Blood transfusions Flashcards
Why should prescribing blood products be taken seriously?
- Transfusion reactions are common even with cross-matched blood
- Blood products are scarce so should be used only when necessary
- Blood group incompatibility is life-threatening complication
What are the NICE guidelines recommendation for haemoglobin concentration for those who need RBC transfusion and the concentration target after tranfusion?
- Restrictive Hb concentration for those who need RBC transfusion
- 70g/L
- Hb concentration target after transfusion
- 70-90g/L
What are the important blood groups to consider when prescribing blood products and cross-matching?
- ABO blood system
- Group D of rhesus system
What are the Rhesus D (RhD) classifications in patients
- RhD+ or RhD-
- Depends on presence of rhesus D surface antigens
- RhD+ (85%): RhD antigens present
- RhD- (15%): RhD antigens absent
What happens if a RhD- patient is given RhD+ blood?
- RhD- patient will begin to produce RhD antibodies
- Will not matter for the patient
- Cannot go onto attack their own RBCs because they do not have RhD present on the RBC membrane
What happens if a RhD- patient becomes pregnant with a RhD+ fetus (RhD+ partner)?
- Causes Haemolytic Disease of the Newborn (HDN)
- Feotal blood is RhD+ => mother creates RhD antibodies
- Second pregnancy with RhD+ child
- Anti-D antibodies cross placenta and enter foetal circulation and bind to RhD antigens on the feotal RBC surface membranes
- Fotal immune system attacks its own RBCs leading to foetal anaemia
What type of RhD blood is given to men and women?
- Women
- Given RhD specific blood to avoid HDN
- Men
- Preferable to give cross-matched blood
- Possible to give RhD+ blood to a RhD- male in emergency setting
Describe the ABO blood group?
- Refers to the presence of A / B antigens on the surface of RBCs
- People produce antibodies to bind to the surface antigen (A or B) that are NOT present on your own RBC membrane
- Important consdieration for O- and AB+ blood
Describe the considerations for O- blood?
- Universal donor
- Blood can be given to anyone because there are no AB or Rhesus antigens on donor RBC surface membrane
- They are unlikely to reject this blood as there are no ABO of Rh antigens to attack
Describe the considerations for AB+ blood?
- Universal acceptor
- They can receive any donor blood as they do not have any A, B or rhesus antibodies in their circulation so cannot mount an immune response to donor blood
Table of the different blood types and their antigens
- Blood group A
- What antibodies do they have in plasma?
- What antigens do they have in RBCs?
- What blood types are compatible in an emergency?
- Anti-B
- A antigen
- Groups A and O
- Blood group B
- What antibodies do they have in plasma?
- What antigens do they have in RBCs?
- What blood types are compatible in an emergency?
- Anti-A
- B antigen
- Groups B and O
- Blood group AB
- What antibodies do they have in plasma?
- What antigens do they have in RBCs?
- What blood types are compatible in an emergency?
- None
- A and B antigens
- Universal recipient
- Blood group O
- What antibodies do they have in plasma?
- What antigens do they have in RBCs?
- What blood types are compatible in an emergency?
- Anti-A and anti-B
- No antigens
- Can only receive group O
What are the two blood tests that should be preformed prior to blood transfusion?
- Group and save (GC&S)
- Crossmatch
Describe GC&S?
- Determines patient’s blood group and screens for atypical antibodies
- GC&S is recommended if blood loss is not anticipated but blood may be required if there is greater loss than expected
Describe the crossmatch blood test?
- Involves mixing patient’s blood with donor blood to see if an immune reaction takes place
- G&S should be done first
- Recommended if blood loss is anticipated
Describe the process of requesting blood products?
- 3 points of identification (name, DOB, CHI no)
- Consent patient
- Label bottles at the bedside
- Complete transfusion request form at the bedside
Describe CMV negative blood products?
