Blood Transfusion Flashcards
what are the indications for red cell transfusion?
- to correct severe acute anaemia, which might otherwise cause organ damage
- to improve quality of life in patient with otherwise uncorrectable anaemia
- to prepare a patient for surgery or speed up recovery
- to reverse damage caused by patient’s own red cells e.g. Sickle Cell Disease
what are the indications for platelet transfusion?
- bone marrow failure
- massive haemorrhage
- prophylaxis for surgery
- cardiopulmonary bypass (only if bleeding)
- congenital platelet disorders
what are the indications for fresh frozen plasma transfusion?
- massive haemorrhage (aim for 1:1) ratio
- DIC with bleeding
- thrombotic thrombocytopenic purpura (TTP)
- prophylactic for procedures and deranged coagulation
what does cryoprecipitate contain and what are its indications for use?
- made by thawing fresh frozen plasma (FFP) overnight at 4-8 degrees celscius
- it contains fibrinogen, factor VIII and non Willebrand factor.
- it is generally used in patients with massive bleeding and low fibrinogen
Blood groups arise from antigens on the surface of red blood cells. What is the antigen for blood group type A?
N-acetyl-galactosamine
Blood groups arise from antigens on the surface of red blood cells. What is the antigen for blood group type B?
galactose
Blood groups arise from antigens on the surface of red blood cells. What is the antigen for blood group type O?
non-functional allele (recessive)
if blood group A, have antibodies against?
B
if blood group B, have antibodies against?
A
if blood group O, have antibodies against?
A and B
if blood group AB, have no antibodies against?
A or B
whats the danger with anti-RhD blood types?
- RhD negative individuals can make anti-D if exposed to RhD+ cells e.g. by transfusion or pregnancy
- Anti-D can cause transfusion reactions or haemolytic disease of the newborn
when do ABO antigens develop on red cells?
- 16 weeks after birth
- meaning neonates do not require blood cross-matching for transfusions
how is an allergy reaction to blood transfusion managed?
- Stop the transfusion if concerns over anaphylaxis
- If mild urticaria, can slow the transfusion and give antihistamine
- give saline
- give adrenaline (in case of anaphylaxis)
- give chlorphenamine
- give hydrocortisone
what causes an acute haemolytic transfusion reaction?
caused by giving an incompatible blood bag to patient
what causes rhesus isoimmunisation?
- Can occur when a rhesus negative mother has a baby which is rhesus positive.
- If any foetal red blood cells enter the maternal circulation, the mother will form anti-D antibodies against them.
what is the danger with subsequent pregnancies in a women with anti-D antibodies?
Maternal anti-D antibodies can cross the placenta in subsequent pregnancies and cause Rhesus haemolytic disease if the future baby is rhesus positive.
“Sensitisation” events are events which cause foetal blood to cross the placenta into the maternal circulation and thus these are indications for anti-D prophylaxis. Examples include:
Examples of sensitisation events include:
Antepartum haemorrhage
Placental abruption
Abdominal trauma
External cephalic version
Invasive uterine procedures such as amniocentesis and chorionic villus sampling
Rhesus positive blood transfusion to a rhesus negative woman
Intrauterine death, miscarriage or termination
Ectopic pregnancy
Delivery (normal, instrumental or caesarean section)
what is the management of a Rh-D negative mother?
Presence of anti-D antibodies can result in incompatibility and haemolysis in future pregnancies. To attenuate this risk, anti-D antibodies are given to patients who have experienced a sensitising event. Anti-D is also given to all non-sensitised Rhesus negative mothers at 28 weeks. Note that anti-D has no effect once sensitisation has already occurred (it is prophylactic only).
