module 9

• Blood transfusion


  Essentially a transplant of foreign cells into the recipient
• Transfusion therapy

  A broad term that encompasses all aspects of the transfusion of patients

  
• Each blood component has specific indications for use, expected outcomes, and other considerations
• Transfusion of blood cells


  Cells must survive and function after transfusion to have a therapeutic effect
• Transfusion reactions


  Many adverse events are related to the introduction of foreign cells/proteins into the recipient
• Following recognition of a suspected transfusion reaction


  1. Stop the transfusion if still in process

  2. Send appropriate specimens to the lab for investigation
• Identify a possible hemolytic transfusion reaction

  1. Check appropriate identification of component, label, paperwork, recipient's pretransfusion specimen

  2. Repeat ABO testing on post-transfusion sample

  3. Visual inspection for hemolysis

  4. Perform direct antiglobulin test on post-transfusion specimen

  5. Provide results to Blood Bank supervisor or medical director

  
• Alloimmunization to RBC antigens


  Development of antibodies following RBC transfusion, pregnancy, or transplantation
• Alloimmunization can complicate patient care and increase the risk of immediate and delayed hemolytic transfusion reactions
• Incidence of alloimmunization


  • Less than 0.3% in healthy blood donors
  • 1-3% in unselected hospitalized patients
  • 3% in post-transfusion surgery patients
  • 30% or greater in chronically transfused patients
• Acute hemolytic transfusion reaction (AHTR)


  Accelerated destruction of transfused RBCs due to antibody-mediated incompatibility
• AHTRs occur within minutes after the start of transfusion or within a few hours after completion
• Acute hemolytic transfusion reactions


  • Pain is a common symptom, often localized
  • Hypotension occurs in about 50% of AHTRs, shock in a small subset
• Immediate hemolytic transfusion reaction

  Reaction period varies from 1-2 hours, main cause is misidentification
• Febrile nonhemolytic transfusion reaction (FNHTR)


  Fever greater than 100.4°F or change of at least 1.8°F from pretransfusion, occurring during or within 4 hours after transfusion, with chills/rigors

  
• Prior to leukoreduction, FNHTRs were caused by recipient antibodies triggering release of proinflammatory cytokines
• Allergic transfusion reactions (ATRs)


  Most common reactions seen with platelet and plasma-derived product transfusions, occurring in about 2% of cases
• Terms used to categorize ATRs


  • Allergic
  • Anaphylactoid
  • Anaphylactic
• Allergic transfusion reactions


  • Generally mild to moderate, limited to skin and gastrointestinal tract
  • Most common manifestations are mucocutaneous reactions like urticaria, pruritus
• IgE-mediated type I hypersensitivity does not explain all ATRs, some are due to antibodies against plasma proteins like IgA and haptoglobin
• Transfusion-related acute lung injury (TRALI)


  Rare event associated with transfusion, a leading cause of transfusion-related mortality
• Diagnosis of TRALI


  1. Absence of acute lung injury prior to transfusion

  2. ALI during or within 6 hours after transfusion

  3. Evidence of hypoxemia

  4. Radiographic evidence of pulmonary edema

  5. Exclusion of other causes
• Transfused anti-leukocyte antibodies are implicated in the pathophysiology of TRALI
• Bacterial contamination


  Occurs when a bacteria-contaminated blood component is transfused, most commonly platelets
• The most common isolated cases in red cell products is Yersinia enterocolitica
• Transfusion-associated circulatory overload (TACO)


  Acute respiratory distress from pulmonary edema due to increased intravascular volume and/or impaired cardiac/pulmonary/renal function
• TACO generally occurs within 6 hours after the start of transfusion but may take up to 72 hours to be seen
• Brain natriuretic peptide (BNP)


  Measurement may be helpful in TACO diagnosis, a value 2 times greater than pretransfusion supports the diagnosis
• TACO treatment


  Diuresis and measures to stabilize the patient, depending on severity
• Transfusion-associated graft-versus-host disease (TA-GVHD)


  Clinical syndrome developing from donor lymphocytes after transfusion characterized by skin rash, diarrhea, fever, enlarged liver, elevated liver enzymes, marrow aplasia, and/or pancytopenia

  
• TA-GVHD


  Caused by an immunologic attack by viable donor lymphocytes contained in the transfused blood component against the transfusion recipient
• Treatment for TA-GVHD


  Immunosuppressive medication e.g. corticosteroids
• Post-transfusion purpura (PTP)


  Rare transfusion reaction with severe and sudden drop in platelet count, usually occurring 5 to 10 days after transfusion due to alloimmunization to platelet-specific antibodies from prior transfusion or pregnancy
• Implicated alloantibodies in PTP


  Human platelet antigens HPA-1a or HPA-3a
• Platelet count in PTP

  Usually less than 10,000
• Symptoms of PTP


  Purpura, bleeding from mucous membranes, GI bleeding, hematuria
• First line treatment for PTP


  Intravenous immunoglobulin (IVIG)
• Next option for PTP if IVIG doesn't work

  Plasma exchange with FFP
• Transfusion-associated hepatitis can be caused by HAV, HBV, HCV, HDV, or HEV
• HIV-1 and HIV-2


  Etiologic agents of AIDS