Transfusion Medicine

Question 1

Donor Health Questionnaire

Aims

Answer 1

• Screen for Infectious Diseases (known and unknown)
• Screen for behaviors that may place donor in ‘Window Period’ for known Infectious Diseases
• Identify Donor Medications that may affect recipient

Question 2

RBC Antigens

Answer 2

• RBCs express numerous proteins other than Hb
• Proteins can be found on surface of RBC ⇒ pts most often form Ab against that can cause hemolysis
• Enzymes catalyze synthesis of polysaccharide chains attached to external surface of RBC
• Inheritance of these enzymes ⇒unique RBC antigens that can be clinically significant
• Best example of this is the ABO group

Question 3

Hemolytic

Transfusion Reactions

Answer 3

• Caused by transfusion of incorrectly typed blood
• Results in destruction of donor RBCs by recipient immune system
• Two types: Intravascular vs Extravascular Hemolysis

Question 4

Intravascular Hemolysis

Answer 4

• Rxn occurs within blood vessels
• More severe type
• Donor RBC antigens bound by recipient Ab (usu. IgM)
• Complement activation ⇒ MAC complex ⇒ RBC lysis into schistocytes ⇒ release of Hb & cytokines
• Main sx caused by effects of cytokines ⇒ hypotension, DIC, fever
• Additional symptoms:
  
  • Chills/rigors
  • Anxiety
  • Dyspnea
  • Chest pain
  • Flank pain/Renal failure ⇒ caused by excess Hb
  • Sense of impending doom

Question 5

Extravascular Hemolysis

Answer 5

• Ab and complement binds to mismatched RBCs
• Marks them for targeting to liver and spleen instead of destroying
  
  • Part of reticuloendothelial system
  • Acts as a sink for collection/destruction of labeled RBCs
• RBCs cleared by MΦ
• Symptoms:
  
  • Fever
  • Malaise
  • ± Mild jaundice

Question 6

Blood Typing

Answer 6

• ABO/Rh types
• Forward typing
  
  • Tests for what is on pt cells
  • Pt cells added to anti-sera
  • If pt has Ab on RBC ⇒ ⊕ reaction ⇒ agglutination
• Reverse
  
  • Pt plasma added to known reagent cells
  • If pt has Ab vs specific RBC Ab ⇒ ⊕ reaction ⇒ agglutination
  • Only done for anti-A and anti-B Abs ⇒ naturally occurring
  • Anti-D not done b/c only make when exposed to D ⊕ blood

Question 7

Blood Compatibility

Answer 7

Match based on Ab that recipient plasma would contain.

Question 8

Crossmatch

Answer 8

Done to prevent compatibility:

Question 9

Alloantibody Formation

Answer 9

Question 10

Emergency Transfusions

Answer 10

• Emergent situations
  
  • Delays in transfusing blood components can be riskier than transfusing untested blood
  • Must complete emergency release prior to giving
  • What type of RBCs? ⇒ O type
  • Women < 50 y/o always get Rh^⊖ blood to prevent hemolytic disease of the newborn
  • Males of any age get Rh^⊕ blood
  • What type of FFP? ⇒ AB plasma
• Massive Transfusion Protocols:
  
  • Ensures large amounts of blood, at an appropriate ratio (RBC:Plasma:Platelets), are quickly distributed

Question 11

Septic Transfusion Reaction

Answer 11

• Caused by transfusion of PRBCs containing a large bacteria load
  
  • Don’t check RBCs for infection
• Sx can include:
  
  • Fever
  • Tachycardia
  • Hypotension
  • Rigors/shaking chills
  • Shock/LOC
  • N/V
  • Dyspnea
  • Wheezing
  • Pain
  • Diarrhea
  • Pain at infusion site
  • Headache
• Factors affecting likelihood of reaction:
  
  • Storage Time
  • Concentration of Bacteria
  • Recipient Immune Status
  • Species
    
    • RBCs: often Gram-⊖ organisms (LPS)
    • Platelets: often Gram-⊕ organisms (skin flora/contaminants)

Question 12

Transfusion Related Acute Lung Injury

(TRALI)

Answer 12

• Insidious onset of acute pulmonary insufficiency (76%) presenting as:
  
  • Tachypnea, cyanosis, dyspnea
  • Acute hypoxemia (PaO2/FiO2 < 300 mmHg or SPO2 <90% on RA)
  • No evidence of ↑LA Pressure
  • ↓ Pulmonary compliance
• CXR: diffuse, fluffy infiltrates
• Additional sx: fever
• Caused by transfusion of usu. yellow products with Ab vs components in pulmonary interstitium
• During/within the 6 hours of transfusion
  
  • > 90% within 1-2h
  • 100% within 6h
• Clinical diagnosis

Question 13

Transfusion

Allergic Reaction

Answer 13

• Continuum of presentations
• Minor allergic rxns common
• Anaphylactic rxns rare

Question 14

Transfusion-Associated Circulatory Overload

(TACO)

Answer 14

• Caused by fluid overload
• New-onset/exacerbation of ≥ 3 within 6h of transfusion:
  
  • Acute Respiratory Distress
  • Evidence of ⊕ fluid balance
  • Elevated BNP
  • Radiographic pulmonary edema
  • Evidence of left heart failure
  • Elevated CVP
• #1 cause of mortality associated w/ transfusions
• Preventable w/ slow infusion of appropriate amount

Question 15

TA-Graft-Versus-Host Disease

Prevention

Answer 15

• Irradiation (> 25 Gy) renders 85-95% of lymphocytes incapable of replication
• Performed on (non-frozen components):
  
  • o RBCs
  • o Platelets
  • o Granulocytes
  • o Whole Blood
• Only prevention for TA-GVHD

Question 16

Transfusion Reactions

Management

Answer 16

Question 17

Transfusion Indications

Answer 17

Question 18

Summary

Answer 18

• Blood utilization is expensive and can be associated with severe complications
• Most transfusions, however, are not associated with complications
• Certain patient populations have special needs and require modified blood products
• Managing a transfusion reaction requires its identification (now you know how to do this)
• When in doubt, consult a Pathologist!