Blood Transfusion Flashcards
What 3 blood components can be taken from whole blood once it has been donated?
1) Red blood cells
2) Platelets
3) Plasma
Whole blood can be processed to give just red cells via what process?
Leucodepletion
Once whole blood has been processed to give plasma, what 3 things can this form?
1) Fresh frozen plasma
2) Cryoprecipitate
3) Undergo fractionation
Once whole blood has been processed to give plasma, it can undergo fractionation to give what 3 components?
1) Factor concentrates - FVIII, FIX, prothrombin complex
2) Albumin
3) Immunoglobulin
What is the usual transfusion time for 1 unit RBC?
1.30 to 3 hrs
What is the time limit for removal from cold storage to end of transfusion?
4hours
What must be done to the blood if its intended for rapid transfusion?
Placed in a blood warmer
The plasma which is removed to leave concentrated red cells is replaced by what?
Solution of electrolytes, glucose and adenine
Do we transfuse to normalise the Hb in anaemic patients?
No
What are the 3 reasons for transfusion RBCs?
1) Prevent the symptoms of anaemia
2) Improve quality of life of anaemic patients
3) Prevent ischaemic damage of end organs in anaemic patients
What is the cause of symptoms in anaemia?
Tissue hypoxia
What is the Tranfusion threshold trigger in anaemic patients?
The lowest concentration of Hb that is not associated with symptoms of anaemia
What are the 6 mechanisms of adaptation to anaemia?
1) Increased cardiac output
2) Increased cardiac artery blood flow
3) Increased oxygen extraction
4) Increase of red blood cell 2,3 DPG
5) Increased production of EPO
6) Increased erythropoiesis
What are the 2 main parameters which affect the adaptation mechanisms to anaemia?
1) Whether it is acute or chronic anaemia
2) Underlying conditions which affect the cardiac output, arterial blood flow or O2 saturation of Hb impair the adaptation mechanisms eg. CV disease, resp disease and age
What is the transfusion threshold (trigger) value for RBC transfusion in anaemic patients with mild symptoms?
What is the transfusion threshold (trigger) value for RBC transfusion in anaemic patients with CV disease?
What is the main reason for transfusion of RBCs?
To restore oxygen carrying capacity
What are the alternatives to RBC infusions?
1) Correction of treatable causes of anaemia - eg. iron, B12 and Folate deficiency, EPO treatment for patients with renal disease
2) Correction of coagulopathy - discontinuation of antiplatelet agents, administration of anti-fibrinolytic agents
Sometimes transfusion is used in acute anaemia due to blood loss, according to guidelines, what percentage of blood volume has to be lost for transfusion to be necessary?
> 40% transfusion is definitely necessary
30-40% transfusion is probably necessary
What is the threshold trigger value for patients on regular transfusions due to myeloid failure syndromes?
80-100g/dL
What 3 things should be taken into consideration in patients on regular transfusions for myeloid failure syndromes causing chronic anaemia?
1) Co-morbidities that affect cardiac and respiratory function
2) Iron overload
3) Adaptation to anaemia
What are the aims of transfusion in patients with chronic anaemia due to myeloid failure syndromes?
1) Symptomatic relief of anaemia
2) Improvement of quality of life
3) Prevention of ischaemic organ damage
What is the aim of transfusion in patients with chronic anaemia due to inherited anaemias (thalassaemia)?
Suppression of endogenous erythropoiesis
What is the trigger threshold for transfusion in patients with chronic anaemia due to inherited anaemias (thalassaemias)?
90-95 - target is 100-120g/L
What is the main thing to take into consideration for transfusion in patients with chronic anaemia due to inherited anaemias?
Iron overload
At what temperature are platelets stored and what is there shelf life from collection?
Stored at room temp - shelf life is 5 days from collection
What is the usual transfusion time for 1 unit of platelets?
30 mins
The adult therapeutic dose of platelets is platelets from how many pooled donations?
4 pooled donations
For what reason do we transfuse platelets?
Treatment of bleeding due to severe thrombocytopenia (low platelets) or platelet dysfunction - thus to prevent bleeding
What are the 2 contraindications for platelet transfusion in thrombocytopenia?
