Haematology 14 - Blood Transfusion 1 & 2 Flashcards
What is the importance of RhD negative RBC?
What happens if you give RhD+ blood to RhD- people?
These are safe to give to everyone but are often in short supply
If you give RhD+ blood to RhD- patients doesn’t cause an acute disaster but can induce the formation of anti-D antibodies
Next time person is transfused it must be with RhD- blood because if you give Rhd+ blood again it will cause haemolytic disease
What does a group and screen consist of?
Group: blood group testing using forward and reverse group- Test patient’s ABO and RhD group
Screen: screening the patient’s plasma for potential antibodies against RBC that will be transfused
Recall 2 ways in which patients’ blood group is tested
- Forward group (to figure out which antigens are on patient’s RBC): Using anti-A,B, D and O reagents against the patient’s red blood cells
- Also use ‘reverse group’ - known A and B group RBCs against the patient’s plasma. If patient is positive for anti-A, it means they are B-positive (hence “reverse”).
Describe the process of antibody testing of blood
- 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
*if there are visible agglutination/clumps forming then antibodies are present in patient’s plasma
What are the two types of cross match?
1) Electronic cross-match:
Compatibility determined by IT system rather than manually. Done in emergency situations
2) Serological cross match (see picture)
a) Full cross match - uses IAT
b) immediate spin - quicker technique - used in emergencies
What is the purpose of ‘immediate spin’ blood testing?
Used in emergencies only
Incubation for just 5 minutes
Determines ABO compatibility only
What are the 3 pillars of patient blood management?
- Optomise haematopoiesis- treatment of anaemia
- Reduce bleeding (eg stop anti-platelt drugs, cell-salvage techniques)
- Harness and optomise physiological tolerance of anaemia
For which blood products is D compatibility required?
Red cells and platelets (but not FFP or cryoprecipitate)
*for all they need to be ABO compatible
*also for FFP and crypprecipiatte you don’t need to do cross match
Who is the universal donor for platelet transfusions?
Group A!!
Not group O like for RBC!
What is the storage temperature of red cells, platelets, FFP and cryoprecipitate?
Red cells: 4 degrees C (fridge)
Platelets: 20 degrees C (room temperature) >>> more likely to be contaminated
FFP: 4 degrees C once thawed
Cryoprecipitate: Room temp once thawed
Red cells and FFP: fridge
Platelets and cryoprecipitate: room temperature
What is the storage length of red cells, platelets, FFP and cryoprecipitate?
Red cells: 35 days
Platelets: 7 days
FFP: 24 hours
Cryoprecipitate: 4 hours
What is the transfusion rate of red cells, platelets, FFP and cryoprecipitate?
Red cells: 1 unit over 2-3 hours
Platelets: 1 unit over 20-30 mins
FFP: 1 unit over 20-30 mins
Cryoprecipitate: 1 unit over 20-30 mins
What is the trigger for transfusion in these situations?
1) major blood loss: >30% blood volume lost
2) peri-operative: Hb<70 or 80 depending on comorbidities
3) post chemo: hb <80
**also consider symptomatic anaemia- IHD, breathless, ECG changes
How much does 1 unit of RBC transfusion equate to in g/L in the average 70.80 kg man?
1 unit = 10g/L
How much blood loss counts as ‘major’?
>30% blood volume lost
When are platelets contra-indicated?
-
Thrombotic thrombocytopaenic purpura (TTP)
- unfractionated heparin rather than LWMH
-
Heparin-induced thrombocytopaenia and thrombosis (HiTT)
- Platelets block up the microcirculation so giving platelets will aggravate this
Giving platelets gives the condition worse
What are the indications for FFP transfusion?
1) Massive transfusion
2) Liver disease - only if PT<1.5
3) Single coagulation factor deficiencies eg factor V
4) TTP - to replace ADAMS enzyme (special type of FFP)
5) DIC in the presence of bleeding and other abnormal features
: all the coagulation factors and platelets are removed from the cell intaoperative/post operative cell salvage blood so need to give FFP
What does cryoprecipitate contain?
In which situations can you get your own blood?
Intraoperative or perioperative cell salvage
but NOT for pre-operative autologous deposit as no net benefit- also not done in the UL
: all the coagulation factors and platelets are removed from the intraopeative and post operative cell salvage blood so need to give FFP
Cell salvage is useful in people with RARE blood groups and Jehovah’s witnesses
In what type of surgery is post-operative cell salvage most often done?
Knee surgery
- Collect blood that is lost post-operatively into a wound drain
- Mainly done for orthopaedic operations (e.g. knee surgery)
What are the steps of intra-operative cell salvage?
Centrifuge, filter, wash before re-infusing blood
*ie collect blood lost during operation and give it back to pt
What special blood reuquirements do pregnant women have?
CMV neg
What special blood reuquirements do highly immunocompromised patients have?
patients cannot destroy incoming donor lymphocytes
Blood needs to be irradiated in order to avoid fatal transfusion associated graft v s host disease
**irradiation is different to leukodepletion (blood is leukodepleted by default)
What special blood requirements do patients who have had severe allergic reactions in the past to transfusion have?
