transfusion

Question 1

what are the aims of pre-transfusing testing

Answer 1

• provide red cells that will survive normally in circulation
• avoid haemolytic reactions

Question 2

steps to ensure safe transfusion

Answer 2

• correct patient identification, blood sampling
• determining blood type of recipient
• AB screen to detect clinically significant ABs
• choosing correct red cells
• final cross-match test
• final identify check at bedside

Question 3

providing red cells in emergencies

Answer 3

emergency O Rh(D) negative units

Question 4

potential complication of transfusion

Answer 4

• immediate haemolytic transfusion reaction
• bacterial sepsis
• anaphylaxis
• circulatory overload
• febrile non-haemolytic transfusion reaction

Question 5

sign and symptoms of immediate haemolytic reaction

Answer 5

• fever, restlessness, retrosternal/loin pain

- hypotension, uncontrolled bleeding

Question 6

intravascular reactions

Answer 6

• IgM antibody binds to red cell antigen -> activates complement -> red cell rupture (haemolysis); release of thromboplastin substances –> DIC
• due to ABO incompatibility
• complications include renal failure, DIC

Question 7

extravascular reactions

Answer 7

• presence of IgG antibodies (Rh, kell)
• complement activation does not occur
• red cell destruction occurs in spleen

clinically indistinguishable from acute intravascular haemolysis

Question 8

delayed haemolytic reaction

Answer 8

“memory” AB response

• AB not present in serum at pre-transfusion testing
• red cells rapidly destroyed in 7-10 days
• AB conc becomes easily detectable after 5 days
• falling Hb associated with jaundice

Question 9

pathophysiology of febrile non-haemolytic transfusion reaction

Answer 9

fevers develop associated with rigors

• white cells in red cell transfusion
• leukocyte antibodies in host -> destruction of leukocytes
• HLA antibodies produced from exposure to white cells

Question 10

management of febrile non-haemolytic transfusion reaction

Answer 10

1. stop transfusion
2. maintain line with saline
3. investigate
   
   • take blood cultures to exclude sepsis
4. medication (paracetamol, antihistamine, hydrocortisone)

Question 11

transfusion-related acute lung injury (TRALI)

Answer 11

characterised by acute respiratory distress and non-cariogenic lung oedema (within 6 hrs)

• donor plasma containing antibodies directed against host HLA antibodies
• agglutination of white cells in pulmonary vasculature, giving “stiff lung syndrome”

Question 12

how is the risk of TRALI reduced

Answer 12

• use FFP from male donor (HLA ABs most common in pregnancy)
• screen donors for HLA ABs
• blood from people with no previous transfusions

Question 13

what are the 3 steps of pre-transfusion testing

Answer 13

1. determine ABO and Rh(D) type of recipient
2. antibody screen
3. selection of blood component