- CMV is common congenital infection
- Can cause sensorineural deafness and cerebral palsy
- => CMV negative blood should be given to women during pregnancy, intra-uterine transfusions and neonates
Why are blood products irradiated?
To reduce graft-versus-host disease in at risk populations
Name some patient groups who should receive irradiated blood products?
- Receiving blood from first or second degree family members
- Patients with Hodgkin’s lymphoma
- Recent haematipoietic stem cell transplants
- People receiving purine analogues as chemotherapy
Describe the administration of blood products?
- If receiving more than one unit, they should be prescribed individually
- Important observational timings:
- Before transfusion
- 20 minutes
- 1 hour
- At completion
- Admimnstered via green or grey cannula
Why should blood be given via large cannulas?
Otherwise the cells will haemolyse due to sheering forces in a narrow tube
What are the different parts that a donor’s blood is separated into?
- Packed red cells
- Platelets
- Fresh frozen plasma (FFP)
- Cryoprecipitate
How are blood products administered?
- Via blood giving set
- Has a filter in the chamber which a normal fluid giving set lacks
Major constituents of packed red cells?
Red blood cells
Indications for packed red cells?
- Acute blood loss
- Chronic anaemia where Hb <70g/L or <100 in CVD
- Symptomatic anaemia
Duration of packed red cells administration?
- 2-4 hours
- Must be completed within 4 hours of removal from the store
Considerations for giving packed red cells?
- 1 unit of blood should increase Hb by 10g/L
- Patient RBCs may produce autoantibodies to donor surface antigens
- New G&S should be sent before starting another transfusion
Indication for giving platelets?
- Haemorrhagic shock in trauma patient
- Profound thrombocytopenia (<20 x109/L)
- Normal 150-400)
- Bleeding with thrombocytopenia
Duration for the administration of platelets?
30 minutes
Describe an adult therpeutic dose of platelets?
Should increase platelet levels by 20-40 x109/L
Constituents of FFP?
Clotting factors
Indications for FFP?
- Disseminated intravascular coagulation (DIC)
- Haemorrhage secondary to liver disease
- All massive haemorrhages
- (given after 2nd unit of packed red cells)
Duration of administration of FFP?
30 minutes
Major constituents of cryoprecipitate?
- Fibrinogen
- Von-Willebrands factor (vWF)
- Factor VII
- Fibronectin
Indications for cryoprecipitate?
- DIC with fibrinogen <1g/L
- Von willebrands disease
- Massive haemorrhage
Duration of administration of cryoprecipitate?
Stat
General complications of red cell transfusions?
- Clotting abnormalities
- Electrolyte abnormalities
- Hypothermia
Describe the clotting abnormalities caused by packed red cell transfusions?
- Due to a dilution effect
- The packed red cells do not contamin platelets or clotting factors
- To reduce the risk of impairment, FFP, platelets should be administered concurrently in patients receiving more than 4 units of RBCs
Describe the electrolyte abnormalities caused by packed red cell transfusions?
- Hypocalcaemia
- chelation of calcium by calcium binding agent in preservative
- results in reduced serum calcium level
- Hyperkalaemia
- due to partial haemolysis of RBCs and resultant intracellular potassium release
Describe the hypothermia caused by packed red cell transfusions?
- Blood products are thawed from frozen then kept and cool temperatures
- They may not be at body temperature at the time of transfusion
Name the ACUTE complications from transfusions?
- Anaphylaxis
- Acute haemolytic reaction
- Transfusion associated circulatory overload
- Transfusion related acute lung injury (TRALI)
- Form of ARDs, non-cardiogenic pulmonary oedema
Name the DELAYED complications from transfusions?
- Infection
- Risk of HBV, HCV, HIV, syphilis, malaria
- Less concern now blood donors are screened
- Graft vs Host Disease (GvHD)
- Fever, skin involvement, diarrhoea, vomiting
- Iron overload
- Patients receiving multiple transfusions (thalassemia)