Washed cells (RBC and platelets)
also seen in IgA deficient patients
Recall the 10 classes of transfusion reaction, and which are acute/ delayed?
Acute (<24 hours):
- Acute haemolytic (ABO incompatible)
- Allergic/ anaphylaxis
- Bacterial infection >> occurs typically with platelets
- Febrile non-haemolytic
- TACO/TRALI (TRALI is more rare than TACO)
- TACO common in patients with pre-existing cardiorespiratory conditions >> so may already be fluid overloaded
- these patients should have prophylactic diuretics
- main distinguished between TRALI and TACO = BP
Delayed (>24h):
6. Delayed haemolytic transfusion reaction (antibodies) = 7-10 days after
- anaemia + dark urine + jaundice
- Transfusion-associated GVHD: 2 weeks post-transfusion
- Infection (viral, malaria, CJD)
- Post-transfusion purpura
- Iron overload (thalasaemia patients mostly)
What monitoring should be done during a blood transfusion as minimum?
- Baseline temp, HR, RR, BP BEFORE TRANSFUSION
- Repeat obs after every 15 mins - most reactions start within 15 mins
- Repeat hourly after end of transfusion- some reactions start after end of transfusion
Many acute reactions start as:
- Rise in temperature or pulse
- Fall in BP
- This can occur before the patient feels symptoms
What are the features of febrile non-haemolytic transfusion reaction? + cause
WHat severity is this?
Temp increase <1 degree - Low fever
Chills and rigors
*NO CIRCULATORY COLLAPSE*
*caused by release of cytokines in donor which cause a reaction*
*in a qs- might be someone who feels v feverish but when you go to measure the temp it’s not that high*
*mild-moderate severity
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
Allergic transfusion reactions:
- Sx
- Management:
- Cause. +risk factors (2)
Severity: mild/moderate
Sx: : urticarial rash, wheeze,
Management:
- Stop/ slow transfusion
- IV antihitamines
Cause:
- allergy to plasma protein (more common with plasma than blood products) so may not recur if they receive diff product
- more common if other allergies/atopy present
What are the symptoms of ABO incompatibility?
- May occur 1-2 hours post-transfusion
acute intravascular haemolysis (IgM-mediated)
- Shock:Low BP and high HR (shock)
- high grade fever- unlike febrile non haemolytic transfusion reaction
- Restlessness, vomiting and collapse
- Flushing
**also this is the only transfusion reaction that is associated with pain - particualrly in abdomen, chest, loin or back
**NB does not present with breathlessness**- this is seen in anaphylaxis reactoin
What is the appropriate management for ABO incompatibility?
how can it be prevented
Stop transfusion
Check patient and component
Repeat bloods:
- FBC
- Biochemistry
- Coagulation
- Repeat crossmatch
- Direct antiglobulin test (DAT)>>> would be POSITIVE
Contact senior haemoatologists
prevention:
- adequate of bedside check
- correctly labelled and handwritten blood sample
- avoid Laboratory error
What are the symptoms of bacterial contamination of blood?
Presents very similar to wrong blood (ABO mismatch) - shock, increased temp, restless, fever, vomiting, collapse
How does bacterial contamination of blood cause symptoms? and which products have highest risk of contamination
Bacterial growth –> endotoxin which causes immediate collapse
bacteria could have come from the donor
bacteria could have been introduced during processing
order of liklihood in products:
- Platelets (stored at room temperature)
- RBCs
- FFP
Recall some protocols for prevention of bacterial contamination of blood
Donor questionning
Arm cleaning
Diversion of first 20mls of blood for testing
Proper storage
With ALL components, look for abnormalities such as clumps of discoloured debris, brown plasma etc.
RBCs:
- Store in a controlled fridge at 4oC (+/- 2oC)
- Shelf life: 35 days
- If it is kept out for 30 minutes, it needs to go back in the fridge for 6 hours. This is to help reduce the risk of bacteria growing.
- Complete transfusions should take place within 4.5 hours of leaving the fridge
Platelets:
- Stored at 22oC- Room temperature (+/- 2oC)
- Shelf life: 7 days (if had bacterial testing (BacT), otherwise 5 days)
- Screened for bacteria before release
- Transfuse across 20 minutes
Presentation of anaphylaxtic reaction + mechanism of action
mechanism of action: IgE antibodies in the patient cause mast cell degranulation and release of vasoactive substances
presentation
- soon after the start of transfusion
- Very similar to ABO incompatibility
- shock + collapse + hypotension + tachycarida
- Often laryngeal and/or facial oedema
- wheeze + breathlessness (this is what differentiates this from ABO incompatibility)
Which patients are at most risk of anaphylactic reaction to a blood transfusion?
Those with IgA deficiency - tend to have more severe reaactions
anti-IgA antibodies develop in response to exposure to IgA in the donor blood (transfusion especially with plasma)