W3 LECT 2: introduction to blood tranfusion Flashcards
what are the most RBC important antigens?
- ABO
-Rh - DUFFY
what is the Landsteiner’s rule in ABO blood group system?
“Whenever an antigen is lacking on the red cells, the corresponding
antibody is found in the serum
what are the 4 blood groups of the ABO blood group system?
- Group A
- Group B
- Group O
- Group AB
what are the 4 phenotypes?
- A, B, AB, O
- A and B are co- dominant, O is recessive
what are the 6 genotypes?
- AA, AO
-BB, BO - AB
- OO
Classify the antibodies found in serum
Group A: A, Anti-B
Group B: B, Anti-A
Group O: - , Anti-A+ Anti-B
Group AB, A+B, -
what is forward grouping?
WHAT ANTIGENS ARE SITTING ON THIS RED CELL
* Forward grouping:
(testing unknown RBC)
+ means agglutination/ reaction
0 means no agglutination/ reaction
what is reverse grouping
WHAT ANTIBODIES ARE IN THIS SERUM
- Identifies unknown antibodies in the serum using “known antigens” (A cells and B cells)
what happens when the antibodies in the pt’s plasma react with ABO incompatible donor RBC ?
- agglutination
- massive haemolysis
what makes antibodies ro rbc antigen to be considered clinically significant?
- Haemolytic transfusion reactions (acute and delayed)
- Autoimmune haemolytic anaemia
- Haemolytic disease of the fetus and newborn
differentiate between universal donor and recipient?
-blood group O (Rh negative) = Universal donor (RBC from group O will not
react with serum from persons who are A or B)
* Blood group AB (Rh positive) = Universal recipient (persons with group AB
have no antibodies in their serum so they can receive blood of any ABO type)
what is the plasma composed of?
- Liquid portion blood
- Light yellow
- Contains water, salt, enzymes
- Contains clotting factors and is usually given to replace clotting
factors
what antigens are found in thr rh blood group system?
D, C, c, E, e
what genes code the rh antigens?
- RHD: results in D antigen
- RHCE: results in C,c, E, e
what are the +/- Rh antigens?
Rh +: Rh D, rh CE
Rh -: -, Rh Ce
when are antibodies produced in Rh?
Antibodies are produced only on exposure to antigen
* Blood transfusion (Rh+ blood transfused to Rh- recipient)
* Fetomaternal haemorrhage (Rh+ fetus, Rh- mom)
what are the pre- transfusion testing for red cell transfusion?
- ABO (Rhd) typing
- screen serum/ plasma of pts to look for clinically significant antibodies
- crossmatching
what are the appropriate use of blood products?
Use alternatives to allogeneic transfusion when appropriate
-Medical alternatives
* e.g. Oral or IV iron for iron deficiency anaemia
* Human recombinant erythropoietin (EPO)
* DDAVP (type I VWD, mild Haemophilia A)
* Tranexamic acid
- Autologous blood donation
* pre-op (elective surgery, well pt)
E.g. of transfusion of blood products
-Whole blood
-Red cell concentrate (packed cells)
* Transfused to increase Hb
-Platelet concentrate
* Transfused to increase platelet count and/or to provide functional
platelets
- Fresh frozen plasma
* Transfused to provide stable coagulation factors
- Cryoprecipitate
* Transfused to provide fibrinogen
outline the red cell concetrate:
- Stored for up to 42 days at 2 - 6°C
- Usually indicated if HB <6g/dl
- Rarely indicated if HB >10g/dl
- Patient specific (age, co-morbidities, rate and vol of blood loss, risk of
ischaemia)
what are the 2 sources of ptls?
- Buffy coat layer of whole blood (4-5 donations are pooled)
- Single donor apheresis (split into 2-3 bags)
- stored at room temperature (22oC) for up to 5 days
when are ptls used?
- Bone marrow failure
- Therapeutic (bleeding and thrombocytopenia, usually <20 x109/L)
- Prophylactic (PLT< 20 x109/L or <10 x109/L)
- Acute leukaemia
- <10 x 109/L (higher if sepsis, antibiotics, DIC)
- APL: <20 x 109/L
- BMAT: not required regardless of plt count, apply local pressure post procedure
when shoul ptls be used? continued
- LP, epidural anaesthesia, gastroscopy and biopsy, inserting indwelling
lines, transbronchial biopsy, liver biopsy: >50 x 109/L - Brain/ eye procedures: >100 x 109/L
- Massive transfusion: >50 x 109/L (>100 x 109/L for multiple trauma/ CNS
injury) - DIC: maintain at 30-50 x 109/L
contraindication of platelet use?
- autoimmune thrombocytopenia
- ttp: thrombotic thrombocytopenic purpura
- hit: heparin induced thrombocytopenia
what are the characteristics of fresh frozen plasma?
- Separated from whole blood within 18 hours of donation
- Frozen at -18C
- Contains all clotting factors at physiological levels
- Volume of an adult FFP unit: 240-300ml
- Usual dosage 10-15 ml/kg
- Administered through a blood giving set after thawing at 30-37C
- Rapid transfusion (15 -20 minutes per unit)
- Use within four hours of thawing
- ABO compatible (if using ≥5 units)
- Group O should only be given to group O
indication of ffp?
Indications:
* Multiple coagulation factor deficiencies
* DIC
* Massive blood transfusion
* Liver disease
* TTP
* Reversal of warfarin if prothrombin complex concentrate not available
* Haemorrhagic disease of newborn secondary to Vit K deficiency (if actively
bleeding)
* Replacement of inherited single factor deficiencies where specific factor not
available
what is croprecipitate?
Insoluble fraction of FFP
* Stored below -18C
* Contains:
* F8/VWF
* Fibrinogen
* Fibronectin
* Factor 13
what are the indications od cryoprecipitate?
Indications:
* Congenital hypofibrinogenaemia
* Acquired hypofibrinogenaemia (DIC, massive transfusion, obstetric
haemorrhage fibrinogen <1.5g/L)
* Dysfibrinogenaemia
* Dosage: 1 unit /10kg body weight (8-12 units in an adult)
leucocyte depleted products?
Leucocyte depleted products:
* Filter to remove most leucocytes
* Expensive
* Available on request in South Africa
* Possible transplant patients
* Previous FNHTR
* Decreased risk of CMV infection in susceptible recipients (neonates)
* Chronic transfusion regimens
* Infants < 1 year
how are blood specimen collected and stored?
- dentify the patient
- Label the specimen
- Check expiry dates of tubes
- Collect adequate sample - the tube must
be filled ¾. Please contact the blood bank for the minimum volume needed for
paediatric patients. - Record date and time of specimen collection
- Sign on both the label and relevant area on the “Request for Blood or Blood components” form (“drawn by..”)
- Send sample and request form to the blood
bank ASAP. - Store specimen in appropriate cold chain
conditions. PS: Samples should not be older than 48 hours, but the fresher the sample the better - record blood request in the pts’ file
what do write on the pts’ request form
- full name of the pts and DOB
- pts’ unique hospital number
- financial classfication
- name of the hospital and ward
