B Lectures 7 & 8: Blood Transfusion 1+2 Flashcards
Recall 2 ways in which patients’ blood group is tested
- Using anti-A,B and O reagents against the patient’s red blood cells2. Also use ‘reverse group’ - known A and B group RBCs against the patient’s plasma
Describe the process of antibody testing of blood
Group and screen- Use 2 or 3 reagent red blood cells containing all the important RBC antigens between them- Then incubate the patient’s plasma using the indirect antiglobulin technique
What is the purpose of ‘immediate spin’ blood testing?
Used in emergencies onlyIncubation for just 5 minutesDetermines ABO compatibility only
What are the 3 pillars of patient blood management?
- Optomise haematopoiesis2. Reduce bleeding (eg stop anti-platelt drugs, cell-salvage techniques) 3. Harness and optomise physiological tolerance of anaemia
For which blood products is D compatibility required?
Red cells and platelets (but not FFP or cryoprecipitate)
What is the storage temperature of red cells, platelets, FFP and cryoprecipitate?
Red cells: 4 degrees CPlatelets: 20 degrees CFFP: 4 degrees C once thawedCryoprecipitate: Room temp once thawed
What is the storage length of red cells, platelets, FFP and cryoprecipitate?
Red cells: 35 days Platelets: 7 daysFFP: 24 hoursCryoprecipitate: 4 hours
What is the transfusion rate of red cells, platelets, FFP and cryoprecipitate?
Red cells: 1 unit over 2-3 hoursPlatelets: 1 unit over 20-30 minsFFP: 1 unit over 20-30 minsCryoprecipitate: 1 unit over 20-30 mins
How much blood loss counts as ‘major’?
> 30% blood volume lost
When are platelets contra-indicated?
TTP/ heparin-induced TTP
How low does haemaglobin need to be to require transfusion peri-operatively vs post-chemo?
Peri-op/ crit care: <70g/dLPost-chemo: <80g/dL
In what type of surgery is post-operative cell salvage most often done?
Knee surgery
What are the steps of intra-operative cell salvage?
Centrifuge, filter, wash and re-infuse blood
What special blood reuquirements do pregnant women have?
CMV neg
What special blood reuquirements do highly immunocompromised patients have?
Blood needs to be irradiated
What special blood requirements do patients who have had severe reactions in the past to transfusion have?
Washed cells
Recall the 10 classes of transfusion reaction, and which are acute/ delayed?
Acute (<24 hours): 1. Acute haemolytic (ABO incompatible) 2. Allergic/ anaphylaxis3. Bacterial infection 4. Febrile non-haemolytic 5. TACO/TRALIDelayed: 6. Delayed haemolytic transfusion reaction (antibodies) 7. Transfusion-associated GVHD8. Infection (malaria, CJD) 9. Post-transfusion purpura10. Iron overload (thalasaemia patients mostly)
What monitoring should be done during a blood transfusion as minimum?
- Baseline temp, HR, RR, BP2. Repeat obs after 15 mins3. Repeat hourly after end of transfusion
What are the features of febrile non-haemolytic transfusion reaction?
Temp increase >1%Chills and rigors
Why is febrile non-haemolytic transfusion reaction rare nowadays?
Blood is now leucodepleted to reduce risk of febrile non-haemolytic transfusion reaction
How should febrile non-haemolytic transfusion reaction be managed?
Stop/ slow the transfusion and give paracetamol
What is the pathophysiology of febrile non-haemolytic transfusion reaction?
Cytokines released by white blood cells during storage cause a febrile reaction upon transfusion
What should be the management of an allergic transfusion reaction?
Stop/ slow transfusionIV antihitamines
What are the symptoms of ABO incompatibility?
Shock and feverRestlessness, fever, vomiting and collapse
What is the appropriate management for ABO incompatibility?
Stop transfusionCheck patient and componentRepeat cross match and DAT
What are the symptoms of bacterial contamination of blood?
Presents very similar to wrong blood - shock, increased temp, restless, fever, vomiting, collapse
How does bacterial contamination of blood cause symptoms?
Bacterial growth –> endotoxin which causes immediate collapse
Recall some protocols for prevention of bacterial contamination of blood
Donor questionning Arm cleaningDiversion of first 20mls of bloodProper storage
Which patients are at most risk of anaphylactic reaction to a blood transfusion?
Those with IgA deficiency
How quickly does TACO/TRALI present?
Within 6 hours
What does TACO stand for?
Transfusion-associated circulatory overload
What are the symptons of TACO?
SOB, decreased SaO2, increased HR and BP (due to pulmonary oedema)
What should be checked pre-transfusion to reduce the risk of TACO?
Check the patient is not always in positive fluid balanceCheck they don’t have risk factors for TACO - if they do, they need a aprophylactic diuretic
What is the probably cause of TRALI?
Antibodies
What is the main difference in the management of TACO and TRALI?
TRALI doesn’t repsond to furosemide
What is the pathophysiology of delayed haemolytic transfusion reaction?
Development of an ‘immune’ antibody to a RBC antigen they lack (‘allo-immunisation’)
Over what time period does delayed haemolytic transfusion reaction develop?
5-10 days
Recall 2 clinical features of delayed haemolytic transfusion reaction
DAT positiveJaundiced
What is the prognosis of transfusion-associated GVHD?
Always fatal
Which patients are most at risk of transfusion-associated GVHD?
Severely immunosuppressed
What is the cause of transfusion-associated GVHD?
Failure to destroy donor lymphocytes completely
How can transfusion-associated GVHD be prevented?
Irradiate blood for immunosuppressed patients
What are the symptoms of transfusion-associated GVHD?
Severe diarrhoeaLiver failureSkin desquamationBone marrow failure
How long after a transfusion do post-transfusion purpura present?
7-10 days
How should post-transfusion purpura be treated?
IV Ig
What is the main complication risk of post-transfusion purpura?
Big bleeding
How can iron overload be prevented?
Chelation (Exjade)
When are pregnant women checked for RBC Immunoglobins during pregnancy, to prevent GVHD?
12 and 28w gestation
If a pregnant woman has RBC antibodies that put the baby at risk of GVHD, what should be done?
- Check if Father has the antibodies (were they inherited?) 2. Monitor Ig level3. Check ffDNA sample4. Monitor foetus for anaemia5. Deliver baby early
What is the anti-D dosing during pregnancy?
Before 20w, 250iuAfter 20w, minimum 500iu
How does anti-D work during pregnancy to prevent GVHD?
RhD pos foetal cells get covered in anti-D IgMother’s reticulo-endothelial system removes coated cells (spleen) before they get chance to sensitise mother
How quickly must anti-D be given following sensitisation events?
Within 72 hours
Recall some examples of sensitising events
Spontaneous miscarriagesAmniocentesis/ CVSAbdominal traumaExternal cephalic versionStill birth
What is the routine anti-D prophylaxis for mother’s with no obvious sensitising events?
1500iu anti-D at 28-30w gestation
