Transfusion Medicine Flashcards
What determiens blood group?
the antigens present on the surface of red cells
How are the blood natigens inherited?
in a mendelian fashion - 1 allele form mom and 1 allele from dad, but you COEXPRESS both of them
What are the two most important blood group systems?
ABO and Rh
How do you makes the A, B and H antigens for the ABO system?
- you start with a protein precursor
- add FUCOSE for the H antigen
- then add N-acetylgalactosamine to the H antigen to make A antigen
- OR you add galactose to the H antigen to make B antigen
So what antigen does pretty much everyone have? what’s the rare exception?
pretty much everyone has H antigen (except for the Bombay phenotype - they don’t even have that)
What do the genes for the ABO groups encode for?
A and B encode for the enzyme that causes the attachment of the galactose or the Nacetylgalactosamine
The O gene doesn’t really have a gene product
FOr the ABO group antigens, do you have to be exposed to something you don’t have to make antibodies, or do you make them from birth?
you do NOT have to be exposed
What is the antigen in the Rh system and how is it inherited?
the D antigen - it’s mendelian autosomal dominant, so
DD and Dd is Rh positive and dd is Rh negative
Do you have to be exposed to D antigen to make antibodies, or do you make them from birth?
This one you have to be exposed to
Why is it better that we separate blood into its components for donation now?
- it’s better to just give the patient what she needs
2. it conserves blood supply
What are the five main components whole blood can be separated to?
red cells, granulocytes, platelets, fresh frozen plasma and cryoprecipitate
What patients get whole blood?
the people with the massive traumatic bleeds
Who gets red blood cells?
People who are anemia but have normal blood volume (this is the one ost commonly given)
What are leukoreduced red blood cells and when do we use them?
It’s red cells that have been treated so there’s virtually no WBCs ot platelets - we use them on patients who hae had repeated febril transfusion reactions and in people who will b egetting lots of transfusions
How long can we keep RBCs frozen for the rare blood groups?
10 years
Who receives the granulocytes?
Only patients with severe neutropenia and sepsis (with an infection that’s unresponsive to antibiotics) - so rarely because it’s hard to obtain
Who receives platelets?
People who are bleeding DUE TO THROMBOCYTOPENIA or platelet abnormalities - NOT just because they’re bleeding
WHat’s fresh frozen plasma and who gets it?
It’s plasma that includes basically all the coagultaiton factors and complement - give to people who have bleeding due to multiple factor deficiencies
What is cryoprecipitate and who gets it?
It’s derived from fresh frozen plasma but only includes some of the clotting factors - so give to patients that have deficiencies in those factors
When do we just give albumin?
Whn the patient has low blood volume and needs volume expansion (patients in shock or with nephritic syndrome)
When do we just give IgG?
for disease prophylaxis or replacement therapy in immunodeprificy states
What are the three basic tests performed before transfusing a patient?
- typing
- antibody screening
- crossmatching
What are the two strategies for typing and why do we do both?
- Forward typeing (looking for antigen on the patient’s RBCs through DAT)
- Reverse typing (looking for antibodies in the patient’s serum)
we do both as a way to double check ourselves
What are we looking for in the antibody screen?
we’re trying to detect any antibodies other than the ABO in patient’s serum - so Rh, Kell, Duffy, Lutheran, etc.
What is cross match testing?
You do a final check to make sure the recipient and donor blood are compatible - so you just mix patient serum with the donor red cells and look for agglutination
What are the four negative reactions you can have to transfusion?
1, acute hemolytic transfusion reactions (the worst)
- delayed hemolytic transfusion reaction
- febrile non-hemolytic reaction
- allergic reaction
What happens in acute hemolytic transfusion reaction?
THe patient had IgM antibodies against the donor cells (usually a mistake in the ABO matching), which will bind complement and lyse the RBCs
symptoms are fever, chills, chest pain, hypotension, kidney pain, SOB, nausea
What will labs show in an acute hemolytic transfusion reaction?
hemolysis - so decreased haptoglobin, increased bilirubin, hemoglobinemia, hemoglobinuria
What do you do if you suspect acute transfusion reaction?
- stop the transfusion!!!
- verify the right blood was given
- maintan IV
- maintain blood pressure and ventilation
- notify blood bank
- obtain blood and urin for transfusion reaction workup
- send blood bag to bank
What happens in a delayed hemolytic transfusion reaction?
It’s hemolysis that occurs well after the transufsion- days to a week and they just don’t get the bump in Hgb you expect - often it goes down
usually from antibodies to non-ABO antigens likRh
What is a febrile non-hemolytic transfusion reaction?
It’s sudden onset fever, headache, malaise, nausea, vomiting, and chest pain caused yb antibodies in the patient reacting against the donor WNCs or platelets, releasing pyrogens
How can you avoid a febrile non-hemolytic transfusion reaction in a patient hx of such?
give leukocyte-depleted blood
WHat’s the most ocmmon acute transfusion reaction>
allergic reactions
What’s the allergic reaciton most likely to?
donor plasma proteins
What’s the symptom in alllergic reaction?
hives, but rarely anaphylaxis
What do you do with a patient that has an alergic transfusion reaction?
stop the transfusion, give an antihistamien and restart transfusion in 15-30 mintues
What is the presentation of a transfusion-related bacterial infection?
It’s a sudden (durin transfusion or up to a few hours later) onset of fever, hypotension and shock
What infectious diseases do we typically check bloo dunits for?
HIV, HTLV, hep B and C and synphilis
What happens in circulatory overload?
WHen too large a volume of blood is given too quickly - headache, SOB, CHF and hypertension
What happens in iron overload?
When the patient just has too much iron deposition- can damage heart and liver
people with repeat transfusions are at highest risk
WHat’s graft vs host disease?
It’s a rare complication caused by donor lymphocytes in the blood prouct - the donor T cells proliferate in the recipitn and recognize host HLA antigens and attack host tissues- most cases are fatal, fortunately its very rare
What do we do to blood products to hopefully avoid graft vs host?
we irradiate the blood products to prevent dono lymphocytes from proliferating
