Blood Transfusion Flashcards
What is the process by which whole blood is filtered and white blood cells removed?
Leucodepletion
What are the main constituents of whole blood?
RBC
Platelets
Plasma:
- Fresh frozen (
What is the process by which the main constituents of whole blood separated?
Centrifugation
How much in ml is one unit of RBC?
275ml
What are the storage conditions for RBC storage?
4 degrees for up to 35 days
Plasma is removed and replaced by solution of electrolytes, glucose and adenine - keeps RBC healthy
From removal from cold environment, what is the time limit for blood transfusion? How long does it take
within 4hrs
Between 1.5-3 hrs
Why do we transfuse patients?
To prevent symptoms of anaemia
Improve quality of life
Prevent ischaemic damage
NOT normalise Hb (Hb conc will remain the same, just number of RBCs will be lower)
What are the symptoms of anaemia the result of?
Tissue hypoxia
At what point should a blood transition be given (transfusion threshold)?
The lowest concentration of Hb where symptoms of anaemia are not observed
Name the mechanisms by which the body adapts to anaemia (i.e. maintain tissue oxygenation)?
- Increased cardiac output
- Increased 2,3 DPG
- Increased cardiac artery flow
- Increased EPO production
- Increase erthroproiesis
- Increased O2 extraction
what factors are used to determine the transfusion threshold of patients?
Acute vs chronic - less time for adaptation mechs to develop so termite anaemia less well
Underlying conditions - resp, CV, age - tolerate anaemia less well
Why are RBCs transfused?
To restore oxygen carrying capacity
What are the transfusion thresholds for patients and patients with CV disease who have mild symptoms of anaemia?
When are RBC transfusions to given?
Individuals with preventable causes of anaemia e.g. iron, B12, folate deficiency, renal disease (erythropoietin therapy is choice treatment)
Individual requiring correction of coagulopathy
Which blood loss, what is the amount of blood loss required to necessitate a transfusion?
> 2000 ml
What is the transfusion threshold level for individuals with chronic anaemia?
Hb 80-100 g/L
- set individual threshold and set Hb concentration targets
What considerations should we have for individuals receiving blood transfusions?
Iron overload - avoid over transfusion
Causes cardiomyopathy and liver failure
What is the transfusion threshold for individuals receiving regular transfusions due to inheritable conditions? What is the objective of this?
Hb 90-95 g/L
- avoid iron overload
- Suppression of endogenous erythropoiesis
What are the optimum storage conditions for plasma?
22 degrees, 5 day shelf life
How long does it take to transfuse plasma?
30 mins/unit
Why are platelets transfused?
Thrombocytopenia/platelet dysfunction
-Prevention of bleeding
What are the contraindications for platelet transfusion?
Heparin induced thrombocytopenia and thrombosis
Thrombotic thrombocytopenia purpura
What are he storage conditions/shelf life for fresh frozen plasma?
- 30 degrees
- 24 months
- Thawed for 20-30 mins immediately before use
- takes 30 mins to transfuse
How many units does an average adult require?
4-6 units (12-15mg/kg/unit)
What are the main indications for use of fresh frozen plasma?
Coagulopathy with bleeding/surgery
Massive haemorrhage
Thrombotic thrombocytopenia purpura
What patients is Fresh frozen plasma not used?
Individuals with warfarin overdose
Individual with single factor deficiency
What are the some special requirements for transfusions?
CMV negative - protect at risk patients from CMV e.g. pregnant women,
Pre trans lab testing. What comprises the group and screen process?
Test donors ABO/Rh(D) group
-Test patient plasma for antibodies against clinically significant blood group antigen
What comprises the pre transfusion lab testing of ‘crossmatching?’
Correct donor ABO/Rh groups are selected for patient
Donor blood is mix ed with patient plasma to see if there is any reaction e.g. haemolysis/agglutination
Reaction = incompatible; risk of haemolysis
What are the risks of transfusion? how are they classified?
Acute/chronic
Immunological/non-immunological
Name so acute immunological conditions associated with blood transfusion
ABO incompatibility (acute haemolytic transfusion reaction)
Allergic/anaphalaxic reaction
Name some acute non-immunological conditions associated with blood transfusion
bacterial contamination
Name some chronic immunological reactions due to transfusion
Transfusion associated graft vs host disease
Post transfusion purpura
Name some chronic non-immunological reactions due to blood transfusion
Transfusion transmitted infection
Virus e.g. HIV/prion disease
What is the main cause of symptoms in acute haemolytic reaction with ABO incompatibility?
Free Hb in blood
What are the symptoms of Acute haemolytic reaction - APO incompatibility
Fever and chills Back pain Infusion pain Hypotension/SHOCK HAEMOGLOBURIA (Hb in urine) Increased bleeding (DIC)
What type of error is acute haemolytic reaction (APO compatibility)? When does it most likely occur?
ALWAYS human error
Most likely with blood administration
What are the clinical features of delayed haemolytic syndrome?
Fatigue
Jaundice
Fever
What are the lab findings associated with delayed haemolytic syndrome?
- Reduced Hb
- Increase Lactate dehydrogenase
- Increase inactive bilirubin (hence jaundice)
What is delayed haemolytic syndrome caused by?
IgG antibodies that react to antigens other than those of ABO. Occurs 3-14 day post transfusion
What is the Coombs test used for? How does it work?
Used to test for presence of antibodies on RBCs (delayed haemolytic syndrome)
Antihuman globulin added to blood - agglutination = positive for antibodies
What is transfusional related acute lung injury? How is it treated?
Antibodies against recipients leukocytes/granulocytes are present in donor blood. Causes damage to lung endothelium and capillaries.
Supportive treatment O2/ventilation
