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
What is meant by the storage lesion?
2,3-DPG levels fall to zero in approximately 2 weeks
The oxygen dissociation cruve shifts to the left
ATP levels also fall to about 50% of initial values
Both ATP and DPG can be regenerated following transfusion
What does 2,3-DPG stand for?
2,3-disphosphoglycerate
Ho long does it take DPG levels to fall to zero?
Only takes 2 weeks
How long does it take to regenerate DPG and ATP in a pack following transfusion?
It only takes 12 to 24 hours for levels to return to normal hence why old blood is perfectly okay for top up transfusions
Why can the storage lesion be dangerous?
Its dangerous in massive transfusion of short dated blood especially in patients with cardiovascular disease
ATP falls and DPG falls -> transfused rbcs wont be able to push out oxygen efficiently
What are the effects of storage on red blood cells, what increases and what decreases?
Increases:
- plasma haemoglobin
- plasma K+
Decreases:
- viable cells
- plasma pH
- plasma Na+
- RBC ATP + 2,3 DPG
What physical changes happen to red blood cells upon storage?
There is a loss of membrane lipids
Haemolysis gradually occurs-usually insignificant
Plasma K+ raised particularly if units are irradiated
Na+ decreased
Both of these changes reflect poor performance at low temperatures of ATPase which acts as a pump for Na and K
Loss of platelets
Loss of labile clotting factors
Change from disc to echinocyte to sphere
What happens to the shape of red blood cells as theyre stored?
Disc to echinocytes/acanthocytes to spheres
As red blood cells change shape their biochemical properties change
This shapae change is not reversible
How are red blood cells stored?
Stored only between 2 and 6 degrees (4 degrees usually) -> refrigerated for 35 days
Temperature monitored with audible alarm systems
Inventory control to minimise blood waste
First in, first out
Re routing especially of O Negs etc
For who shouold blood less than 5 days old be used or and why is this?
Neonates
Cardiovascular surgery
This is due to potassium leakage from cells over time, high potassium can cause cardiac arrest in these patients
Talk about how a blood fridge should be organised
Interior should be well organised and segregated into:
- uncrossmatched blood
- blood being crossmatched
- crossmatched labelled blood
- rejected, outdated or quarantined blood
- autologous blood
What does FIFO sand for?
First in first out
How is massive transfusion defined?
(4)
Replacinement approximating or exceeding the patient’s blood volume within a 24 hour period
An ongoing transfusion requirement in an adult of more than 150ml per minute
Replacement of more than 50% of blood volume in 3 hours or less
Replacement of ones blood volume or transfusion of 10 units or more or red cells in a 24 hour period
What can be some issues with massive transfusions?
Need to have established procedures for emergency provision of blood
Typical issues would be group O rather than ABO specific and these might be stored in satelite locations
Talk about major haemorrhage packs
There are different packs for major haemorrhages e.g. pack 1, pack 2 etc
Different hospitals will have different components in their packs depending on the hospital e.g. for maternity for post partum haemorrhage etc
Talk about the trends in postpartum haemorrhage
The rate of PPH per 100 deliveries have increased in the past 10 years, from 5,0 in 2011 to 8.0/100 in 2018
Talk about trends in major obstetric haemorrhage in Ireland
Trending upwards
was 2.4/1000 in 2011 but now 3.7/1000 in 2018
Talk about trends in transfusions during childbirth over the years
Trending upwards
Was 1.4 in 2011 but no 2.1/100 in 2018
What is the treatment for post partum haemorrhage?
transexamic acid + fibrinogen
