Practical aspects of transfusion Flashcards
the aim of pre transfusion testing
provide red cells for transfusion that will survive normally in recipients circulation
to avoid haemolytic transfusion reactions
Steps in ensuring safe transfusion
correct identification, sampling and labelling
Determination of the ABO and Rh(D) type of the recipient
antibody screen designed to detect clinically significant antibodies
Selection of appropriate red cells for transfusion
A final cross match or compatibility test
Removal of selected red cell units from blood refrigerator
final identity check at bedside
common sources of transfusion error
wrong patient sample
lab procedures
blood issuing and collection
wrong blood wrong patient
The pre-transfusion sample procedures
Patient ID - confirmed by asking the patient (if conscious and coherent) to state their given names and DOB, and by checking their identity label
Sample labelling - done at bedside, preprinted labels not accepted
Confirmed on request form - check information on the sample label and wristband are correct before leaving the patient
The 3 steps of pre-transfusion testing
Determine ABO and Rh(D) type of recipient
- known patient compared to historical record
- Unknown patient checked twice
Antibody screen
- Specifically selected cells that will enable identification of clinically significant antibodies
- Anti human globulin technique
Selection of blood component
Blood ordering policies
Group and screen
Compatibility testing
Emergency situations
Group and screen
in surgical settings when likelihood of blood being required is low
Antibody screen should be negative
serum retained in lab for 7 days
Red cells can be provided quickly when needed (within 5 mins)
Compatibility testing
3 board approaches
- Full crossmatch
- AGH testing
- Progressive decline in use
- Used primarily when antibody screen is positive - Immediate spin cross match (5-10mins)
- Aims to detect ABO compatibility - Computer crossmatching (5 mins)
- Final ABO check performed electronically
Emergency situations
Effective communication essential 3 main approaches, sequential Emergency O, Rh(D) negative units - Requirement for blood desperate, patient group not known - Group specific blood Provision of fully compatible blood
Final bedside check
Common form of error should involve two people check patient identity against compatibility label - Full name - DOB - NHI - Blood group
Monitoring transfusion / what to do when things go wrong?
Monitor patient closely Major problems likely to produce early warning signs If symptoms develop - stop transfusion - Maintain line with saline - Seek advice
immunological complications of transfusions
early - haemolytic reactions - febrile non haemolytic reactions - TRALI - Reactions to proteins Late - Delayed haemolytic reactions - Post transfusion purpura - Graft versus host disease
Non-immunological complications of transfusion
Bacterial and viral transmission
What is an immediate haemolytic reaction?
Red cell rupture from antibody attack = leaking of Hb into plasma
What happens when small fragments of compliment liberated vs hemolysis
symptoms and signs including hypotension –> acute renal failure –> symptoms associated with circulatory failure
Whereas hemolysis ends up like disseminated intravascular coagulation
Immediate haemolytic reaction
- symptoms
- signs
symptoms - fever - restlessness - retrosternal or lion pain Signs - increased temperature - Hypotension - Uncontrolled bleeding
Delayed haemolytic transfusion reaction
Classically occurs 7-10 days post transfusion
Patient Hb fall associated with slight jaundice
Anamnestic / memory response
- sensitisation by previous transfusion or pregnancy
- antibody not detectable during pre transition testing, but in memory B cells in lymph nodes
potentially avoidable
Immediate Intravascular haemolytic reactions
ABO incompatibility Main complications - renal failure - DIC 30% long term morbidity, 10% mortality usually preventable
Extravascular haemolytic reactions
IgG antibody in patient plasma
- Rh antibodies, Kell, Kidd, Diffy etc
Complement activation
- Does not occur
Clinically indistinguishable from acute intravascular haemolysis
Sometimes you will even get hemoglobinurea from leakage of products of red cell destruction by the spleen and liver
Febrile non- haemolytic transfusion reactions
relatively common
Fever > 38 degrees usually starting during transfusion
Often associated with rigors
clinically often indistinguishable from haemolytic reactions
Pathophysiology of FNHTR
classically caused by white cells in red cell component
presence of antibodies to white cells e.g. HLA antibodies in the recipient
Management of FNHTR
Stop transfusion Maintain line Investigate Take blood cultures Medication - paracetamol - Antihistamine - Hydrocortisone
Transfusion related acute lung injury (TRALI)
onset of acute lung injury within 6 hours of transfusion
transfusion of donor plasma containing white cells leads to agglutination and sequestration of recipient neutrophils in the pulmonary vasculature
- Requires donor antibody to recognise HLA/ neutrophil ‘specific agent’ in recipient
Major mortality and morbidity associated with transfusion
blood services developing strategies to reduce risk
- use of male only FFP
- screening platelet pheresis donors for HLA antibodies
Post transfusion purpura
Body produces alloantibodies to the introduced platelets antigens.
Alloantibodies destroy patients platelets –> thrombocytopenia usually 7-10 days post transfusion
potentially fatal
Rare, usually in women who have had multiple pregnancies or in people who have had a previous transfusion
Usually in individuals who lack HPA-1a antigen patients develop antibodies to HP-1a antigen –> platelet destruction (or HPA-5b)
Possible explanation: recipients platelets acquire phenotype of donors platelets, by binding of soluble antigens
Treatment: IVIG therapy or plasmapheresis
Reactions to plasma proteins
- Anaphylaxis
- rare
- early onset, severe reaction
- hypotension, dysphoria, abdominal cramps
- Classically occurs in IgA deficient individual who has anti IgA antibodies, –> give washed red cells and plasma - Urticarial
- common
- Slow transfusion and admin anti histamine
