Blood transfusions

Cards (56)

  • Platelets =
    • produced from whole blood donations or by apheresis
    • higher risk of bacterial transmission - stored at room temperature
  • FFP =
    • male donors only to reduce risk of TRALI
    • needs to be thawed before transfusion
    • highest rate of severe allergic reaction + TRALI
  • Cryoprecipitate=
    • obtained by slowly thawing FFP
    • enriched in fibrinogen
  • Blood groups
    • inherited character of red cell surface - detected by specific allo-antibody
    • ABO blood group antigens - oligosaccharides - anchored on glycolipid substrate
  • ABO blood group antigens = acute haemolytic transfusion reactions
    RhD blood group antigen = haemolytic disease of foetus and newborn
  • ABO system =
    A and B alleles code for transferases - modify precursor called H substrate on red cell membrane
    A and B are dominant over O
    A and B are codominant
  • ABO - antigens and antibodies
    A) A
    B) anti-B
    C) B
    D) anti-A
    E) A and B
    F) none
    G) none
    H) anti-A and anti-B
  • phenotype and genotype
    A) OO
    B) AA or AO
    C) BB or BO
    D) AB
  • Landsteiner’s law =
    When an individual lacks A or B antigen = corresponding antibody is produced in the plasma
    Naturally occurring complement fixing IgM antibodies cause haemolysis of red cells expressing specific antigen
  • ABO mismatch =
    Naturally occurring IgM antibodies to A and B antigen
    Antigen-antibody complexes = initiate complement cascade
    Fromation of membrane attack complex = intravascular haemolysis
  • Symptoms and signs of ABO mismatch =
    • heat along transfusion arm
    • back pain
    • flushing + fever
    • nausea + diarrhoea
    • tachycardia + hypotension = circulatory shock
    • thick black urine to haemoglobinuria
  • RhD antigen =
    85% of population = RhD positive
    2 alleles D and d - d is silent
  • Anti-D antibody is produced on exposure to RhD+ blood through transfusion or pregnancy.
    Can cause haemolytic disease of foetus and newborn
  • Haemolytic disease of foetus and newborn
    RhD- mother carrying RhD+ foetus
    First pregnancy = fine
    Small amount of foetal-maternal haemorrhage at time of late miscarriage or childbirth = stimulates anti-D production
    Subsequent pregnancy with RhD+ foetus = materbal anti-D antibodies cross placenta - cause of haemolysis of foetal RBCs
  • Features of haemolytic disease of foetus and newborb =
    • foetal anaemia
    • heart failure
    • hydrous foetalis
  • Prevention of haemolytic disease of foetus and newborn =
    Prophylactic anti-D given to women from first pregnancy - stop development of immune anti-D
  • ABO grouping =
    • use reagents with known antibody specificity - identify antigens present on red cell = Antisera
    • use red cells with known antigen specificity to identify antibodies present in plasma
  • ABO/D grouping =
    1. test patients red cells with anti-A + anti-B and anti-D antisera - identify antigens on red cells
    2. test patients plasma against reagent red cells of group A and group B - identify antibodies in plasma
  • Agglutination with antisera =
    Positive result
    Indicates presence of antibody
  • IAT crossmatch =
    • aggulation indicates donor cells are incompatible with patients plasma
    Uses donor red cells with patient plasma + add anti-human globulin
  • Indications for red cell transfusion =
    acute blood loss - with circulatory compromise
    symptomatic anaemia Hb < 70
    Peri-operative
  • Red cell transfusion in B12/folate deficiency = can precipitate heart failure - replace haematinics
  • Patient declines transfusion due to religious reasons =
    IV iron + erythropoietin
  • CKD treatment instead of transfusion =
    iron
    erythropoietin
  • Indications for platelet transfusion =
    Prophylaxis in patients with reversible bone marrow failure undergoing chemotherapy
    Treatment of bleeding/ before surgery in thrombocytopenic patient
    Management of massive haemorrhage
  • Standard dose of platelet transfusion = 1 pool
  • Platelet transfusions not indicated =
    Auto-immune thrombocytopenia
    TTP or HUS
    Before renal biopsy in patients with renal failure
  • Indications for FFP transfusion =
    • treatment of bleeding patient with coagulopathy
    • management of massive haemorrhage
    • transfuse early in trauma
    • plasma exchange in TTP
  • FFP not indicated for =
    • volume replacement
    • warfarin reversal
  • Cryoprecipitate indications =
    • in major haemorrhage - to keep fibrinogen levels up
    • prophylaxis in APML
    • In patients with DIC - low fibrinogen
    Standard dose = 2 pools
  • Prothrombin complex concentrate =
    Vitamin K dependent clotting factors
    Used to reverse warfarin if bleeding
  • Irradiated blood =
    • risk of graft vs host disease - transfused lymphocytes recognise recipient organs as foreign
    Indications =
    Intra uterine transfusions
    neonatal exchange transfusions
    infants who previously received IUT
    severe T cell immunodeficiency
    Hodgkin’s lymphoma
    Stem cell transplants
  • All pregnant women/inra-uterine transfusions/premature infusions of cellular products must be CMV negative.
    CMV can cause miscarriage + birth defects.
  • Two sample rule -
    • patient with no blood group needs 2 separate samples for G&S before blood products can be issued
    • needs 2 venepuncture events - taken by 2 different people
  • Rate of transfusion =
    RBCs = over 90-120 min. Completed with 4 hours.
    Platelet transfusion = over 30-60 mins
    FFP = 20-30 mins
    Cryoprecipitate = 20-30 mins
  • Major haemorrhage definition =
    Loss of one blood volume with 24 hours
    50% blood volume loss within 3 hours
    150ml per minute
    Bleeding leads to HR > 110 bpm or sBP < 90
  • Major haemorrhage packs =
    • replace clotting factors and fibrinogen FFP:RBC ratio of 1:2
    • add platelets and cryoprecipitate after 1st major haemorrhage pack
  • Haemorrhage packs
    A) 4 units RBCs
    B) 4 units FFP
    C) 4 units RBCs
    D) 4 units FFP
    E) 1 unit platelets
    F) cryoprecipiate
  • Tranexamic acid =
    Antifibrinolytic drug - inhibits plasminogen conversion to plasmin
    Not recommended in patients with GI bleed
  • Heparin reversal = protamine
    Warfarin reversal = PCC and vitamin K