Transfusion Medicine Flashcards
Why transfuse components rather than whole blood
- conserves blood resources: one donation benefits several patients
- allows storage of components at different temps for optimal function
RBC description
- RBC in various preservative solutions
- STORAGE TEMP: 1-6 C
RBC indications
- anemia w/ compromised clinical status: low hemoglobin
- NOT volume expansion in bleeding patient
RBC usage
- must be compatible with patients ABO blood type
Compatibility of blood types
Type A: B antibodies, A & O compatible
Type B: A antibodies, B & O compatible
Type AB: no antibodies, AB/A/B/O compatible
Type O: A/B antibodies, O compatible
Platelet description
- platelets suspended in plasma
- single donor (apheresis) or pooled (whole blood donor): **6-8 pooled platelets=1 apheresis platelet unit
- STORAGE TEMP: 20-24 C
Platelet indications
- quantitative: bleeding w/ low platelet count, prevent bleeding w/ low platelet count (
Platelet dosage
- 1 apheresis unit or 6-8 pooled units (pediatrics 10mL/kg)
- compatibility w/ patients blood type NOT essential
Plasma description
- frozen w/in 8-24 hrs of collection
- STORAGE TEMP:
Plasma indications
- multiple coagulation deficiency (INR>1.8) AND bleeding or invasive procedure
- congenital coagulation factor deficiency
- NOT volume expansion
Plasma dose
- 4-6 units (pediatrics 15 mL/kg)
- advisable to be blood type compatible
- give as BOLUS
Plasma & INR
- easy to decrease very high INR
- hard to normalize slightly elevated INR
Cryoprecipitate description
- large MW proteins: factor XIII, fibrinogen, vWF+factor VIII
- STORAGE TEMP:
Cryoprecipitate indications
- fibrinogen deficiency & bleeding or invasive procedure: quantitative (
Blood Components
- RBCs, platelets, plasma, cryoprecipitate
Elements of safe transfusion practice
- high quality blood products: healthy donors, sterile collection, storage
- good clinical practice: appropriate indications, avoid errors, monitor for reactions
Hazards of transfusion
- 15% incorrect blood component
- 19% handling & storage errors
- 9% avoidable/delayed/undertrasfusion
- 19% anti-D formed due to no/incorrect amount of Rh immune globulin given
Alternatives to allogenic blood transfusion: rationale
- conserves limited blood supply
- avoids some of risks w/ transfusion
- treatment of patients w/ contraindications
Alternative to allogenic blood transfusion
- hematopoetic growth factors
- pharmacologic agents of hemostasis
- volume expanders
- autologous blood collection
Hematopoetic growth factors
- EPO to limit chronic RBC transfusions
- Romiplostim (thrombopoietin analogue) to avoid prolonged thrombocytopenia & risk of platelet transfusion
Pharmacologic agents of hemostasis
- procoagulants: desmopressin, recombinant factor VIIa, prothrombin complex, factor VIII/iX concentrates, fibrin sealants (topical)
- antifibrinolytics: aprotinin, tranexamic acid, aminocaproic acid
Volume Expanders
- crystalloid: saline/hypertonic saline–add volume, pull fluid from inside cells (SHORT term) & distribute in intravascular/extravascular spaces
- colloid: albumin, dextran, hydroxyethyl starch–pull fluid from interstitial space (LONG acting) & distribute in intravascular ONLY
Autologous blood collection
- preoperative donation: elective procedures likely to require transfusion, patient must have adequate hematocrit & time to replace RBC
- intra/post operative blood recovery: shed blood recovered from surgical field or drain–washed, filtered, reinfused w/in 24 hours
Steps in blood administration
- decision made to transfuse
- pre transfusion blood same testing
- appropriate unit selected
- blood transported to clinical unit
- blood transfused
Testing prior to blood product issue (compatibility testing)
- blood type
- antibody screen
- crossmatch
Blood type testing
- determination of blood type and Rh (D) Ag
- required before any products issued for nonemergent transfusion
- if RBC required emergently, young females receive O Rh negative & everyone else receives O Rh positive units*
Antibody screen
- test for Ab specific for clinically relevant RBC Ag other than ABO
- Ex: if anti-kell detected, patient shouldn’t receive kell+ RBC transfusions
- **required before RBCs are issued for nonemergent transfusion
Crossmatch: positive antibody screen
- test plasma w/ cells from RBC units to be transfused
Crossmatch: negative antibody screen
- computer determine compatibility of unit for patient based on ABO & Rh D type only
Immediate transfusion reactions
- occur during transfusion or w/in 6 hrs
- categories: hemolytic, febrile, allergic, fluid overload, TRALI, septic
First treatment of suspected transfusion reaction
- STOP THE TRANSFUSION
Acute hemolytic transfusion reaction: cause
