Transfusion Medicine Flashcards
what is the clinical management of anemia rules, when to transfuse and when not to transfuse?
ASA: “RBC transfusion if rarely indicated when the Hgb concentration is greater than 10 and is almost always indicated when its less than 6”
Hct<21% is too low, and 30% is high enough
What are the most common causes of transfusion related reactions? What groups of ppl are most susceptible to each?
Minor allergic reaction (0.5-4%) - usually an isolated event
-rxn to donor proteins
-itch, swell, rash -> benedryl, steroids?
-Try saline washed RBCs
Febrile Reaction (0.1-2%)
-recipient Abs to donor WBC HLA proteins
-F/C, nausea,resp. distress, myalgias, HA
-Tx w/acetaminophen
-Distinguish from hemolytic rxn w/neg direct coombs test
-Try leukocyte reduced products
- Immunosupressed pts should get this
explain the body’s compensatory mechanisms to anemia.
- increased cardiac output (Decreased SVR -> Inc SV)
- CO redistribution (Brain, Heart > muscles, skin, viscera)
- Coronary flow incr by up to 500%
- Incr O2 extraction (but not in the heart)
- Change O2-Hb affinity (Hgb < 9 -> R shifted curve)
The heart can get more blood flow but cannot incr the amount of O2 extracted. The liver, kidneys and brain can do a better job at extracting O2 from blood. Heart has ER of 55 to 70% at baseline.
Who can receive blood from whom?
Of course you can always give A blood to persons with blood group A, B blood to a person with blood group B and so on. But in some cases you can receive blood with another type of blood group, or donate blood to a person with another kind of blood group.
The transfusion will work if a person who is going to receive blood has a blood group that doesn’t have any antibodies against the donor blood’s antigens. But if a person who is going to receive blood has antibodies matching the donor blood’s antigens, the red blood cells in the donated blood will clump.
O has no antigens, so it is the universal donor. Anyone can receive it bc there is no such thing as anti-O antibodies. But O can only receive O because it has anti-A and anti-B antibodies
AB has no antibodies so it can accept any type of blood and is the universal recipient. It has both A and B antigens.
Does FFP need to be ABO and Rh compatible?
FFP does not need to be cross-matched but should be ABO compatible. Group O FFP only should be transfused to group O recipients but O can receive A,B,AB,and O plasma. It is the universal recipient. This is opposite from PRBC compatibility. AB is the universal FFP donor but can only receive AB FFP.
What are the universal donors and recipients for pRBCs and FFP?
pRBCs - universal donor = O
- universal recipient = AB
FFP - universal donor = AB
- universal recipient = O
O has no antigens (receptors) and both A and B antibodies
AB has both A and B antigens (receptors) and no aantibodies
What is the difference between type and screen and type and cross?
Type and screen determines the pts ABO and Rh type. It also tests for about 25 specific antibodies that are clinically significant. Type and cross goes a step further to determine if there are any antibodies in the recipients serum that is going to react with the donors RBCs.
What is the difference between Rh+ and Rh- blood?
Rh + blood - D-antigens (85% of the population)
Rh - blood - anti-D antibody develops with exposure to Rh+
RH+ means that a person carries the RH atntigen. Rh- means that the person does not carry the RH antigen
The Rh factor assumes a special importance in maternal-fetal interactions. A mother who is Rh- can bear an Rh+ child if the father is Rh+ (either homozygous or heterozygous). Since there are no natural anti-Rh antibodies, this generally poses no special risk for the first pregnancy.
Many people also have a so called Rh factor on the red blood cell’s surface. This is also an antigen and those who have it are called Rh+. Those who haven’t are called Rh-. A person with Rh- blood does not have Rh antibodies naturally in the blood plasma (as one can have A or B antibodies, for instance). But a person with Rh- blood can develop Rh antibodies in the blood plasma if he or she receives blood from a person with Rh+ blood, whose Rh antigens can trigger the production of Rh antibodies. A person with Rh+ blood can receive blood from a person with Rh- blood without any problems
What are the 4 vitamin K dependent factors?
Factor II, VII, IX, X
What 4 factors are part of the extrinsic pathway?
Factors II, V, VII, X
Hemophilia A is characterized by what factor deficiency?
Factor VIII deficiency
What is the three step process for coagulation?
Activation, amplification and propogation
Factor IIa is also known as what?
Thrombin
Clotting factors are all inactive pro-enzymes that are all, with the exception of one factor, synthesized where? What is the exception?
All synthesized in the liver except for factor VIII
What is vWF deficiency characterized by?
poor platelet adhesion AND clinical hemophilia A
