3. Blood Transfusion Flashcards
Why do we transfuse blood?
Bleeding
Poor making of blood
How do blood groups arise?
Arise from antigens, red cell antigens are expressed on cell surfaces (proteins, sugars, lipids). Can provoke antibodies
Explain ABO phenotypes
Each red blood cell contains genes that encode for glycosyltransferas. Glycans added to proteins or lipids on red cells. These mark the cells as a specific category e.g. A antibodies. They reject any other cell that does not reproduce the same category.
How do each blood groups distinguish between groups?
Blood group A has antibodies against B
Blood group B has antibodies against A
Blood group O has antibodies against A and B
Blood group AB has no antibodies
This is not the case for FFP donors. AB can donate to all where O can only donate to O
What happens if someone is given the wrong blood?
IgG binds to red blood cells more readily and will simply coat the blood cell so it is destroyed by the spleen. However if the IgM comes into contact with the blood it starts another pathway that leads to:
Blood clotting may occur throughout your body, shutting off the blood supply to vital organs or causing a stroke. Too much blood clotting can use up clotting factors and leave you at risk of excessive bleeding. Some of the products released from broken-down blood cells can cause kidney damage and possibly kidney failure.
What is the rhesus antigen?
Rhesus (RhD). Caused by the RHD and RHCE genes
What is anti-RHD?
RhD negative individuals make anti D if exposed to RhD positive cells.
This can lead to transfusion reactions or haemolytic disease of the newborn
How is blood taken?
Skin extensively cleaned, diversion pouch is used to take blood and then separates the blood into red, plasma and white cells.
What are the indications for red cell transfusions?
Correct severe acute anaemia, which might otherwise cause organ damage
To improve quality of like in patients with otherwise uncorectable anaemia
To prepare a patient for surgery or to speed up recovery
To reverse damage caused by a patients own red cells. Sickle cell disease
How are red blood cells stored and transfused
I unit is 440ml, transfuse over 2-4 hours, stored at 4 degrees
How do you quantify platelets?
1 dose platelets= 4 pooled or 1 apheresis donor.
Stored at 22 degrees, shelf life 7 days,
Transfuse over 20-30 minutes
You can Bypass groups as all platelets are screened for AB and Rhesus factors.
When would you need platelets?
Massive heamorrhage- keep platelet count above 75x109/l
Bone marrow failure-
Prophylaxis for surgery
Cardiopulmonary bypass- use only if bleeding
How do yiu quantify plasma?
1 unit from 1 unit of blood
Stored frozen, allow 30 mins to thaw
What are the indications for needing plasma components?
Massive heamorrhage
DIC with bleeding
Prophylactic
How do you deal with preventing blood mismatches
Make junior doctors take blood by the bedside and put the name on it there and then
Have two samples that concur to make sure it matches
Stop people just taking up blood and chucking it in