- preformed Ab in patient’s plasma causes INTRAVASCULAR lysis
- complement activation causes symptoms
- usually due to anti A or anti B, CLERICAL error
- may be due to other Ab vs RBC Ag (anti-Kell)
Acute hemolytic transfusion reaction presentation
- signs: fever, chills, hypotension, chest/back pain
- lab findings: hemoflobinemia, hemoglobinuria, persistent anemia, INCREASED LDH & bilirubin (indirect), low or undetectable haptoglobin, spherocytes
Key lab finding in acute hemolytic transfusion reaction
- positive direct antiglobulin test (DAT): identifies Ab on the transfused cells in the patients circulation
Acute hemolytic transfusion reaction prevention
- ensure accurate patient identification: pretransfusion sample, blood product administration
Febrile transfusion: cause
- release of inflammatory mediators (IL-1/8) from WBC or platelets–PGE2 production–hypothalamic drive to increase body temp (WBC or platelets release mediators in vitro (storage) & patient Ab to WBC releases mediators in vivo
Febrile transfusion reaction: presentation, prevention
- presentation: ISOLATED fever/chills
- prevention: antipyretics, leukocyte reduction of RBC or platelets at collection
Allergic transfusion reaction: cause
- patient Ab to plasma protein: ex. anti IgA in IgA deficient patient
Allergic transfusion reaction: presentation, prevention, treatment
- presentation: hives, rarely dyspnea, hypotension
- prevention: washed RBC to remove allergen, product from IgA negative donor (rarely)
- treatment: antihistamine, epinephrine
Transfusion associated circulatory overload: cause
- too much volume infused rapidly
- at risk: renal insufficiency, chronic anemia
Transfusion associated circulatory overload: presentation, prevention
- presentation: dyspnea, hypertension, pulmonary edema–lab evidence = elevated B-natriuretic peptide
- prevention: transfuse slower, concurrent diuretic administration
TRALI: transfusion related acute lung injury
- transfusion associated noncardiogenic pulmonary edema
TRALI: cause
- donor anti HLA or anti leukocyte Ab reacting with patient WBC: risk highest with plasma/platelet transfusion
TRALI: presentation & prevention
- presentation: HYPOXIA w/ in 6 hrs of transfusion, may require transient ventilator support
- prevention: minimize collection of products from donors with these Ab, eliminate donors whose previous donations have resulted in TRALI
Septic transfusion reaction: cause & presentation
- cause: bacterial contamination of RBC or platelet product
- presentation: fever, chills, hypotension
Septic transfusion reaction: lab evidence & prevention
- labs: positive blood culture from patient matches blood culture from blood product
- prevention: careful screening of blood donors for infection, sterile collection and storage techniques
Delayed transfusion reations
- occur days-weeks after transfusion (or longer)
- categories: hemolytic, graft vs host disease (GVHD), iron overload, transfusion transmitted viruses/parasites/prions
Delayed hemolytic transfusion reaction: causes
- primary or anamnestic (memory) Ab response to RBC Ag results in EXTRAVASCULAR hemolysis of transfused RBC
- Ab results from pregnancy or previous transfusion
Delayed hemolytic transfusion reaction: presentation & prevention
- presentation: malaise–labs: decreased Hb days to wks after, positive DAT, appearance of new RBC Ab, increased conjugated (direct) bilirubin
- prevention: educate patient about any anti RBC Ab detected during pretransfusion testing so they can inform future health care providers
Transfusion associated GVHD: cause & presentation
- cause: infusion of T cells that recognize patient cells as foreign, while patient T cells don’t recognize donor cells as foreign
- presentation: fever, skin rash, diarrhea, hepatitis, AND marrow aplasia (10-12 days after transfusion)
Transfusion associated GVHD: treatment & prevention
- treatment: nothing effective, >95% lethal due to BM failure
- prevention: irradiate cellular blood products (at least 2500 cGY) for: immunocompromised patients (not HIV), recipients of blood products from 1st degree relatives
Iron overload transfusion reaction: cause & presentation
- cause: numerous chronic RBC transfusions w/ out blood loss: aplastic anemia, sickle cell, thalassemias
- presentation: high ferritin, eventual hemosiderosis in heart, liver, pancreas
Iron overload transfusion reaction: prevention/treatment
- RBC exchange rather than simple transfusion for qualitative defects (sickle cell), chelation therapy (deferocamine, deferasirox)
Transfusion transmitted viruses: blood screened
- HCV, HIV, HBV, HTLV I/II, west nile
Leukocyte testing for transmitted infections
- cytomegalovirus (CMV)
