Blood Transfusion Flashcards
Blood groups
Arise form antigens. Red cell antigens are expressed on the cell surface (proteins, sugars, lipids). These are determined genetically.
Type O
Absence of antigens
ABO blood group antigens
ABO gene encodes glycosyltransferase. Glycans added to proteins or lipids on Red Cells
A and B genes code for transferase enzymes
A antigen is N-acetyl-galactosamine
B antigen is galactose
‘O’ gene is non-functional allele
So A and B are (co-)dominant and O is recessive
Blood group antibodies
These can be due to immune tolerance or IgM (anti-A/B naturally occurring antibodies which are developed via gut bacteria in the first few weeks of life)
A
42%
B
9%
AB
3%
O
46%
Universal donor
Blood type O can be received by any patient
Universal recipient
Blood type AB
Universal donor of FFP
AB
Blood group O FFP
unsafe from all donors
RhD blood group system
RhD and RhCE (homologous to RhD) Next immunogenic system. A transmembrane protein which is very immunogenic. Acts as classic antigen. Will not make antibody unless you’ve seen it before. Large proportion of the population are Rhdd (RhD negative)
Anti-RhD
RhD negative individuals can make anti-D if exposed to RhD+ cells
Transfusion or pregnancy
Anti-D can cause transfusion reactions or haemolytic disease of the newborn
Blood donors
Extensive ‘behavioural’ screening
Sex, age, location…………
Tested for ABO and Rh blood groups
Screened for HepB, HepC, HIV, syphilis (sometimes screened for other infections depending on travel)
Plasma
Fresh frozen plasma (frozen, if require clotting factors this can be put in immediately)
Cyroprecipitate (rich in factor 8, mixed with alcohol, rich in fibrinogen)
Factor concentrates, immunoglobulin and albumin
Red Cells
Stored at 4oC
Shelf life 35 days
Transfuse over 2-4 hrs
Indications for tranfusion of red cells
Surgery, obstetric, trauma
Medical: GI haemorrhage, bone marrow failure, chemotherapy, severe anaemia refractory to other therapy
Other: HDN, sickle cell anaemia, thalassaemia etc etc
Platelets
Cool platelets from four donors together and stored for 5 days. Transfuse over 20-60 minutes.
Indications for platelets
Massive haemorrhage
(Keep platelet count above 75x109/l)
Bone marrow failure
(platelet count <10-15 × 109/litre
or <20 × 109/litre if additional risk, e.g. sepsis)
Prophylaxis for surgery
(Minor procedures 50x109/l;
More major surgery 80x109/l; CNS or eye surgery 100x109/l)
Cardiopulmonary bypass (Platelets should be readily available, use only if bleeding)
Fresh frozen plasma
1 unit from 1 unit of blood
Stored frozen, allow 30 minutes to thaw
Indications for FFP
massive haemorrhage (use in 1:1 ratio?), coagulation factor replacement.
DIC with bleeding
Liver disease - in the presence of bleeding or prior to invasive procedures
Use prothrombin complex concentrate for warfarin reversal
Lab test for FFP
PT and APTT
Cryoprecipitate
2 pools if fib <1.0g/dl (1.5g/dl)
Stored frozen; allow 30 minutes to thaw
Lab test for cyroprecipitate
Fibrinogen
“Practical Blood Banking”
Blood sent to lab
‘Second sample’ now implemented
Group and Save
Cross match
-Tariff defined by ’MSBOS
Samples kept for 7 days
-but only valid for 2 days if recent transfusion
Blood Grouping and Antibody Screening
ABO and RhD type
Checked against historical records
Screen for allo-antibodies in serum
Coombs Test
Direct anti-globulin test, whether there is antibody attached to the surface of cells. Anti-human immunoglobulin is added.
Direct Coombs Test
autoimmune haemolytic anaemia
passive anti-D
haemolytic transfusion reactions
Indirect Coombs Test
Cross matching. Serum from the plasma and then the Coombs Reagents
Red Cell Availability
Minutes – O RhD Neg red cells, AB plasma and group A plasma
Urgent – Type specific (ABO/ RhD)
Non-urgent – Full cross match, select correct ABO/RhD type. If allo-antibodies choose antigen negative blood.
Massive Haemorrhage Policy
Immediate supply of:
6 units red cells
4 units FFP (cryoprecipitate?)
1 unit platelets
Risk of Transfusion
Death or harm (transfusion or ABO incompatible components)
Tranfuscion associated cardiac overload (left ventricular failure)
Transfusion associated lung injury
Acute transfusion reaction
Febrile ractions
Allergic reactions
Minor reactions to blood
Fever usually below 38 degrees, urticarial rash
Treat with paracetamol and antihistamine
1% of transfusions
Major reactions to blood
Fever, urticaria, respiratory distress, hypotension, tachycardia, oliguria, bleeding and collapse
Management of reactions
Stop transfusion
Check patient identity
Consider: anaphylaxis, circulatory overload (TACO), acute haemolytic transfusion reaction (AHTR), bacterial infection, lung injury (TRALI) (other…)
Treatment of TACO
Slow rate, IV diuretic (20mg of furosemide) , and oxygen
ABO Haemolytic Reactions (acute)
immediate, complement mediated lysis or IgM or IgG complement fixing
Shock, high fever, renal failure
Treat with O2, IV fluids, diuretics, inotropes, dialysis
Delayed Haemolytic Reactions
Due to IgG antibodies. Anaemia and jaundice 7-10 days post-transfusion. Do positive direct anti-globulin test (COOMBS test)
Bacterial Infection
Platelets. Treat with IV antibiotics, O2 and IV fluids.
TRALI
Oxygen, respiratory support and IV fluids. Notify the blood service to investigate/initiate recalls.
Prion Disease
Transmittable by blood transfusion from early in disease in sheep. New variant Creutzfeldt-Jakob disease.
Development of Maternal AntiD antibodies
Haemolytic anaemia resulting from IgG crossing the placenta in subsequent pregnancies. Presents with anaemia and jaundice. Give Anti-D just before birth. All mothers screen, if they are negative they are tested for antibodies against it. Check dopplers, increased blood flow treated with RhD- cells
Neonatal Alloimmune Thrombocytopenia similar process for platelets
bleeding and thrombocytopenia in the first few days after birht
Leucapheresis
Bone marrow harvest, donor lymphocyte infusions.
Process of of blood grouping
Red cell group is determined by suspending washed red cels with diluted anti-A, anti-B, anti-AB and anti-Rh(D). Agglutination indicates a positive test.
Compatibility testing
This entails suspension of red cells from a donor pack with recipient serum, incubation to allow reactions to occur and examination for agglutination, including an indirect antiglobulin test to ensure that no reaction has occured.
Indications for use of cyroprecipitate
DIC, liver disease, von Willebrand disease
