Blood transfusion Flashcards
Why transfuse?
○ Mainly because of bleeding
○ But also failure of production
Why are there different blood groups?
○ Arise from antigens
- =something that provokes an immune response
○ Red cell antigens are expressed on cell surface (proteins, sugars, lipids)
○ Can provoke antibodies
Explain ABO blood group antigens
- ABO gene encodes glycosyltransferase
- Glycans added to proteins or lipids on Red Cells
- A and B genes code for transferase enzymes
- A antigen is N-acetyl-galactosamine
- B antigen is galactose
- ‘O’ gene is non-functional allele
- So A and B are (co-)dominant and O is recessive
What are the antibodies each blood group have?
○ Blood group A, has antibodies against B
○ Blood group B, has antibodies against A
○ Blood group O, has antibodies against A and B
○ Blood group AB, has no antibodies against A and B
What happens with fresh frozen plazma?
The reverse is true for FFP as it is the antibodies
What is Anti-RhD?
- RhD negative individuals can make anti-D if exposed to RhD+ cells
□ Transfusion or pregnancy - Anti-D can cause transfusion reactions or haemolytic disease of the new-born
What is looked for in blood donors?
○ Extensive ‘behavioural’ screening ○ Sex, age, travel, tattoos………… ○ Tested for ABO and Rh blood groups ○ Screened for HepB/C/E, HIV, syphilis ○ Variably screened for: - HTLV1, malaria, West Nile virus, Zika virus…
What are the indications for red cell transfusion?
- To correct severe acute anaemia, which might otherwise cause organ damage (patients who are bleeding out)
- To improve quality of life in patient with otherwise uncorrectable anaemia
- To prepare a patient for surgery or speed up recovery (frowned upon now)
- To reverse damage caused by patient’s own red cells
□ Sickle Cell Disease
What should be considered when transfering red blood cells?
- Stored at 4°C
- Transfuse over 2-4 hours
- 1 unit increments ~5 g/L
What should be considered when transfereing platelets?
- 1 dose platelets (=4 pooled or 1 apheresis donor)
□ increments 20-40.109/L - Stored at ~22oC, shelf life 7 days
- Transfuse over 20-30 minutes
What are the indications for transfereing platelets?
□ Massive haemorrhage ® Keep platelet count above 75x109/l □ Bone marrow failure ® platelet count <10-15 × 109/litre ® or <20 × 109/litre if additional risk, e.g. sepsis □ Prophylaxis for surgery ® Minor procedures 50x109/l; ® More major surgery 80x109/l; CNS or eye surgery 100x109/l □ Cardiopulmonary bypass ® use only if bleeding
How should fresh frozen plazma be transfered?
- 1 unit from 1 unit of blood
- Stored frozen, allow 30 minutes to thaw
What are the indications to transfer fresh frozen plazma?
□ massive haemorrhage (use in 1:1 ratio?)
□ DIC with bleeding
□ ‘prophylactic’
What are the lab tests used when transfering Fresh frozen plasma?
- PT (prothrombin time)
- APTT (activated partial thromboplastin time)
How should cryoprecipitate be transfered?
- 1-2 pools if fib <1.0g/dl (1.5g/dl)
- Stored frozen; allow 20 minutes to thaw
What are the lab tests used in the transfer of cryoprecipitate?
Fibrinogen
What are the indications for transfereing cryoprecipitate?
- Renal failure
- Liver failure
What is Coomb’s test?
- Anti-human immunoglobulin □ If they clump together then it is a positive Coon's test - Direct □ autoimmune haemolytic anaemia □ passive anti-D □ haemolytic transfusion reactions - Indirect □ Cross matching
What is needed in the situation of a massive haemorrhage?
○ Good communication between all teams essential ○ Definitive management - Rapid Control of bleeding □ Obstetric intervention, surgery, interventional radiology ○ Immediate supply of: - 6 units red cells - 4 units FFP (cryoprecipitate?) - 1 unit platelets
What are the risks of blood transfusions?
- Never events: death or harm (transfusion of ABO incompatible component)
- Transfusion associated circulation overload (TACO): too much blood too quickly
- Transfusion associated lung infection (TRALI)
□ Transfused anti-leucocyte Abs in donor plasma interact with patient’s WBC
□ Bilateral pulmonary infiltrate
□ Supportive management, ventilation - Acute transfusion reaction (ATR)
- Febrile
- Allergic
- vCJD risk
What is prion disease?
- Transmittable by blood transfusion from early in disease in sheep
- 4 possible cases in humans
What steps are taken to reduce the risk of potential transmission of prion disease?
□ Leucodepletion 1998
□ UK plasma not used for fractionation
□ Imported FFP for all patients born after 1996
How do you manage a reaction to the transfusion?
- Stop transfusion
- Check patient identity against component label
- Consider: anaphylaxis, circulatory overload (TACO), acute haemolytic transfusion reaction (AHTR), bacterial infection, lung injury (TRALI) (other…)
What happens in haemolytic disease of foetus and newborns?
○ Mother has negative RhD blood cells but foetus has positive
○ The mother’s antibodies senses the negative RhD cells and then destroys them
○ IgG crosses the placenta and then destroys the foetus’ positive RhD blood cells
In haemolytic disease of the foestus what is most imuunogenic to the least immunogenic?
○ Rh D most immunogenic
- also c, K
- other Rh antigens, Jka, ABO less immunogenic
- Positive DAT at birth, anaemia, jaundice
How do you prevent haemolytic disease of the newborn?
- Prevention using prophylactic anti-D
□ Sensitising events
□ Routine at 28/40 (pregnant women in Scotland)
What is the treatment of Haemolytic disease of the new born?
- Treatment by careful monitoring
□ Antibody titres
□ Doppler ultrasound
□ Intrauterine transfusions
What are cellular therapies?
- Leukapheresis □ Bone marrow harvests □ Donor lymphocyte infusions - ‘Other banks’ □ Bone, milk, tendons, heart valves, faecal □ Islet cells, mesenchymal stem cells - Gene therapies
What happens to the foetus in haemolytic disease of the newborn?
The baby gets so anaemic they develop cardiac failure and either die in utero or die at birth
