Transfusion Products

Although fresh whole blood was the only product in the early years of transfusion, the advent of whole-blood fractionation techniques has allowed for more efficient use of the various blood components. Fractionated transfusion products, prepared in blood transfusion centers, include RBCs, platelets, FFP, and cryoprecipitate. These products are transfused for different indications and each addresses different pathologies.

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Introduction

  • The 1st human blood transfusion was in 1795.
  • Blood transfusions are a very common medical procedure.
  • 21 million blood components are transfused each year in the United States.
  • Blood and its products are, at a minimum, screened for: 
    • Hepatitis B
    • Hepatitis C 
    • HIV
    • Human T-cell lymphotropic virus (HTLV)
    • Syphilis
  • Donations are ABO and Rhesus factor (Rh) typed and screened.
  • Types of blood products used: 
    • Whole blood
    • Packed RBCs
    • Platelets
    • Plasma
    • Cryoprecipitate
Composition of Blood

A centrifuged tube showing the components in whole blood (plasma, RBCs, platelets, and WBCs)

Image: “The cellular elements of blood include a vast number of erythrocytes and comparatively fewer leukocytes and platelets” by OpenStax College. License: CC BY 4.0
Table: Blood group compatibility for giving and receiving blood
Blood typeGivesReceives
A+A+, AB+A+, A–, O+, O
A–A+, A-, AB+, AB–A-, O–
B+B+, AB+B+, B–, O+, O–
B-B+, B–, AB+, AB–B–, O–
O+A+, B+, O+, AB+O+, O–
O–EveryoneO–
AB+AB+Everyone
AB–AB+, AB–AB–, A–, B–, O–

Transfusion Products

Packed RBCs

  • Created by removal of the majority of plasma from a unit of whole blood:
    • Each unit contains:
      • 200 mL of RBCs
      • 70 mL of plasma
      • 100 mL of additives (citrate as an anticoagulant, phosphate, dextrose)
      • Hematocrit of 65%–80%
      • Volume of 250–300 mL 
      • Can be stored up to 42 days
    • 1 unit should: 
      • ↑ Hemoglobin by 1 g/dL 
      • ↑ Hematocrit by 3% 
  • Additional processing to RBCs:
    • Leukocyte-reduced: 
      • Filtered to remove 85%–90% of WBCs
      • ↓ Risk of adverse reactions
    • Irradiated:
      • Prepared by exposing the unit to 2500 cGy of radiation 
      • Inactivates donor T cells 
      • ↓ Risk of a graft-versus-host reaction in recipient
    • Washed: 
      • Washing RBCs with 0.9% NaCl depletes packed RBCs of most plasma
      • Used for individuals with history of severe allergy to transfusion

Platelets

  • Platelets (thrombocytes) are small, colorless cell fragments.
  • Involved in the formation of clots
  • Pooled platelets: 
    • Separated from a unit of donated blood 
    • 4–6 units are pooled to allow an adequate number of platelets per transfusion.
    • Advantages:
      • ↓ Cost 
      • Ease of collection 
    • Disadvantages:
      • Each recipient is exposed to multiple donors.
      • ↑ Risk of allergic reactions and infections
  • Apheresis platelets:
    • Platelets are selectively removed from blood, which is then returned to the donor.
    • An apheresis platelet unit is equivalent to ≥ 6 units of platelets from whole blood. 

Plasma

  • Plasma is “pooled” in containers (separated from RBCs) and then fractionated.
  • Yellow liquid component of blood
  • Holds proteins and other constituents of whole blood in suspension:
    • Albumin
    • Blood clotting factors (for hemophilia)
    • IV immunoglobulin (IVIG)
    • Globulins
    • Fibrinogen
  • FFP: 
    • Frozen < 8 hours after collection
    • Contains all coagulation factors and proteins
    • Dose: 12–15 mL/kg, but varies on the basis of indication
  • Plasma frozen < 24 hours after phlebotomy (PF24): contains ↓ levels of factor VIII and protein C 
  • Thawed plasma:
    • Can be kept in refrigerator up to 5 days
    • ↓ Levels of factor V and factor VIII
  • Liquid plasma: plasma that has never been frozen
  • Solvent/detergent (S/D): treated with viral inactivating agents prior to freezing
  • Cryoprecipitate reduced: 
    • Cryoprecipitate has been removed.
    • Still contains all vitamin K–dependent clotting factors
  • Convalescent plasma: prepared from individuals who have recovered from infection with a specific pathogen.

Cryoprecipitate

  • Derived from plasma that is frozen ≤ 8 hours after collection (FFP)
  • The plasma is thawed to between 1 and 6°C and subsequently centrifuged.
  • The fraction that precipitates out of solution is collected and refrozen to –18°C.
  • This process creates 1 unit of cryoprecipitate.
  • A transfusion bag contains between 5 and 10 units of cryoprecipitate.
  • Each unit contains:
    • Fibrinogen: 150–300 mg of fibrinogen; half-life: 100–150 hours
    • Factor VIII: > 80 IU (range, 80–150); half-life: 12 hours
    • Factor XIII: 50–75 units; half-life: 150–300 hours
    • von Willebrand factor: 100–150 units; half-life: 24 hours
    • Fibronectin: in variable concentrations

