Transfusion medicine Flashcards
Blood component collection
All 3 components are separated without being opened to avoid contamination –> need to be separated because all are stored differently
- RBCs = 1-6 C for 21-42 days
- Platelets = room temp for 5 days
- Plasma = frozen until needed
Separating components
- Soft spin –> separates RBCs and platelet rich plasma
Hard spin –> separates platelets/leukocytes from plasma
- Platelets undergo leukoreduction to get rid of white cells –> leukocytes are the source of adverse reactions people have to transfusions
Cryoprecipitate –> certain proteins that remain as a precipitate when plasma is thawed at 4 C
Use sterile tubing welder to enter the closed system –> prevents microbial contamination
Apheresis
Can be used to extract only what we want from a blood donor
- limits the person receiving the transfusion to only a single donor
Also use to collect hematopoeitic stem cells
Factor concentrate
Manufactured commercially
- VIII
- IX
- fibrinogen
- antithrombin
- protein C
- VIIa
- prothrombin complex = II, IX, X, XII
VIIa = 2 approved uses:
- hemophiliacs with autoantibodies against VIII
- factor VII deficiency
Type and screen vs. type and cross
Type and screen –> testing a patient to see if they have ABs against any clinically relevant antigens in case they need a transfusion
Type and cross –> AB screen + cross matching tests –> done when you know you’re going to use blood
ABO system
Type A = have A antigens –> make anti B ABs
Type B = have B antigens –> make anti A ABs
Type AB = have A + B antigens –> no ABs
Type O = no antigens –> make anti A + B ABs
Universal donor
- type O cells –> no antigens
- type AB plasma –> no antibodies
Incompatibility causes intravascular hemolysis
Rh system
Rh positive = D positive –> highly immunogenic
- don’t want to expose Rh- women to Rh+ blood because they could develop an alloantibody and subsequently attack RBCs of the fetus it is Rh+ = hemolytic disease of the newborn
Origin of antibodies in blood
Pregnancy and transfusions
Must avoid giving patients antigen negative blood even if they become AB negative –> still give antigen negative blood because they could have a delayed hemolytic reaction 7-10 days later
Plasma transfusion
Platelet transfusion
Plasma transfusion –> ABO antibodies in plasma must be compatible with patients blood type; Rh doesn’t matter
Platelet transfusion –> don’t have many antigens on surface
- not as careful with platelets about type matching
- Rh not on platelets but if they’re contaminated by RBCs they could cause alloantibodies to develop (rare)
Platelet alloimmunization
When cancer patients are given repeated platelet transfusions, they can develop anti-HLA antibodies against MHC I expressed on the platelet surfaces
- can become refractory to transfusions
- non-immune reasons can cause platelet refractoriness too (splenomegaly –> platelets sequestered in the spleen)
Distinguishing between immune and non-immune by doing 10 and 60 minute counts
- immune –> no increase in platelet count at all
- non-immune –> initial increase in count at 10 min but it will not be sustained at 60 min
If immune –> provide HLA matched or cross matched platelets
Most common microbial contaminant
Babesiosa –> very rare, usually from platelet contamination (stored at room temp)
Acute hemolytic reaction due to ABO incompatibility
Signs/symptoms
- pain
- chills/fever
- rapid HR
- bleeding/DIC
- renal failure
- hemoglobinemia, hemoglobinuria
- fatal 10% of time
Lab findings –> intravascular hemolysis
- hemoglobinemia, hemoglobinuria
- decreased haptoglobin
- increased LDH
- increased unconjugated bilirubin
Delayed hemolytic reaction
Amnestic response
- occurs ~1 week after transfusion
- IgG antibodies
Manifestations
- decreased hct
- jaundice
- fever
Non-hemolytic febrile illness
Increase in temp ~1C +/- chills +/- rigors
- due to recipient anti-leukocyte ABs
Tx = anti-pyretics, tylenol
Allergic reactions
Common –> hives
More severe –> angioedema + bronchospasm
Rare = anaphylaxis
Washing platelets decreases remaining number of leukocytes –> prevents this reaction
Tx = anti-histamines or epi if severe
Transfusion related acute lung injury
Non-cardiogenic pulmonary edema developing 6 hours after beginning a transfusion
- fevers, chills, hypotension, dyspnea, hypoxia
- most commonly with plasma and platelets
- diffuse pulmonary edema on CXR
- pulmonary capillaries damaged by activated neutrophils
- potential activators = donor anti-leukocyte antibodies in most cases
Prevention –> removal of donor from donating pool
Tx –> supportive, help them breath until they recover
Most common cause of transfusion related deaths
