Blood transfusion

Question 1

Why transfuse?

Answer 1

○ Mainly because of bleeding

○ But also failure of production

Question 2

Why are there different blood groups?

Answer 2

○ Arise from antigens
- =something that provokes an immune response
○ Red cell antigens are expressed on cell surface (proteins, sugars, lipids)
○ Can provoke antibodies

Question 3

Explain ABO blood group antigens

Answer 3

• 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

Question 4

What are the antibodies each blood group have?

Answer 4

○ 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

Question 5

What happens with fresh frozen plazma?

Answer 5

The reverse is true for FFP as it is the antibodies

Question 6

What is Anti-RhD?

Answer 6

• 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

Question 7

What is looked for in blood donors?

Answer 7

○ 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…

Question 8

What are the indications for red cell transfusion?

Answer 8

1. To correct severe acute anaemia, which might otherwise cause organ damage (patients who are bleeding out)
2. To improve quality of life in patient with otherwise uncorrectable anaemia
3. To prepare a patient for surgery or speed up recovery (frowned upon now)
4. To reverse damage caused by patient’s own red cells
   □ Sickle Cell Disease

Question 9

What should be considered when transfering red blood cells?

Answer 9

• Stored at 4°C
• Transfuse over 2-4 hours
• 1 unit increments ~5 g/L

Question 10

What should be considered when transfereing platelets?

Answer 10

• 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

Question 11

What are the indications for transfereing platelets?

Answer 11

□ 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

Question 12

How should fresh frozen plazma be transfered?

Answer 12

• 1 unit from 1 unit of blood

- Stored frozen, allow 30 minutes to thaw

Question 13

What are the indications to transfer fresh frozen plazma?

Answer 13

□ massive haemorrhage (use in 1:1 ratio?)
□ DIC with bleeding
□ ‘prophylactic’

Question 14

What are the lab tests used when transfering Fresh frozen plasma?

Answer 14

• PT (prothrombin time)

- APTT (activated partial thromboplastin time)

Question 15

How should cryoprecipitate be transfered?

Answer 15

• 1-2 pools if fib <1.0g/dl (1.5g/dl)

- Stored frozen; allow 20 minutes to thaw

Question 16

What are the lab tests used in the transfer of cryoprecipitate?

Answer 16

Fibrinogen

Question 17

What are the indications for transfereing cryoprecipitate?

Answer 17

• Renal failure

- Liver failure

Question 18

What is Coomb’s test?

Answer 18

- 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

Question 19

What is needed in the situation of a massive haemorrhage?

Answer 19

○ 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

Question 20

What are the risks of blood transfusions?

Answer 20

• 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

Question 21

What is prion disease?

Answer 21

• Transmittable by blood transfusion from early in disease in sheep
• 4 possible cases in humans

Question 22

What steps are taken to reduce the risk of potential transmission of prion disease?

Answer 22

□ Leucodepletion 1998
□ UK plasma not used for fractionation
□ Imported FFP for all patients born after 1996

Question 23

How do you manage a reaction to the transfusion?

Answer 23

• Stop transfusion
• Check patient identity against component label
• Consider: anaphylaxis, circulatory overload (TACO), acute haemolytic transfusion reaction (AHTR), bacterial infection, lung injury (TRALI) (other…)

Question 24

What happens in haemolytic disease of foetus and newborns?

Answer 24

○ 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

Question 25

In haemolytic disease of the foestus what is most imuunogenic to the least immunogenic?

Answer 25

○ Rh D most immunogenic

• also c, K
• other Rh antigens, Jka, ABO less immunogenic
• Positive DAT at birth, anaemia, jaundice

Question 26

How do you prevent haemolytic disease of the newborn?

Answer 26

• Prevention using prophylactic anti-D
  □ Sensitising events
  □ Routine at 28/40 (pregnant women in Scotland)

Question 27

What is the treatment of Haemolytic disease of the new born?

Answer 27

• Treatment by careful monitoring
  □ Antibody titres
  □ Doppler ultrasound
  □ Intrauterine transfusions

Question 28

What are cellular therapies?

Answer 28

- Leukapheresis
□ Bone marrow harvests
□ Donor lymphocyte infusions
- ‘Other banks’
□ Bone, milk, tendons, heart valves, faecal 
□ Islet cells, mesenchymal stem cells
- Gene therapies

Question 29

What happens to the foetus in haemolytic disease of the newborn?

Answer 29

The baby gets so anaemic they develop cardiac failure and either die in utero or die at birth