Lecture 20: Transfusions

Question 1

(Aim of) Pre-transfusing testing?

Answer 1

• Provide red cells for transfusion that will survive normally in the recipients circulation
• To avoid haemolytic transfusion reactions
• Correct patient identification and labelling
• Determination of the ABO, Rh(D) type + antibody screen -(a known patient is checked against the records, an unknown is checked twice)
• A final cross match test

Question 2

What is the best type of blood to give in an emergency when they are more likely to die of lack of blood than imcompatability?

Answer 2

Group O Rh(D) negative

then move to Group ABO specific blood

and by this time specific matched blood should be ready

Question 3

Acute transfusion reactions?

Answer 3

Occur early after giving transfusion and if problems develop then: stop transfusion-maintain line with saline -seek advice

Differential diagnosis:

• bacterial sepsis (rare, endotoxin from bacteria, rapid hypotensive shock)
• Immedaite heamolytic transfusion reaction (rare, usually from ABO incompatability, renal failure and disseminated intravascular coagulation - fever, restless, loin pain)
• anaphylaxis (slow the transfusion and give antihistamines for allergic reaction but for severe anaphylaxis is rare and prevents with hypotension, dyspnoea and abd cramps)
• circulatory overload (HF from increased BV - transfuse slowly and if needed give diuretics)
• febrile non-haemolytic transfusion reaction (Relatively common, occur mostly in platelet transfusion, fever and rigors, have been reduced due to removal of WBC from blood products)

Question 4

Delayed Haemolytic transfusion reactions?

Answer 4

Classically occurs 7-10 days post transfusion as their Hb falls and is associated with jaundice

Caused by amamnestic antibody response - sensitisation by previous transfusion or pregnancy. Antibody not detectable during pre-testing but B-cells for producing this antibody still exist.

Potentially avoidable if they have previously been tested and found to have an antibody present in their blood.

Question 5

Transfusion related acute lung injury?

Answer 5

Within 6 hours of transfusion - donor plasma containing WBC antibodies leads to agglutination and sequestration of recipient neutrophils in the pulmonary vasculature.

Recognised to a major cause of morbidity and mortality associated with transfusion (hence only using males for FFP)