Transfusion Medicine - Krafts Flashcards
What determines a blood group?
Antigens on the red cell surface!
Red Cell antigens
- Antigens are inherited from parents
- REALLY important for transfusion
- ABO and Rh systems
ABO system
A, B, AB, or O
- A has A antigens
- Type O= neither A or B antigens
** what you don’t have, you make antibodies to.
How do make an antigen?
- Start with protein precursor
- Add fucose to make H antigen
- Add N-acetylgalactosamine to H Ag –> A Ag
- Add galactose to H Ag –> B Ag
H Gene
Everybody has this
Codes for an enzyme that makes H antigen
A, B, and O genes:
- you have 2 genes
- 6 possible genotypes: AA, BB, AB, AO, BO, OO
- A and B code for enzymes that make A and B antigens
- O has no gene product
Whats the big deal with blood types?
- We make antibodies to the antigens we DON’T have!!
- Anti-A antibodies lyse type A RBCs.
- Anti-B antibodies lyse type B RBCs
Universal Recipient?
AB! Yay, no antibodies made – bring on any blood type for transfusion.
Universal dOnor?
Type O
Type O can only get Type O blood.
But WAIT, give type O to an A, the type O has anti A antibodies –Doesn’t that suck?
Nope, doesn’t matter :)
- -Not many antibodies in a packed unit of RBCs
- only concerned about the antibodies that the recipient has.
Rh System:
What are the antigens?
D antigen! (=Rh factor)
Alleles: D and d
DD ==Rh+
Dd=Rh+
dd= Rh - (that’s me :] )
Rh System: antibodies
These are acquired. You have to be exposed to the D antigen first.
Lack the D antigen +++ Get exposed to D + blood ==== make anti-D
-comes into play in pregnancy: give Rhogam if you have Rh- mom with Rh+ baby
Other Systems:
- antibodies to antigens are acquired
- Only come into play if you have lots of transfusion or pregnancies.
- These aren’t included in routine tests
Blood Transfusion: blood products
Whole blood, red cells, platelets, granulocytes, cryoprecipitates, fresh frozen plasma
Apheresis donation
Take platelets or neutrophils and then return blood to the donor.
Indications for WHOLE BLOOD transfusion
RBC, WBC, platelets, plasma
Massive Hemorrhage
Indications for Red cell transfusion
RBC, and a little WBC, platelets, and plasma
Low hemoglobin
Leukocyte-Reduced Red cell transfusion?
RBC, NO WBC, rare platelets, a little plasma
Decreased alloimmunization
Decreased allergic reaction
(patient is reacting to WBCs)
Frozen Red Cell transfusion indications?
RBC, a few WBC
Storage of rare blood types
Granulocyte transfusion indications?
neutrophils
Sepsis in neutropenic patients
-sometimes BMT patients or hard hitting chemo pts .
Platelet transfusion indications?
Bleeding due to thrombocytopenia
Fresh Frozen Plasma indications?
Plasma- including all coagulation factors
-Bleeding due to multiple factor deficiencies (DIC)
Cryoprecipitates indications?
(fibrinogen, von Willebrand factor, VIII, XIII) –don’t need to know all that is in this
Low fibrinogen, vW disease, hemophilia A, XIII deficiency
VIII indications?
Hemophilia A
IX indications?
Hemophilia B
Albumin indications?
Hypovolemia with hypoproteinemia
IvIG indications?
intravenous
disease prophylaxis
autoimmune disease
Immune deficiency states
Testing – Forward Type:
Look to see what antigens are on red cells:
1. Take pt’s red cells
2. + anti A antibodies
3 +anti human globulin (AHG)
Clumping === A antibodies coating red cells and red cells HAVE A antigens
No clumping == no A antigens
*Do this with Anti B Antibodies too!
Reverse Typing:
*to double check your work
Looking for antibodies in serum
- take pt’s serum
- reagent red cells Type B
- AHG
clumping == pt has anti B antibodies
No clumping == pt does not have anti B antibodies –> they have Type B or AB blood.
Crossmatch Test:
do this when you know you are putting red cells into patient.
Patient serum + donor RBC + AHG —->
If you get clumping DON’T put donor blood in patient.
*last double check
Antibody Screen:
- look for antibodies against weird blood group systems.
- do if pt has has had multiple pregnancies/transfusions and they are starting to have transfusion rxns.
agglutination == + test (patient has antibodies against something in this sample)
What goes wrong in transfusions?
Transfusion rxn: hemolytic (more serious) or non hemolytic
Infections
Circulatory overload
Iron overload
Graft-versus-host disease
Acute Hemolytic Transfusion Reactions
-when pt has ABO antibodies against donor red cells
Usually a clerical error :(
Acute Hemolytic Transfusion Reactions:
Symptoms:
Labs:
Symptoms: fever, chest pain, hypotension
-Hbg in serum & urine(pink)
Labs: decreased haptoglobin
increased bilirubin, DAT ++
Type and cross-match shows ABO mismatch
Delayed Hemolytic Transfusion Reactions:
-occurs days after transfusion
- caused by antibodies to non-ABO antigens
- Hemolysis usually extravascular
- presentation: falling Hgb after transfusion
- usually NOT severe
Febrile Transfusion Reactions: non hemolytic
symptoms?
Diagnosis? -rule out everything else
Tx?
-Recipient antibodies against donor WBC
Cytokines –> fever, headache, nausea, chest pain
Tx? Tylenol. Leukocyte-reduced components
Allergic Transfusion Reaction?
- most common complication
- non hemolytic
-Probs a host reaction to donor plasma proteins
HIVES!
Tx? hmmm – Antihistamines
Maybe my patient is having a transfusion reaction… what should I do?
STOP THE TRANSFUSION
- check if right blood, right patient
- monitor vitals
- send blood, urine, and bag to blood bank
- Lab will do DAT, ABO/Rh testing, look for hemoglobinuria
Acute Hemolytic Transfusion rxn - What do we worry about?
Lysis of RBC and the release of the contents can cause kidney damage.
Infection Danger of Transfusions?
symptoms and tx?
- uncommon
- Transfusion-related BACTERIAL infection (most common)
- Sudden fever and shock
- Test patient and blood unit!
tx: aggressive resuscitation and antibiotic therapy
What infections do we test blood for?
HIV (very uncommon)
HTLV
Hepatitis B and C (B is more common to get than C)
Syphilis
*Mankato double checks all these!
Other possibilities: EBV, CMV, malaria, lyme’s
Circulatory Overload:
–too much blood is given too quickly
symptoms: hypertension, congestive heart failure
Tx: stop transfusion, give diuretics
Iron Overload
Hey, too much iron can damage heart and liver, remember?
Biggest risk: chronic anemia patients
Tx: iron-chelating agents
Graft vs. Host disease:
Tell me about it…
symptoms?
Prevention?
Donor lymphocytes attack host (immunocomprimised pts or pts with blood relative donors (thanks mom))
Fever, rash, hepatitis, marrow failure
usually FATAL
-prevent by irradiating products
