Blood Transfusion 1 Flashcards
What are antigens in the context of rbc?
Protein molecules found on the surface of red cells
What happens if you give ABO incompatible blood?
Intravascular haemolysis which is potentially fatal
What proportion of the population are RhD positive and what does this mean?
85%
Can receive RhD positive or negative blood
What proportion of the population are RhD negative and what does this mean?
15%
They lack RhD antigen
Can make immune anti-D if exposed to RhD positive red cells
What are some properties of immune anti-D antibodies?
Are IgG (so cross the placenta) Do not cause direct agglutination of rbc Cause delayed haemolytic transfusion reaction
What can happen as a result of RhD negative pregnant women exposed to RhD positive blood?
Produce immune anti D which can cause haemolytic disease of the newborn or severe foetal anaemia and heart failure (hydrops fetalis) in pregnancy
In blood group testing, what is seen in a positive result in reverse testing?
Agglutination (clumping)
How are antibody screens conducted?
On patient plasma
Indirect antiglobulin technique (IAT) bridges red cells coated by IgG to form a visible clump
How is a full serological crossmatch conducted?
Indirect antiglobulin technique
Patient plasma incubated with donor red cells, will pick up antibody antigen reaction that could destroy the red cells and cause extravascular haemolysis
Agglutination = incompatible
What is an immediate spin?
Incubate patient plasma and donor red cells and spin, will detect ABO incompatibility
What are the pillars of patient blood management?
Optimise haemopoiesis
Minimise blood loss and bleeding
Harness and optimise physiological tolerance of anaemia
What are methods, particularly in surgical setting, which minimise blood loss and bleeding?
Stop anticoagulation / anti-platelet agents
Tranexamic acid
Blood sparing techniques
Cell salvage
What blood targets should be achieved pre-operatively?
Ferritin 100ug/l
TSATs 25-30%
B12>350ng/l
Serum folate >5ug/L
What are the methods pre-operatively to optimise haemopoiesis?
IV / oral iron
B12 replacement
Folate replaceErythropoietin sc
What are the storage and giving standards for RBCs?
Stored at 4oC for 35 days
Must be transfused within 4 hours of leaving the fridge
Transfer 1 unit of RBC over 2-3 hrs
What are the storage and giving standards of platelets?
Stored at 20oC for 7 days
Transfuse 1 unit of platelets over 20-30 minutes
What are the matching requirements for RBCs?
Give ABO/D compatible
Group O negative in emergency
Consider special requirements
What are the matching requirements for platelets?
ABO/D antigens weakly expressed
Should be D compatible
Consider special requirements
If group O given to A, B or AB patients select ‘high-titre’ negative (anti-A/B antibodies)
What are the matching requirements for FFP and cryoprecipitate?
Give ABO compatible (D group does not matter)
AB plasma can be given to all groups as it has no anti-A/B antibodies but is in short supply
No need to cross match but does take 30-40 mins to thaw
What are the storing and giving requirements of FFP?
Once thawed can be kept at 4oC for 24 hrs
Transfuse 1 unit over 20-30mins
What are the storage and giving requirements for cryoprecipitate?
Once thawed has to be kept at room temperature and used within 4 hrs
Transfuse 1 unit over 20-30 mins
What are examples of RBC transfusion indications?
Major blood loss - if >30% blood volume lost
Per-op, critical care - Hb<70g/L vs 80g/L
Post chemo - Hb <80g/L
What is the increment in Hb provided by 1 unit of RBC?
10g/L in a 70-80kg patient
What are some examples of platelet transfusion indications?
Massive transfusion - aim plts >75x10^9/l Prevent bleeding (post chemo) - if <10x10^9/L (<20 if sepsis) Prevent bleeding (surgery) - <50 x10^9/L (<100 if critical site: eye, CNS, polytrauma)
In what cases is a platelet transfusion contraindicated?
Heparin-induced thrombocytopenia thrombosis (HiTT)
Thrombotic thrombocytopenic purpura (TTP)
What is the rise in platelets following one adult treatment dose?
30-40x10^9/L
When is the best time to give platelets for a procedure?
Whilst the procedure is being carried out
What are the indications for FFP?
Massive transfusion - early, aim PT and APTT ratio at <1.5
Liver disease (no benefit in patients with PT ratio <1.5)
Replacement of single coagulation factor deficiency
DIC in presence of bleeding and abnormal coagulation results
Thrombotic Thrombocytopenic purpura (TTP)
What is the dose for FFP?
15-20ml/kg
4 units in 70kg man
What are the components of cryoprecipitate?
Fibrinogen fVIII and vWF Fibronectin fXIII Platelet microparticles IgA Albumin
What is the adult dose of cryoprecipitate?
2 pools (10 donors)
When is CMV negative blood required?
Intra-uterine / neonatal transfusions and for elective transfusions in pregnant women
When is irradiated blood required?
Highly immunosuppressed patients who cannot destroy incoming donor lymphocytes which can cause fatal transfusion associated graft vs host disease
When are washed cells required?
In patients who have severe allergic reactions to some donors’ plasma proteins
