Flashcards in Week 6 HRM - Transfusion Deck (29):
What are the two major blood groups involved in blood typing?
ABO and Rh
What is serum?
The acellular component of blood left behind after clotting has occurred, meaning that it won't contain fibrinogen or clotting factors
(It will contain nutrients, other proteins, gases, hormones etc)
What are naturally occurring antibodies?
These antibodies are present in a person which act against the antibodies of the blood type which they do not express. This applies to the ABO system
(I.e. Blood type A person will express natural antibodies to blood type B)
On a molecular level, what determines s person's ABO blood type?
The antigen consists of a string of sugars attached to the membrane and the type of sugar on the end of the chain determines what blood type.
What antigens will someone with blood type O possess?
Naturally occurring antibodies for both A and B
What are immune antibodies?
Develop after introduction of antigen to via transfusion or transplacental passage
Why does matching of blood need to occur before transfusion?
So that there isn't a haemolytic reaction that cause massive destruction of the blood cells, often fatal.
What percentage of transfusions are safe purely based on matching the ABO and Rh blood type?
98% (further testing is done to make 100% sure that reaction will not occur)
What is the proportion of Rh negative status, and how is Rh blood type determined?
Generally over 90% of Australians are Rh pos.
3 alleles contribute to the Rh group, and only if recessive for all 3 alleles will it be negative
What diseases/infections are screened for in blood donations?
Hepatitis, HIV, syphilis, cytomegalovirus and T cell leukaemia virus I
What is a direct Coombs test?
It is where RBCs are taken and incubated with anti human globulin, which if it binds and causes agglutination of the RBCs shows that there is antibodies bound to the RBC.
What is an indirect Coombs test?
Using antibodies to see if there are any antibodies freely found in serum. Used to test pregnant women to see if they have antibodies for RhD.
Different to direct as it is detecting an immune response on RBC membranes
What is anti human globulin?
Made by injecting animals with human globulin. They produce antibodies for human globulins. When you add them to a blood sample, if they bind to the blood cells or the antibodies, it shows that there is an immune reaction taking place.
What is cross matching of the blood before transfusion?
Testing the RBCs of donor against the serum of the patient to see if any reaction takes place. Used to ensure no reaction takes place in blood transfusion where the donors have the same ABO and Rh groups.
(This is done after the ABO and Rh blood groups have been matched)
What is the cause of the Rh D negative status?
The gene that encodes the Rh D protein may be absent from the genome, leading to an Rh- blood type. This is why when it is exposed to a Rh+ cell, it mounts an immune response against thenRhD antigen and antibodies form against it
What is alloimmunisation?
The body's immune response to interaction with a human cell/tissue. It is essentially immunity against a human derived antigen
What is the most common immediate immune complication of blood transfusion?
What are some of the non immunological complications immediately following transfusion?
What occurs in a haemolytic reaction?
Intravascular haemolysis due to activation of IgM and IgG antibodies binding to the RBCs
Extravascular haemolysis occurs when Rh antibodies form, which is less severe but still can be life threatening.
What are some delayed immunological complications associated with transfusion?
Delayed haemolytic reactions and alloimmunisation
How could an allergic reaction occur following a transfusion?
The patient could be hypersensitive to donor plasma proteins which can result in anaphylactic shock
What are some delayed non immunological complications following transfusion?
Infectious disease acquired through transfusion, including viruses, bacterial or parasites
Also can cause iron overload (only in repeated transfusion, chronic renal disease)
When is transfusion of RBCs indicated?
When there is a need to increase oxygen delivery capacity in a short period of time
What conditions usually require RBC transfusion?
Renal failure (lack of EPO)
Bone marrow failure
When should you transfuse platelet concentrate?
In severe thrombocytopenia
What is cryoprecipitate?
Is frozen blood product prepared from plasma. Centrifuged from freshly thawed plasma. Contains fibrinogen and is used in aiding clotting.
What is cryosupernant?
The component of plasma left after the cryoprecipitate is removed. Contains platelets and is also given to thrombytopenic patients. Also contains antibodies and can be used to help with passive immunity.
What are the three categories of oxygen carriers that could potentially replace RBCs in transfusions?
2) haemoglobin based oxygen carriers
3) engineered red blood cells