Breakdown of the blood components

Table: Breakdown of the blood components
Blood componentsSubcomponents of the bloodTypeProduction siteMain tasks
Plasma 43%–63%Water 92%LiquidAbsorbed in GI tract or made during metabolismTransport medium
Plasma proteins 7%Albumin 54%–60%Liver
  • Maintains osmotic concentration
  • Transports lipid molecules
Globulins 35%–38%Alpha globulins: liverTransport and maintain osmotic concentration
Beta globulins: liverTransport and maintain osmotic concentration
Gamma globulins (immunoglobulins): plasma cellsImmune response
Fibrinogen 4%–7%LiverBlood clotting during hemostasis
Regulatory proteins < 1%
  • Hormones
  • Enzymes
Various locationsRegulate various body functions
Other dissolved substances 1%
  • Nutrients
  • Gases
  • Waste
  • Absorbed in GI tract
  • Replacement of cells in respiratory tract
  • Made in cells
Many different functions
Formed elements 37%–54%Erythrocytes 99%ErythrocytesRed marrowTransports gases, O2 and some CO2
  • Leukocytes < 1%
  • Platelets < 1%
  • Granular leukocytes
  • Neutrophils
  • Eosinophils
  • Basophils
Red marrowNonspecific immune response
  • Agranular leukocytes
  • Lymphocytes
  • Monocytes
Lymphocytes: bone marrow and lymphoid tissueLymphocytes: specific immune response
Monocytes: red marrowMonocytes: nonspecific immune response
Platelets < 1%Megakaryocytes: red marrowHemostasis

Indications for Transfusion of Blood Products

Indications for RBC transfusion

  • Individuals with Hb ≤ 7 mg/dL who are symptomatic:
    • Dizzy
    • Weak
    • Short of breath
    • Chest pain
    • Syncope
    • Hypotension
  • Postoperative individuals:
    • Hemodynamically stable individuals: Hb ≤ 8 g/dL
    • Presence of symptoms of inadequate oxygen delivery: 
      • Chest pain of cardiac origin 
      • Orthostatic hypotension 
      • Tachycardia unresponsive to fluid resuscitation
  • Critically ill individuals:
    • Hb ≤ 7 mg/dL 
    • Evidence of tissue hypoxia:
      • Central venous oxygen saturation: < 70%
      • Mixed venous oxygen saturation: < 65% 
      • Lactate concentration: > 4 mmol/L
  • In individuals with acute coronary syndrome, Hb should be maintained at > 8–9 g/dL.
  • In individuals with traumatic brain injury, the target Hb should be 7–9 g/dL.
  • These rules do not apply to individuals with active bleeding.

Indications for transfusion of plasma products

  • INR > 1.6 and:
    • Inherited deficiency of anticoagulant factor II, V, X, or XI
    • Prophylactically in individuals on anticoagulant therapy before a procedure 
    • Active bleeding
  • Emergent reversal of warfarin
  • Acute DIC
  • Microvascular bleeding during massive transfusion (1:1:1 rule):
    • 1 unit of plasma
    • 1 unit of platelets
    • 1 unit of RBCs
  • Hereditary angioedema: when C1 esterase inhibitor unavailable
  • Thrombotic microangiopathy: in combination with plasma exchange

Indications for transfusion of platelets

  • Platelets:
    • < 50,000/μL: major surgery or invasive procedure, no active bleeding
    • < 100,000/μL: ocular surgery or neurosurgery, no active bleeding
    • < 20,000/μL: preparation for central line insertion or lumbar puncture
    • < 80,000/μL: preparation for epidural anesthesia
    • < 10,000/μL: prophylactically even in asymptomatic individuals

Indications for transfusion of cryoprecipitate

  • Hemorrhage after cardiac surgery
  • Massive hemorrhage or transfusion 
  • Surgical bleeding
  • DIC
  • Fibrinogen disorders associated with low or dysfunctional fibrinogen
  • Uremic bleeding
  • Bleeding in individuals with liver disease

References

  1. Joint United Kingdom (UK) Blood Transfusion and Tissue Transplantation Services Professional Advisory Committee. (2014). Blood donation. Retrieved July 16, 2021, from http://www.transfusionguidelines.org/transfusion-handbook/3-providing-safe-blood/3-1-blood-donation
  2. Sharma, S., Sharma, P., Tyler, L.N. (2011). Transfusion of blood and blood products: indications and complications. Am Fam Physician 83:719–724. https://pubmed.ncbi.nlm.nih.gov/21404983/
  3. Silbergleid, A.J. (2021). Clinical use of plasma components. UpToDate. Retrieved July 16, 2021, from https://www.uptodate.com/contents/clinical-use-of-plasma-components
  4. Tobian, A. (2021). Clinical use of cryoprecipitate. UpToDate. Retrieved July 15, 2021, from https://www.uptodate.com/contents/clinical-use-of-cryoprecipitate
  5. Yaddanapudi, S., Yaddanapudi, L.N. (2014). Indications for blood and blood product transfusion. Indian J Anaesth 58:538–542. https://pubmed.ncbi.nlm.nih.gov/25535414/
  6. Yuan, S., Goldfinger, D. (2021). Platelet transfusion: indications, ordering, and associated risks. UpToDate. Retrieved July 15, 2021, from https://www.uptodate.com/contents/platelet-transfusion-indications-ordering-and-associated-risks
  7. Thiagarajam, P. (2020). Platelet disorders: overview of platelet disorders. Emedicine. Retrieved August 5, 2021, from https://emedicine.medscape.com/article/201722-overview

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