Principles of Blood Banking Flashcards
blood components
*whole blood
*red blood cells
*plasma (fresh frozen & 24 hr)
*platelets (single donor & whole blood derived)
*cryoprecipitate
*granulocytes
collection strategy - apheresis
*same as phlebotomy (except we can collect more)
*single donor-RBCs, platelets, plasma
*white blood cells (granulocytes, monocytes, T cells, stem cells)
*basically, separates out a single component and re-infuses the other components that we are not specifically wanting
*usually takes about 90 min
donation of 1 unit of whole blood yields:
*1 unit of packed red blood cells (PRBC)
*1 unit of random donor platelets
*1 unit of plasma (FFP or 24 hr)
*1 unit of cryoprecipitate
pre-transfusion testing of donor blood
*ABO & Rh and antibody screen
*RPR (looks for syphillis)
*HBsAg
*HBcAb
*HBV nucleic acid test
*HCV
*HIV 1 & 2
*HTLV-I/II
*west nile virus
*bacterial culture (platelets)
*chagas disease
*babesia
indication for whole blood transfusion
*transfuse (1-4 units) to treat massive hemorrhage [provides all blood components]
*massive transfusion protocol (1:1:1)
*stored in the refrigerator at 1-6 deg C
indication for packed RBC transfusion
*transfuse (1-2 units) to treat anemia
*hemoglobin usually < 7
*stored in the refrigerator at 1-6 deg C
*1 unit will increase the Hb by 1 g/dL in adults and increase Hct by 3% (pediatric: Hb increase by 2-3)
massive transfusion of PRBCs
*defined as replacement of 1 total blood volume (usually 10 units of PRBC) in less than 24 hours
*may be complicated by dilutional coagulopathy, hypocalcemia, hyperkalemia, arrhythmia
*7-10 units of plasma (1:1)
indication for platelet transfusion
*transfuse 1 unit for thrombocytopenia
*platelet count usually < 10k
*stored at room temperature (note - risk of bacterial contamination)
indication for plasma transfusion
*note - plasma contains everything in normal human plasma (all clotting factors, and ADAMTS13)
*plasma transfusions are typically used to replace multiple clotting factors at the same time:
-disseminated intravascular coagulopathy (DIC)
-to reverse warfarin
*transfuse (2 units) to treat clotting factor deficiencies
cryoprecipitate - overview
*cryo is made from FFP (fresh frozen plasma) but only provides more concentrated form of:
1. FIBRINOGEN (think of this as a fibrinogen transfusion)
2. factor VIII
3. von Willebrand factor
4. factor XIII
5. fibronectin
what are blood groups
*red blood cells express antigens on their cell surface
*some of these antigens are very relevant to patient safety when transfused:
-ABO
-Rh
-Kell, Duffy, Kidd, Ss, etc
-36 blood group systems (>300 separate RBC antigens)
RBCs - group O / “H” antigen
*H antigen is present on all human RBCs
*think of H as the “O” antigen
*H is the precursor of the A & B antigens
key point with the ABO system and antigens/antibodies
*you will NATURALLY have the ANTIBODY that is NOT your blood group:
-group A person: anti-B antibodies
-group B person: anti-A antibodies
-group AB person: NO ABO antibodies
-group O person: both anti-A & anti-B antibodies
Rh blood group - overview
*the D antigen (+ indicates that someone HAS the D antigen; - indicates that they do not have the D antigen)
*antibodies to D antigen are NOT “naturally” occurring - [ie. a D- person needs an EXPOSURE to foreign, non-self RBCs to have an antibody response (pregnancy, blood transfusion, bone marrow transplant, organ transplant)]
“type” in testing for blood transfusions
*check a patient’s (the recipient’s) ABO and Rh type
*forward type: test the PATIENT’S red cells for A or B antigen
*Rh type: test the red cells for the D antigen
*reverse type: test the PATIENT’S serum/plasma for the expected antibody (ex. if you know the pt is type A, you are checking for anti-B antibodies in the serum)
“screen” in testing for blood transfusions
*check the PATIENT’S (the recipient’s) serum/plasma for other antibodies against red cell antigens (other than ABO, such as Kell, Duffy, Kidd…)
*more relevant after a patient has already had a blood transfusion before
“cross” in testing for blood transfusions
*cross = crossmatch:
-mix the PATIENT’S serum/plasma with a sample of the DONOR red cells from the exact unit that we wish to transfuse
-if the red cells and serum mixture clumps, then the unit is INCOMPATIBLE
*endpoint of most blood bank tests is AGGLUTINATION (clumping) which indicates hemolysis
indirect antiglobulin test (antibody screen)
*detects clinically significant RBC antibodies
*screening the patient’s serum for reaction against red cells
summary - more of a pre-transfusion test; patient’s serum with donor RBCs
direct antiglobulin test/DAT (Coombs test)
*demonstrates in-vivo coating of RBCs with antibody or complement-hemolysis
*looking for auto-antibodies to their OWN RED CELLS
summary - PATIENT RED CELLS AND PATIENT ANTIBODIES; looking for antibodies against patient’s own red cells
hemolytic disease of the fetus and newborn (HDFN) - how does it happen
*mother = Rh NEG
- fetus = Rh pos
- fetal red cells enter maternal circulation
- mother synthesizes anti-D antibodies
- anti-D crosses placenta and hemolyzes fetal red cells
problematic with the SECOND pregnancy (antibodies formed in first pregnancy)