HAEM: Blood transfusion Flashcards
Which blood group antibodies decline with age? What are these associated with in terms of blood transfusion?
Anti-Duffy and Kidd = these can cause delayed transfusion reactions
In GROUP testing, what type of reaction indicates that the antibody/antigen is present in the patient’s blood?
Present = agglutination at the top Absent = RBCs suspended at the bottom of vial
In SCREEN testing, what technique is used? What are the 3 components?
IAT = indirect antiglobulin technique at 37oC
Using patient serum + lab RBCs + anti-human globulin (AHG)
What type of antibodies does group vs screen testing test for ?
Group = IgM - prevent immediate reaction Screen = IgG - prevent delayed reaction
What is the result of a positive screen test?
Clumping
How is crossmatching done? What component of donor blood is used?
Plasma is used
Full crossmatch - ises IAT
Immediate spin - emergency only, detects ABO incompatibility only
Why does AGH have to be added in the screen test?
Because IgG would not cause clumping of the cells by itself like IgM does, so you wouldn’t see the positive result
Is Kell negative blood used?
Yes - for women of childbearing age
How is plasma stored?
Frozen - infused over 20-30min
Low risk of bacterial contamination as stored frozen SO if reaction occurs it’s more likely anaphylactic
Which compatibility needs to be checked for platelets and plasma transfusions?
Platelets = D only Plasma = ABO only
Why are PLATLETS given over 20-30min?
Stored at room temp so high risk of bacterial contamination
How long can FFP vs cryoprecipitate be stored once thawed?
FFP = keep 24hrs at 4oC Cryo = keep 4hrs at RT
When is transfusion indicated in…
(a) major blood bloss
(b) peri-op/critical care
(c) post-chemo
a) if >30% lost
b) if Hb <70g/L and 80g/L respectively
c) if Hb <80g/L
Name 2 CI to platelet transfusion.
HiTT (heparin induced thrombocytopenia thrombosis)
TTP
How much does 1U platelets raise plt?
30-40x10^9/L
When should you consider FFP?
Massive transfusion Liver disease Single factor def DIC bleeding TTP
What contains 2/7/9/10?
Prothrombin complex concentrate
Are FFP and plt cross-matched?
No, only group matched
What does blood irradiation do? What about washing?
Irradiation - prevents TA-GvHD
Washing - removes most plasma, platelets and WBC (useful for IgA deficient patients)
What is the RBC:FFP given in major bleeding?
1:1 usually x4 each
NB: add 50mg/kg fibrinogen if given more than 4 units
Name 2 respiratory related acute transfusion reactions.
TACO - circulatory overload
TRALI - acute lung injury
Other than TACO/TRALI, what are the acute transfusion reactions?
Acute haemolytic (ABO)
Allergic
Infective - bacterial
Febrile non-haemolytic
What is a delayed transfusion reaction?
Occurs >24hrs post-transfusion
Give 4 examples of delayed transfusion reactions.
Delayed haemolytic (Duffy, Kidd) --> alloimmunisation TA-GvHD (>2w) Infective - viral/prion/malaria Post transfusion purpura Iron overload
What does SHOT and MSBOS stand for?
SHOT = serious hazard of transfusion MSBOS = maximum surgical blood ordering schedule
What are the first signs of acute reaction to transfusion?
Temp/HR rise
BP drop
Other symptoms:
- flushing, urticaria, pain at site, itching
- headache
- collapse
- vomiting
- chest pain
How often do you monitor for transfusion reactions in an unconscious patient?
0min 15min 1hr 2hrs \+1hr etc \+end of transfusion
What is the cause of febrile NHTR? How is it managed?
Cytokine release from WBC during storage
Tx: stop/slow transfusion + paracetamol
What type of haemolysis occurs in ABO incompatibility?
Acute intravascular
What may be seen in urine in ABO incompatibility?
Haemoglobinuria (later sign)
How severe are bacterial transfusion reactions?
severe/fatal - presents like ABO incompatibility with restlessness/vomiting/flushing/collapse
What blood products are most and least associated with contamination?
plt»RBC>FFP
How long can platelets be stored?
7 days at RT
How long can RBCs be stored?
35 days at 4oC
What is the mechanism of allergic transfusion reaction? Are these reactions severe?
IgE mediated
Usually not severe except IgA DEFICIENCY (common, IgA Abs form when exposed to donor)
What is the cause of TACO and what are some signs/symptoms?
Caused by fluid overload or hypoalbuminaemia.
Sx: Fluid overload on CXR, SOB, low sats, high HR and high BP.
What is the cause of TRALI?
No clinical fluid overload but lung injury like ARDS due to ANTI-WBC antibodies in donor blood. These aggregate and stick to capillaries which causes inflammation and lung injury.
Sx: SOB, low sats, high BP and high HR, fever, bilateral pulmonary infiltrated within 6hrs of transfusion on CXR
What is the response to diuretics in TACO vs TRALI?
TACO - responds
TRALI - no
What compatibility of platelets and RBC can a patient with… receive?
a) O blood
b) AB blood
O blood can receive..
- only O RBCs
- A, AB, B, O platelets
AB blood can receive…
- only AB platelets
- A, AB, B, O blood
What platelets and RBCs can a patient with B blood receive?
Platelets: B, AB
RBC: B, O
What donors should be used for plasma platelets and why?
Male for both - not likely to be sensitised so no HLA/HNA Abs
What is the most common delayed TR and what is the consequence of this?
Delayed haemolytic = against Kell, Duffy
–> ALLOIMMUNISATION
What is the management of alloimmunisation?
Repeat group and screen
Who receives CMV negative blood?
Preg and neonates
What is the pathophysiology of TA-GvHD? How do you prevent it?
Immunosuppressed patients cannot destroy donor lymphocytes which are able to divide and destroy tissue
Prevention: irradiate blood or HLA-match
What are the signs/symptoms of TA-GvHD?
gut –> diarrhoea
liver –> failure
skin –> desquamation
and BM failure
When does post-transfusion purpura occur?
7-10 days later
Who is affected by post-transfusion purpura?
Human platelet antigen 1-ve patients
Previously immunised patients via blood or transfusion
Exact mechanism UNKNOWN
What is the management of post-transfusion purpura?
IVIG - will resolve in 1-4 weeks
How much iron in each unit of blood?
200-250mg
When is a Kleinhauer test done?
Bleeding over 20 weeks and at delivery only
What volume of fetal-maternal bleed do these anti-D doses cover for?
1) 500IU
2) 1250IU
3) 1500IU
1) 4ml
2) 10ml
3) 12ml
Other than anti-D, name 2 Abs which can cause haemolysis in a newborn.
Anti-C
Anti-Kell