L20: Practical aspects of transfusion Flashcards
Pre-transfusion testing aims
- Provide red cells that will survive normally in recipients circulation
- To avoid haemolytic reactions
Steps in ensuring safe transfusion
- Correct patient identification, blood sampling and labelling at bedside
- Determination of ABO and Rh(D) type of recipient
- Antibody screen to detect significant antibodies
- Selection of appropriate red cells for transfusion
- Final cross match or compatibility test
- Removal of selected red cell units from refrigerator
- Final identity check at bedside
3 main causes of death and major morbidity in transfusion
- Incorrect blood component transfused to patient
- Transfusion related lung injury
- Transfusion transmitted infection (mainly bacterial)
Antibody screen
Anti-human Globulin technique
- Add human red cell to IgG antibody serum and incubate
- IgG coats red cells but does not agglutinate
- Washed 4 times to remove free IgG
- Add anti-human globulin and visual agglutination occurs (cross-linking of IgG)
Group and screen
- Most samples coming to blood bank request this
- Used in surgical settings when likelihood of blood being required is low
- Antibody screen should be negative
- Serum keep in lab for 7 days (or up to 28)
- Red cells can be provided quickly when needed (in 15 mins)
Compatibility testing
Three approaches
- Full crossmatch - up to 45mins, when antibody screen is positive
- Immediate spin crossmatch - 4-10mins, to detect ABO incompatibility
- Computer crossmatching - <5mins, final ABO check
Provision of red cells in emergencies
- Effective communication essential 3 main approaches, often sequential: 1. Emergency O Rh(D) negative units 2. Group specific blood 3. Provision of fully compatible blood
Final bedside check
- Common source of error
- Should involve two people
- Check patient identity against compatibility label: full name, DOB, NHI, blood group
Monitoring of transfusion
- Major problems likely to produce early signs/symptoms
- if problem: stop transfusion, maintain line with saline and seek advice
Complications of transfusions - immunological
Early:
- Haemolytic reactions
- Febrile non-haemolytic reactions
- Transfusion related acute lung injury
- Reactions to proteins
Late:
- Delayed haemolytic reactions
- Post transfusion purpura
- Graft versus host disease
Complications of transfusions - non-immunological
- Bacterial
- Viral transmission
Acute transfusion reactions - differential diagnosis
(Difficult to differentiate on clinical grounds alone)
- Bacterial sepsis
- Immediate haemolytic transfusion reaction
- Anaphylaxis
- Circulatory overload
- Febrile non-haemolytic transfusion reactions
Bacterial sepsis
- Rare but serious complication
- Contamination of blood component with bacteria able to produce an endotoxin
- Usually yersinia entercolitis
- Sudden onset of hypotensive shock within mins of starting transfusion
- Unrecognised will likely lead to serious morbidity or death
- Bacterial contamination of red cells rare because few bacteria able to grow at 4 degrees
- Contamination of platelet components more common as bacteria will grow at 22 degrees (platelets routinely cultured to reduce risk)
Immediate haemolytic transfusion reaction
- Red cells transfused and immediately destroyed by ABs in recipient’s serum
- Rare but potentially very serious
- Usually caused by ABO incompatibility
- IgM binds to red cell antigen -> activates complement -> haemolysis -> DIC
- Main complications: renal failure or DIC
- Significant morbidity common, 10% fatal
- Usually preventable
Signs and symptoms of immediate haemolytic transfusion reaction
Symptoms:
Fever, restlessness, retrosternal or loin pain
Signs: fever, hypotension, uncontrolled bleeding
Extravascular haemolytic reaction
- IgG antibody in patient plasma directed against antigen on red cells (Rh, Kell etc)
- Complement activation does not occur/only early phase (to C3 only)
- Cells removed by macrophages in spleen
- Clinically indistinguishable from acute intravascular haemolysis
Delayed haemolytic transfusion reaction
- Usually 7-10 days post transfusion
- Hb fall associated with mild jaundice
- Caused by anamnestic antibody response
- -> sensitisation by previous pregnancy or transfusion
- -> Antibody not detectable during pre-transfusion testing
- Antibody becomes easily detectable after 5 days
- Potentially avoidable
Febrile non-haemolytic transfusion reactions (FNHTR)
- Common
- Most with platelet transfusion (also with red cell components)
- Fever >38C starts during transfusion, rigors
- Clinically indistinguishable from acute haemolytic reactions
- Uncomfortable but not serious
- Occur in response to cytokines and other biological response modifiers that accumulate in blood components during storage
- Frequency reduced with introduction of pre-storage leucodepletion
Management of FNHTR
- Stop, main line with saline
- Investigate: samples to blood bank and blood cultures to exclude sepsis
- Give paracetamol, antihistamine (evidence poor), hydrocortisone (not recommended)
Transfusion related acute lung injury (TRALI)
- Onset of lung injury within 6hrs of transf.
- On CXR see opacities throughout lung
- Donor plasma containing white cell ABs directed against host HLA ABs
- Agglutination of recipients neutrophils in pulmonary vasculature = stiff lung syndrome
- Major cause of morbidity and mortality in transfusion
- Reduce risk: use only male FFP, screen platelet pheresis donors for HLA antibodies
Transfusion associated circulatory overload
- Patient’s underlying cardiovascular function major determinant of risk for volume overload
- Often difficult to distinguish from TRALI
- Stop transfusion and give diuretics
At risk: - Compromised cardiovascular function
- Volume overload state (renal failure, congestive heart failure)
- High transfusion volumes compared to patient’s intravascular volume e.g. elderly, small children
Allergic reactions
Common and usually reactions to plasma proteins
Two types:
1. Anaphylaxis/anaphylactoid
- Rare
- Early onset severe reaction
- Hypotension, dypnoea, abdo cramps
- Usually IgG deficient with anti-IgA antibodies
2. Urticarial: common, itchy rash, slow transfusion and give anti-histamine
