Transfusion - Platelets, Plasma, and Cryoprecipitate

Question 1

What are the types of donation for all blood components?

Answer 1

• Whole-blood: 500 mL collected in 10 min, separated into RBCs, plus 200 mL plasma or 50-60 mL platelets
• Apheresis: donor blood drawn into continuous-flow centrifuge during 45-90-min collection, desired components skimmed off, rest returned to donor
  
  • Collect 1 or 2 300-mL platelet doses, or 2 units plasma, or 2 units RBCs; or
  • Two doses of different components: RBCs plus platelets, etc.

Question 2

What are the contents, doses, and transfusion responses of platelets?

Answer 2

• Product Types:
  
  • Plateletpheresis unit—full adult dose; >90% of US platelet doses
  • Whole-blood platelets—5 units pooled for full adult dose; <10% of US platelet doses
• Storage: 5 days, 20-24°C
• Compatibility: Contains ABO antigens on platelets, anti-A/B in plasma, <1 mL RBCs
  
  • Ideally ABO-matched and Rh(D)-negative for Rh(D)-negative girls and women to avoid Rh(D)+ RBC exposure/risk of anti-D
• Content/Response: content of either apheresis or pool ideally raises adult platelet count by average of 25-30,000/uL immediately, with persisting 10-15,000/uL-increment at 18-24 hr
• Circulating lifespan: 1-2 days in thrombocytopenic patients

Question 3

What are the contents, doses, and transfusion response of plasma?

Answer 3

• Product Types:
  
  • Fresh Frozen Plasma—must be frozen <8 hr after collection for FFP designation, per FDA
    
    • difficult to make fast enough in many regions—minority of US plasma is FFP
  • Plasma—frozen <24 hr of collection; most available plasma is “PF24” per FDA; used same as FFP
  • Pathogen-reduced plasma—Solvent-detergent or photochemically treated plasma
• Storage, FFP and Plasma: 1 year, < -18°C; thawed, 1-6°C for 5 days (pathogen-inactivated, 12-24 hr)
• Compatibility: Contains anti-A/B in plasma
  
  • Ideally give ABO-matched; avoid giving anti-A or -B versus ABO
• Content: 200 mL plasma/dose; normal clotting factor levels
• Response:
  
  • Average plasma volume = 5000 mL total blood volume [70 mL/kg body wt x 70 kg] X (1 - 0.40 hematocrit) = 3000 mL
  • One 200-mL unit plasma added to 3000 mL plasma volume = <6% rise in clotting factor levels
  • >3-4 units needed initially for significant clotting factor deficiency (see Indications below)
• Clotting factor half-lives:
  
  • F VII, 4-6 hr
  • F VIII 12 hr
  • others, 1-2 days

Question 4

What are the contents, doses, and transfusion responses of cryoprecipitate?

Answer 4

• Product: Thaw FFP to just above freezing
  
  • A precipitate forms containing fibrinogen, factor VIII, von Willebrand factor
  • Centrifuge the bag, express off the supernatant, and freeze the cryoprecipitate (15 mL)
  • Adult dose usually 5 units
• Note: Cryo was developed for hemophilia A, but is no longer used for F VIII or vWF therapy
• Storage: 1 year, < -18°C; thawed, 20-24°C for < 6 hr (do not refrigerate and re-precipitate)
• Compatibility: Small volume, 75 mL/dose; ABO matching not necessary
• Content—fibrinogen: FDA requirement (used in some dosing calculations) is >150 mg/unit
  
  • Actualy content averages 400 mg/unit x 5 = 2000 mg/5-pool dose
• Response: 2000 mg into 3000 mL plasma volume => 65 mg/dL rise in plasma fibrinogen/dose, without consumption
• Fibrinogen half-life: 2-3 days

Question 5

What are the indications for platlet transfusion?