1) Heparin induced thrombocytopenia and thrombosis
2) Thrombocytic thrombocytopenic purpura
What is the limiting factor for the shelf life of platelets?
Risk of contamination by bacteria from donors arm which grow at the conditions of storage
What are the 3 main indications for transfusion of fresh frozen plasma (FFP)?
1) Coagulopathy with bleeding/surgery
2) Massive haemorrhage
3) Thrombocytic thrombocytopenic purpura
In what 2 situations should fresh frozen plasma not be transfused?
1) Warfarin reversal
2) replacement of single clotting factor
At what temperature is fresh frozen plasma stored, for how long?
-30 degrees - for up to 24 months
Thawed immediately before use
What is the usual dose of FFP?
12-15ml/kg (4-6 units for average adult)
In what 4 groups should you make the special requirement of using CMV negative transfusion?
1) Children
What is the purpose of giving an irradiated transfusion?
To prevent transfusion-associated graft versus host disease in specific T cell immunodeficiency cases
In what 5 groups of patients should you give an irradiated transfusion?
1) Intrauterine transfusions
2) Congenital immunodeficiencies
3) Hodgkin lymphoma
4) Stem cell/ bone marrow transplants
5) After purine analogue chemo
What are the 3 pre-transfusion laboratory tests?
1) Group - determination of ABO, Rh(D) group
2) Screen for antibodies against other clinically significant blood group antigens
3) Compatibility testing - cross matching
What is the process of the pre-transfusion Ab screen?
- Pts plasma screened for Ab against other clinically significant blood group Ag
- If negative no further testing is needed
- If positive then Ab identification is carried out: test the patients plasma against a panel of red cells containing all the clinically significant blood groups using the anti-globulin test
What is the process of cross matching pre transfusion?
- Donor red cells of the correct ABO and Rh group are selected from blood bank
- Avoid any other groups the patient has Abs against (detected in screen)
- Crossmatching: patients plasma is mixed with aliquots of donor red cells to see if a reaction (agglutination or haemolysis) occurs
What do the results of cross matching suggest?
If no reaction: RBC units are compatible and there is no risk of acute haemolysis
Reaction: RBC units incompatible, risk of acute haemolysis
What is the difference between acute and delayed transfusion reactions?
Acute reactions present 24 hours after transfusion
What are the 3 immunological acute transfusion reactions?
1) Acute haemolytic transfusion reaction due to ABO incompatibility
2) Allergic/ anaphylactic reaction
3) TRALI (Transfusion related acute lung injury)
What are the 3 non immunological acute transfusion reactions?
1) Bacterial contamination
2) TACO (transfusion associated circulatory overload)
3) Febrile non haemolytic transfusion reaction (febrile = with symptoms of fever)
What are the 2 immunological delayed transfusion reaction?
1) Transfusion associated graft versus host disease (TA-GvHD)
2) Post transfusion purpura
What is the non immunological delayed transfusion reaction?
Transfusion transmitted infection - viral/ prion (TTI)
What are the 4 diseases which we worry about infection with due to transfusion?
1) hep B (1.5 in 1 million)
2) HIV (1 in 6 million)
3) Hep C (1 in 30 million)
4) Prion disease
Acute haemolytic reaction due to ABO incompatibility results in the release of free Hb, what 4 consequences does this have?
1) Deposition of Hb in the distal renal tubule results in acute renal failure
2) Stimulation of coagulation results in microvascular thrombosis
3) Stimulation of cytokine storm
4) Scavenges NO resulting in generalised vasoconstriction
In what percentage of people is an acute haemolytic reaction due to ABO incompatibility fatal?
20-30%
What is the onset of acute haemolytic reaction due to ABO incompatibility?
Severe reactions may occur early in the transfusion - ie within the first 15 mins
Milder reactions may occur later but usually before the end of transfusion
What are the 8 signs and symptoms of an acute haemolytic reaction due to ABO incompatibility?
