment the process of fibrinolysis or of the lost whole blood would be reduced secondary to
induce a pro-thrombotic state to slow haemorrhage. Among the most haemodilution. Additionally, in the face of haemorrhage a fresh,
common agents used to prevent or control bleeding for patients with von autologous whole blood unit containing RBCs, coagulation factors and
Willebrand disease is 1-deamino-8-D-arginine vasopressin (DDAVP), a platelets is available at the bedside.
ANH, although not widely
synthetic form of desmopressin that acts to stimulate the release of von employed, has been shown to reduce allogeneic blood product usage
Willebrand factor from endothelial cells.
DDAVP has also been shown in a multitude of settings, including various cardiac, orthopaedic, oral,
to be useful in the treatment of platelet bleeding associated with maxillofacial and liver surgical procedures.
Patients who qualify
uraemia. In this condition, platelet transfusions are generally futile, as for a trial of ANH include those undergoing procedures where blood
allogeneic and endogenous platelets alike are exposed to a toxic milieu. product infusion is likely, those who possess a pre-operative
Thus, for uraemic bleeding, not only is DDAVP an alternative to haematocrit greater than 12mg/dl and those who lack significant
transfusion, but it also represents a better therapeutic modality.
underlying diseases or infections.
Another set of drugs used to stem platelet-related bleeding are Crystalloid, Colloid and Albumin Volume Replacement
antifibrinolytic agents such as aprotonin, epsilon-aminocaproic acid and In the setting of acute haemorrhage secondary to trauma, blood
These therapies are commonly employed in the setting transfusion may not be an ideal first-line therapy, particularly if volume
of bleeding that is refractory to platelet transfusions.
Additionally, replacement is initially desired.
In fact, because of limited supply and
aprotonin and, to a lesser extent, tranexamic acid have been shown to risk factors, blood products should never be used for volume
reduce the need for allogeneic blood product transfusion in the setting replacement alone.
For the acutely bleeding patient, several
of hepatic, cardiac and orthopaedic surgery.
These therapies do carry alternatives to blood transfusion exist, including crystalloid solutions
a risk of hypersensitivity reactions after repeated exposures.
(e.g. Lactated Ringer’s solution, isotonic saline) and colloid formulations
Additionally, the US Food and Drug Administration (FDA) has recently such as starch solutions or albumin.
Recent meta-analyses have
released details about the potential hazards of aprotonin. This drug has shown that there is no survival advantage in providing colloids or
been associated with an increased risk of mortality, as shown by a large albumin instead of crystalloids; thus, for the patient presenting with
Canadian study in which antifibrinolytic agents were utilised to reduce acute bleeding, standard crystalloid formulations should suffice in
allogeneic blood transfusion during surgery.
As a result of this study replenishing lost volume.
and FDA recommendations, the manufacturer of aprotinin has removed
the drug from the US and Canadian marketplace. For the acutely bleeding individual, the decision to initiate RBC
transfusion should depend on tissue oxygen consumption, underlying
Peri-operative Transfusion Alternatives patient disease status and total blood volume loss rather than ‘target’
haemoglobin and haematocrit.
In some studies, conservative
Intra-operative Cell Salvage transfusion strategies have been shown to lead to better overall patient
Intra-operative cell salvage (ICS) is a tool commonly used to reduce outcome and survival.
Often, a well-designed massive transfusion
34 EUROPEAN HAEMATOLOGY 2007
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