Red Cell Transfusion Flashcards
What are our red cell products?
Whole blood
Red Cells Leucocyte Depleted
Partially packed
Washed/Frozen and thawed rbcs
Paedipacks
Talk about whole blood as a product
Rarely used for allogeneic transfusion, despite supplying most deficits
In America it is used in emergencies, especially in the millitary as it contains factors as well etc
Talk about red cells leucocye depleted as a product
The product of choice
Used to increase oxygen carrying capacity without the blood volume expansion of whole blood
What is the expected improvement after a red cell transfusion?
In a typical adult, one unit of red cells is expected to raise the Hb by approximately 1g/dl, or the haematocrit by 3% -> if no bleeding o haemolysis
When might washed/frozen and thawed rbcs be used?
For IgA deficiency -> as patients ill have an anaphyllactic affect to IgA hence need for washed cells
What are the indications for transfion?
Main indication is to increase the oxygen carrying capacity so as to improve tissue oxygenation
It is rarely indicated for a Hb>9g/dl and almot always indicated for a Hb<6g/dl
Other considerations are risk of further blood loss, age of patient, evidence of cardiovascular disease, if patient has decreased oxygen demand, e.g. bed rest etc
Will we always transfuse a Hb of 6?
No if patient has stopped bleeding and the patient has stabilised clinicians will leave it at 6 and not transfuse - they will let it go up on its own once stabilised
However age is an important factor here, a Hb of 6 in an old woman is much more serious than in a young person
Who controls the indications for transfusion
NATA
Network for Advancement of Transfusion Alternatives
What does NATA do?
It reduces transfusion in different cohorts of patients
They found that people can survive on much lower Hb - led to us lowering our cut off for transfusion
They also looked at a lot of studies on cell salvage -> this was funded by Jehovis witnesses
Talk about patient blood management of red cells
One unit transfused at a time as needed (used to be standard practice to give 2)
Not to use a formulaic ordering
Check haemoglobin/Hct between transfusions where possible
Checking PT and APTT, TEG/ROTEM -> if fine then no need for plasma transfusion or clotting factors etc
Regularly update MSBOS
Use alternatives such as cell salvage where approprite
Regular education so staff are aware of the guidelines for use of blood products
Clear protocols for different situations
Use of fibrinolysis inhibitors such as transexamic acid
How can you reduce the need for transfusion prior to surgery?
A lot of people tend to come into hospital already anaemia -> these often need a Hb after surgery -> hence can be treated with iron prior to surgery or opt for keyhole surgery instead
How often is MSBOS determined, why is it so important?
Its agreed upon every year
It tells the clinical staff how many units they should order for each operation
This is the main reason why weve been able to get by with such few donations
What is transexamic acid, how important is it?
Its a fibrinolysis inhibitor
It supports fibrin
It has reduced post maternal haemorrhage deaths by 30%
What are the components of anticoagulants?
Citrate
Sodium biphosphate
Dextrose
Adenine
How does citrate work as a preservative?
It prevents coagulation by chelating calcium
How does sodium biphsophate work as an anticoagulant?
It prevents an excessive drop in pH
How does dextrose work as an anticoagulant?
It supports ATP generation by the glycolytic pathway
How does adenine work as an anticoagulant?
It acts as a substrate for red cell ATP synthesis
What % of red cells must survive post transfusion?
70% viability is the key -> 70% must survive after transfusion, 24 hours post expiry limit
How does mannitol work as a preservative?
Its an osmotic diuretic that acts as a membrane stabiliser
What is the shelf life of CPDA blood?
35 days in Ireland
But 42 days in America
Where do red cells derive most of its energy from?
Energy from the breakdown of glucose to lactate or pyruvate via a sequence of reactions known as the Embden Meyerhof pathway
ATP and 2,3-DPG are the two key compounds produced by this pathway - these are what determine red cell expiry dates and viability
Talk about red cell metabolism in your own words
Anaerobic metabolism
Lactate acid is produced which brings about a pH drop
The more the pH drops the less the red cell can deliver oxygen
2,3-DPG is responsible for pushing oxygen out of the red cell and into tissues
=> the lower the 2,3DPG the less a red cell is able to delliver oxygen to tissue
Talk about the history in the developments in blood storage
In 1914 Payton Rous in NY pioneered combining citrate and glucose to yield a shelf life of 9 days
In 1937 the 1st blood bank in Cook County Hospital in US late
In 1940s Acid Citrate Dextrose was introduced by Mollison
Blood was then stored in glass bottles - autoclaving etc
In 1960s CPD replaced ACD and increased shelf ife to 21 days
From here plastic replaced glass (late 60s), this facilitate separate component production
From the 70s Adenine was introduced increasing shelf life to 35 days
Finally SAGM was introduced increasing shlef life to 42 days in USA but still 35 in Europe