1) Fever and chills
2) Back pain
3) Infusion pain
4) Hypotension/ shock
5) Hemoglobinuria
6) increased bleeding (DIC)
7) Chest pain
8) Sense of impending death
What is the major cause of acute haemolytic reactions?
Always human error - biggest cause is errors of patient identification
At which 2 stages can errors of patient identification in terms of transfusion be made?
1) Sampling
2) Pre transfusion administration check - ie. check patients details on the compatibility label against the patients wrist band at the bedside
In what 3 ways can errors of identification of sampling be avoided?
1) Label at the bedside
2) Check details against the patients identification wrist band
3) Do not use addressograph labels
What is the onset of a delayed haemolytic reaction?
Onset 3-14 days following a transfusion of RBC
What are the 3 clinical features of a delayed haemolytic reactions?
1) Fatigue
2) Jaundice
3) And or fever
What are the 4 lab findings in delayed haemolytic reactions?
1) Drop in Hb
2) Increased LDH
3) Increased indirect bilirubin
4) Direct antiglobulin test positive
What is a delayed haemolytic reaction due to?
Immune IgG Abs against RBC antigens other than ABO - the Ab formed after the transfusion
In addition to ABO name the 8 important blood group systems?
1) Rhesus
2) Kell
3) Duffy
4) Kidd
5) Lutheran
6) MNS
7) Lewis
Name the 2 other names for the Coomb’s test?
1) Anti human globulin test
2) Direct anti-globulin test
What is the function of the Coomb’s test - a key test in blood transfusion - how does it work?
Used to detect IgG antibodies on red cells
1) Red cells are coated with the IgG Ab eg. anti-Rh in Rh positive patients
2) AHG (anti human globulin) added
3) Visible agglutination (as it binds the IgG bound to the RBCs)
What is the estimated rate of fatalities related to transfusion related acute lung injury?
5-10%
What is the pathological process in transfusion related acute lung injury?
1) Donor has Ab to recipients leucocytes (anti-HLA, anti-HNA)
2) Activated WBC lodge in pulmonary capillaries
3) Release substances that cause endothelial damage and capillary leak
Transfusion related acute lung injury (TRALI) tends to be a complication of which kind of transfusion?
Of plasma rich components eg. platelets or FPP
What is the criteria for diagnosis of TRALI?
Sudden onset of acute lung injury occurring within 6 hours of transfusion
What are the 3 features of acute lung injury?
1) Hypoxemia
2) New bilateral chest X ray infiltrates
3) No evidence of volume overload
What is the treatment for TRALI?
Mild forms may respond to supplemental oxygen therapy
Severe forms may require mechanical ventilation and ICU support
There is no role for diuretics or corticosteroids
What confirms the diagnosis of TRALI?
Lab investigations = donor tested fro HLA and granulocyte Ab and the recipient is tested for expression of neutrophil Ag
Confirmation of diagnosis = donor has Ab against Ag that are expressed on recipients granulocytes
After how many hours do people with TRALI usually recover?
72-96 hours
What are the 7 signs and symptoms of transfusion-associated circulatory overload (TACO)?
1) Sudden dyspnea
2) Orthopnea
3) Tachychardia
4) Hypertension
5) Hypoxemia
6) Raised BP
7) Elevated jugular venous pulse
What are the 5 risk factors for TACO?
1) Elderly patients
2) Small children
3) Patients with compromised LV function
4) Increased volume of transfusion
5) Increased rate of transfusion
What are the 2 main allergic reactions patients can experience with transfusion?
1) Urticarial rash +/- wheeze - hypersensitivity due to a random plasma protein
2) Anaphylaxis - wheeze, tachycardia, hypotension, laryngeal oedema, facial oedema
What 2 lab investigations should be undertake when a patient has an allergic reaction to transfusion?
1) Quantification of IgA
2) testing for anti-IgA Ab
What is a febrile non-haemolytic transfusion reaction (FNHTR?
Occurs during or soon after transfusion
Get a fever-rise in temp >1 degree +/- shakes/ rigors
Sometimes get tachychardia
This is unpleasant but not life threatening
What are FNHTRs due to?
Cytokines or other biologically active molecules that accumulate during the storage of blood components
