Blood transfusion

Question 1

What are the major blood groups?

Answer 1

A - common H stem + A antigen + anti-B antibodies
B - common H + B antigen + anti-A antibodies
O - only common H stem, anti-A antibodies, anti-B antibodies
AB - common H + A and B antigen + no antibodies

Question 2

Explain the clinical importance of blood groups

Answer 2

Each person has naturally occurring IgM ABs against any antigen that is not present on own red cells

Complete antibody - fully activates complement cascade to cause haemolysis of red cells

If patient receives an ABO incompatible transfusion then AB/An interaction is often FATAL

Cytokine storm, lysis, CV collapse –> DEATH

Should always give crossmatched blood to prevent this

Question 3

How are blood donors screened?

Answer 3

1. To keep blood safe for patient:
   - Test for infections (not failsafe): Hep B, Hep C, HIV, HTLV, syphilis, CMV
   - Questioning for risk behaviour
2. To keep donation safe for donors:
   - Exclude risky ones, e.g. people w/heart problems

Question 4

What blood components are used clinically?

Answer 4

Red cells
Platelets
Plasma - fresh frozen and cryoprecipitate, plasma for fractionation (not UK)

Question 5

What are the potential side effects of blood and plasma transfusions?

Answer 5

1. Severe acute transfusion reactions:
   a) Allergic reaction: urticaria, oedema, dizziness, headaches, fever, SOB, chills, shivering, swelling of lips/eyelids
   b) Anaphylaxis: severe SOB, faintness, clammy, rash/swelling of lips/eyelids
   c) Transfusion-related acute lung injury (TRALI)
   d) Haemolytic transfusion reaction (HTR): hypo/ertension, pain (along IV infusion line, chest or back), acute resp distress, dark urine, urticaria, fever, chills, bleeding, oozing (DIC)
   e) Fluid overload: heart failure, fluid on lungs, SOB
2. Bacterially contaminated blood: can lead to sepsis
   Virally contaminated blood
3. CV collapse
4. Death

Question 6

When do you use a blood transfusion?

Answer 6

Must balance benefits vs risks
Only when no safer alternative available
E.g. massive bleeding when plain fluids insufficient; anaemia if iron/folate/B12 inappropriate