Answer 5

• Platelet count <10K/uL without bleeding: transfusion goal >10K/uL to prevent spontaneous bleeding
  
  • Exception: immune thrombocytopenic purpura—autoantibodies usually block rise in platelet count
• Platelet count <50K/uL with bleeding or invasive procedure: transfusion goal >50K/uL
• Platelet count <75-100K/uL & central nervous system (CNS) bleeding/procedure: goal >75-100K/uL
• Platelet dysfunction and bleeding or invasive procedure:
  
  • antiplatelet medications
  • post-cardiac bypass
  • congenital platelet disorder
  • 2 doses of platelets provide 50-60K/uL of functioning platelets
• Massive transfusion (>10 units RBCs) with presumed platelet dilution, pending platelet count

Question 6

What is platelet refractoriness, and what is the appropriate management?

Answer 6

• Post-transfusion platelet count does not rise or persist as expected
• Evaluation: post-transfusion platelet count at 15-60 min, and at 18-24 hr
• Non-immune:
  
  • sequestration (splenomegaly)
  • usage (bleeding, disseminated intravascular coagulation (DIC))
  • high turnover (fever, sepsis)
  • large blood volume (high body weight)—in some cases, good 60-min response but poor 18-24-hr response
• Immune (antibody): suspect if poor 60-min responses
  
  • If ABO-incompatible, try ABO-matched
  • Test for antibodies: HLA Class I (HLA-A, HLA-B), and/or platelet crossmatch for IgG vs platelets
  • Give HLA-matched or crossmatch-compatible platelets
    
    • platelet counts <60 min post-transfusion to assess which donors work

Question 7

What are the indications for plasma transfusion?

Answer 7

• Multiple clotting factor deficiencies and bleeding or invasive procedure
  
  • Liver disease
  • DIC
  • Emergency warfarin reversal, if time does not permit reversal by vitamin K (1 day)
    
    • Note: Four-factor concentrate (II-VII-IX-X) is an alternative to plasma for providing vitamin-K-dependent factors emergently for CNS bleeding or surgery
  • Massive transfusion (>10 units RBCs) with plasma dilution
    
    • 1:1 ratio of RBC units to plasma units is advocated in these patients
• Congenital factor deficiencies when factor concentrates are not available: factor V, factor XI
  
  • Factor concentrates approved in US:
    
    • fibrinogen
    • VII, VIII, IX, and XIII
    • combinations II-IX-X and II-VII-IX-X
• Thrombotic thrombocytopenic purpura (TTP)

Question 8

What are the goals of platelet transfusion?

Answer 8

• Factor levels and clotting tests
  
  • Factor levels vary widely among patients–50-150% of pooled-plasma normal mean
  • Hemostasis adequate for most purposes when factor levels are >30% of normal, approx. equivalent to:
    
    • Prothrombin time (PT) ~1.5 times normal, or International Normalized Ratio (INR) ~1.6
    • Partial thromboplastin time (PTT) ~1.5 times normal
• Plasma transfusion effect on lab values in factor deficiency
  
  • Highly elevated PT/INR (very low factor levels) readily improves with plasma
  • As INR approaches 1.6, further improvement from transfusion is very small
    
    • E.g.: [3000 mL plasma, 30% factor levels] + [1000 mL plasma (5 units), 100% level] = 4000 mL plasma with 48% factor level
  • Complete normalization of factor levels with plasma is not possible with simple transfusion

Question 9

What are the indications for cryoprecipitate transfusions?

Answer 9

• Bleeding or invasive procedure and fibrinogen level inadequate (despite plasma transfusion)
  
  • Plasma fibrinogen <100 mg/dL (normal 200-400 mg/dL)
  • Plasma fibrinogen <200 mg/dL in obstetrical bleeding
• Fibrinogen concentrate recently approved in US—approved only for rare congenital fibrinogen deficiency/dysfunction
  
  • ​In** **many countries concentrate is used instead of cryo—pathogen-inactivated, rapidly infusible