- 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
- Human T-cell lymphotropic virus (HTLV)
- Donations are ABO and Rhesus factor (Rh) typed and screened.
- Types of blood products used:
- Whole blood
- Packed RBCs
|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–|
|AB–||AB+, AB–||AB–, A–, B–, O–|
- 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%
- Each unit contains:
- Additional processing to RBCs:
- Filtered to remove 85%–90% of WBCs
- ↓ Risk of adverse reactions
- Prepared by exposing the unit to 2500 cGy of radiation
- Inactivates donor T cells
- ↓ Risk of a graft-versus-host reaction in recipient
- Washing RBCs with 0.9% NaCl depletes packed RBCs of most plasma
- Used for individuals with history of severe allergy to transfusion
- 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.
- ↓ Cost
- Ease of collection
- 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 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:
- Blood clotting factors (for hemophilia)
- IV immunoglobulin (IVIG)
- 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.
- 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
|Blood components||Subcomponents of the blood||Type||Production site||Main tasks|
|Plasma 43%–63%||Water 92%||Liquid||Absorbed in GI tract or made during metabolism||Transport medium|
|Plasma proteins 7%||Albumin 54%–60%||Liver|
|Globulins 35%–38%||Alpha globulins: liver||Transport and maintain osmotic concentration|
|Beta globulins: liver||Transport and maintain osmotic concentration|
|Gamma globulins (immunoglobulins): plasma cells||Immune response|
|Fibrinogen 4%–7%||Liver||Blood clotting during hemostasis|
|Regulatory proteins < 1%||Various locations||Regulate various body functions|
|Other dissolved substances 1%||Many different functions|
|Formed elements 37%–54%||Erythrocytes 99%||Erythrocytes||Red marrow||Transports gases, O2 and some CO2|
|Red marrow||Nonspecific immune response|
|Lymphocytes: bone marrow and lymphoid tissue||Lymphocytes: specific immune response|
|Monocytes: red marrow||Monocytes: nonspecific immune response|
|Platelets < 1%||—||Megakaryocytes: red marrow||Hemostasis|
Indications for Transfusion of Blood Products
Indications for RBC transfusion
- Individuals with Hb ≤ 7 mg/dL who are symptomatic:
- Short of breath
- Chest pain
- 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
- < 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
- Fibrinogen disorders associated with low or dysfunctional fibrinogen
- Uremic bleeding
- Bleeding in individuals with liver disease
- 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
- 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/
- 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
- Tobian, A. (2021). Clinical use of cryoprecipitate. UpToDate. Retrieved July 15, 2021, from https://www.uptodate.com/contents/clinical-use-of-cryoprecipitate
- 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/
- 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
- Thiagarajam, P. (2020). Platelet disorders: overview of platelet disorders. Emedicine. Retrieved August 5, 2021, from https://emedicine.medscape.com/article/201722-overview