Ha - Blood Transfusion Flashcards
What proteins determine blood group
ABs and Ags - ABO and RhD
What happens if ABO is incompatible
Intravascular haemolysis - can be fatal
What % of people are RhD+
85
What happens if RhD- gets RhD+ blood
Make immune anti D
What do immune anti D ABs cause
Delayed haemolytic transfusion reaction
Immune anti D ABs do not cause what to RBCs?
NOT direct agglutination of RBCs - therefore no immediate reaction, but a delayed one
Do anti D cross placenta? Why/why not?
YES - IgG so they do
What 2 tests do they do for ABO group testing
Forward group - anti A/B/D reagents against pt’s RBC
Reverse group - known A/B groups RBCs against pt plasma
Who gets other RBC Ags auto reactions
Frequent transfusers eg sickle / pregnancy
What is IAT
Indirect anti globulin technique
Bridges RBC coated by IgG, which can’t themselves bridge 2 RBCs
Forms clumps - visible after 30 mins
When can you do electronic issue of blood, and what is the benefit
Negative AB screen
Faster, fewer staffs remote work
How do you do a serological cross match
IAT - put pt plasma incubated with donors for 30 mins to observe any reaction
What is the donor blood labelled with
ABO and RhD type
Kell
Other are Ag
What is the legal requirement for all blood products
They should be 100% traceable to donor
3 pillars of patient blood management
Optimise haemopoeisis
Minimise blood loss and bleeding
Harness and optimise physiological tolerance of anaemia
How is blood loss minimised pre transfusion
Tranexamic acid
Stop anticoagulant
Cell salvage
Why should blood be given
Bleeding
Anaemic
Sx
Transfusion will solve the problem
Benefits vs risk
Alternative Tx not appropriate
Tx alternatives to blood products
Iron
B12
EPO
Folate
Cell salvage
Emergency blood
O-
How are red cells stored & given
4 degrees for 35 days
Transfuse within 4 hours of leaving fridge, IV over 2-3 hours
How are platelets stored / used
20 degrees (room temp) for 7 days
Transfuse IV over 20 to 30 mins
Do platelets have ABO/RhD
Yes - weakly expressed but not massively
What is the risk with platelet transfusion and why
Bacterial infection - stored at room temp
Do FFP/cryoprecipitate have ABO/RhD
ABO but not RhD
How is FFP/cryo stored / given
30 to 40 mins to thaw
FFP - keep at 4 degrees for 24 hours
Cryo - keep at RT and use within 4hrs
Transfuse IV over 20 to 30 mins
What type is the universal plasma donor
AB - neither ABs in
What is the maximum surgucal blood ordering schedule for / how does it work
Predicted blood loss for planned surgery to allow them to decide what is normal
Then do G&S then can do electronic issue within 10 mins when requested
Do cross match if Hx of ABs reactivity
Indicators for RBC
Haemorrhage - >30% volume lost
Peri op /crit care - hb <70
Post chemo - <80
Indications for platelets
Big transfusion aim >75
Post chemo <10
Surg <50
Plt dysfunction, only if active bleeding
When are platelets CI
HiTT or TTP
Indications for FFP
TTP
Deficiency of coagulation factors when active bleeding
How is cryoprecipitate different to FFP
More fibrinogen in cryo vs FFP
How much does cryo raise the fibrinogen by
1g/L
What is the closest used alternative to autologous blood transfusions
Cell salvage during operations
When is CMV- blood needed
Pregnant / neonates / IU
When is irrigated blood needed
Highly immune suppressed
When is washed blood needed
Severe allergic reaction to donor blood previously
% of UK that are O vs A vs B vs AB
47% O
42% A
8% B
3% AB
Acute reactions to transfusion (<24hrs)
ABO incompatible
Allergy
TACO - transfusion associated circulatory overload
Incorrect component transferred
Delayed reaction to transfusions (>24hrs)
Iron overload
GVHD
Malaria and other infections
Sx of acute transfusion reaction
Fever, rigors, chest/loin pain, collapse
Monitoring done for acute transfusion reactions
Baseline temp / pulse / RR / BP
Repeat after 15 mins
Repeat hourly
Repeat after transfusion finished
What is febrile non haem transfusion reaction inc when it occurs
During / soon after
Rise of temp by 1 degree, chills, rigors
Mx febrile non haem transfusion reaction
Slow / stop transfusion
Mx of allergy to transfusion product
Slow / stop transfusion
Antihistamines if needed
Sx of wrong blood given
Low BP
High HR, temp
Restless
Chest / loin pain
Collapse
Mx of wrong blood given
Send cross match
Call haem
Sx of bacterial contamination of blood
Restless, fever, vomiting, flushing, collapse
Low BP, high HR, high temp
In which blood product is bacterial contamination the most common and why
Platelets - kept at room temp
What is the protocol if RBCs have been out of fridge for up to 30 mins and aren’t needed anymore
Return to fridge for min 6 hours
Transfuse over max 4 hours
Cause of anaphylaxis to blood product
IgE ABs in pt cause mast cell release of granules and vasoactive substances
Most common resp complication of transfusion
TACO
What is TACO
Transfusion associated circulatory overload - fluid overload
What does TACO look like on CXR
Pulmonary oedema
When does TACO present
Within 6hours of transfusion
RFs for TACO
Cardio / resp disease
<50kg
IV fluids / fluid balance
Diuretics
CKD
Prevention of TACO
Single unit transfusion and reassess
What is TRALI
transfusion related acute lung injury
What is TRALI similar to
ARDS
Mechanism of TRALI
anti HLA ABs
Why are transfusions still only given sparingly
Still a potential risk of infection
What causes delayed haemolytic transfusion reaction (inc % of people)
1-3% of people develop immune AB to RBC Ag
Ix and results for delayed haemolytic transfusion reaction
Haemolysis screen - high BR, high LDH, low Hb
U&Es
G&S - any new ABs formed
Mechanism of TA-GvHD
Donor blood contains lymphocytes that can divide
Recipient is imm supp so can’t destroy the foreign lymphocytes
Donor lymphocytes destroy host tissues
How do you prevent TA-GvHD
Leucodepletion
Irradiation of blood products for imm supp
Prognosis of post transfusion purpura
Clears in a few weeks
Can increase bleeding
How many transfusions cause iron overload
> 50
Tx and Tx threshold for iron overload
Iron chelation (exjade tablet) once ferritin >1000
Mechanism of haemolytic disease of newborn
Foetal RBCs enter mothers circulation causing RhD anti D production if mum is RhD- and foetus RhD+
2nd preg —> anti D from mother crosses placenta and enters foetal circulation, attacking foetal RBCs if RhD+
Causes foetal anaemia and hydrous fetalis
Tx of haemolytic disease of newborn
G&S at booking and 28 weeks
If AB present - check fathers RhD status to see if baby could be RhD and monitor anti D levels in preg
MCA Doppler to monitor foetus for anaemia
Deliver early
IU transfusion to baby if needed
How to prevent sensitisation events for RhD
Always given RhD neg blood if unknown blood group / RhD- mother
Give anti D within 72hrs of sensitisation event
What are the doses for anti D
250IU if event before 20 weeks
500IU if event after 20 weeks, inc at delivery
What test is done to determine how much anti D to give
Kleihaur
