Transfusion medicine

Transfusion therapy

Red blood cell use


Editorial Board Member: Kyle Annen, D.O.
Deputy Editor-in-Chief: Patricia Tsang, M.D., M.B.A.
Philip Crispin, M.B.B.S.

Topic Completed: 9 March 2021

Minor changes: 11 May 2021

Copyright: 2020-2021, PathologyOutlines.com, Inc.

PubMed Search: Red blood cell use[TIAB]

Philip Crispin, M.B.B.S.
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Cite this page: Crispin P. Red blood cell use. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/transfusionmedredbloodcelluse.html. Accessed December 3rd, 2021.
Definition / general
  • Red blood cell (RBC) transfusion is used to improve oxygenation of the tissues to correct symptoms and prevent complications from anemia
Essential features
  • RBC transfusions are used to improve tissue oxygenation in anemia
  • For hemodynamically stable recipients, evidence favors restrictive over liberal RBC transfusion
  • Blood donors are screened by history, observations and blood tests to maintain donor and recipient safety
  • Manufacturing such as irradiation may be used to optimize RBC products for certain recipients
Terminology
  • Packed RBCs (or packed cells): red cells that have been separated from whole blood and have a higher hematocrit
  • Whole blood: blood stored as collected from donors in anticoagulant with all blood constituents
  • Patient blood management refers to systems designed to maximize hemoglobin, prevent blood loss and allow tolerance of anemia and includes restrictive approaches to transfusion
Pathophysiology
  • Main function of RBC transfusion is to improve oxygenation by increasing the oxygen carrying capacity of blood through an increased hemoglobin level
  • RBC transfusion may also increase microvascular flow by increasing blood viscosity
  • RBC transfusion, particularly exchange transfusion, may reduce sickling in sickle cell disease (Blood Adv 2020;4:327)
  • In thalassemia major, adequate RBC transfusion suppresses extramedullary hematopoiesis and allows normal growth and development
Blood donor screening
Blood donor testing (per FDA)
  • Hemoglobin: > 12.5 g/dL (F) or > 13 g/dL (M); > 11 g/dL (autologous)
  • Hepatitis B nucleic acid test, surface antigen and core antibody
  • Hepatitis C antibody and nucleic acid test
  • HIV1 and 2 antibodies and nucleic acid test
  • HTLV1 and 2 antibodies
  • Syphilis (Treponema pallidum) antibodies
  • Trypanosoma cruzi antibodies
  • West Nile virus antibodies seasonally from June 1 to October 31
  • Babesia nucleic acid testing in affected states
  • Zika virus nucleic acid testing is license but inadequate as a screen test; deferral based on contact or travel history
  • CMV seronegative testing is only required if the product is to be CMV negative
Donor deferral
  • Donor deferral may be based on results of screening or donor testing
  • Indefinite - can't donate in the foreseeable future; requalification to donate possible with changes in regulation or guidance (e.g. intravenous drug use has been previously indefinitely deferred but may now requalify providing they meet all current donation criteria)
    • Infections (e.g. with HIV, HBV, HCV, Ebola)
    • Residence or blood transfusion within countries and timeframes at risk of bovine spongiform encephalopathy
  • Temporary - deferred for known periods based on time or risk factor event
    • Recent infection
    • Recent travel to areas endemic for blood borne infections, such as malaria, Ebola
    • Deferral for 3 months for:
      • Male to male sex, sex with a prostitute or someone with (or at risk of) HIV
      • Needlestick injury
      • Transfusion or allogeneic transplant
      • Tattoo or body piercing
      • Travel to malaria endemic areas
    • Deferral for 6 months following Zika virus infection or travel to areas of increased risk of Zika
    • Deferral for 12 months following imprisonment
    • Deferral for 3 years for prior residents (> 5 years) of malaria endemic regions or history of malaria
    • Medications (AABB: Medication Deferral List [Accessed 02 October 2020])
Laboratory
Treatment
  • Typical RBC unit increases hemoglobin by about 1 g/dL in adults
  • For children, 10 mL/kg RBC increases hemoglobin by 2 g/dL(Transfusion 2007;47:212)
  • Restrictive hemoglobin thresholds for RBC transfusion have been proven to be as safe or safer than liberal and provide noninferior outcomes in:
  • No particular transfusion trigger based on hemoglobin or any other parameter has been supported by controlled trials in chronic hypoproliferative anemia; transfusion thresholds are based on levels where there is a demonstrated improvement in symptoms for the individual
  • Many people with hemoglobin levels below 7 g/dL are able to tolerate anemia well and transfusion is not always required, especially when there is a reversible cause, such as iron deficiency
  • Where there is a foreseeable potential need for transfusion, such as elective surgery, optimization of preoperative hemoglobin (consider iron or erythropoiesis stimulating agents as appropriate) is encouraged to reduce transfusion needs
  • Where transfusion is indicated for anemia, best practice is to titrate the transfusion volume to needs by giving a single unit and reassessing clinically
  • RBC may be transfused in sickle cell disease to prevent sickling in acute chest syndrome, during pregnancy or preoperatively
    • Red cell exchange is preferred over simple red cell transfusion for chronic transfusion therapy or where RBC transfusion is otherwise indicated but there is high hemoglobin (Blood Adv 2020;4:327)
Special conditions
  • Leukocyte reduced
    • < 5 x 10⁶ leukocytes per unit
    • Reduce HLA alloimmunization, febrile nonhemolytic transfusion reactions and CMV transmission
  • CMV negative
    • Serologically negative; doesn't exclude donors within window periods
    • Leukocyte depleted have very low to negligible CMV risk
    • Recommended during pregnancy or low birth weight premature neonates
    • May be used in CMV negative transplant recipients or during intensive chemotherapy
  • Irradiated
    • To 25Gy to prevent transfusion associated graft versus host disease (by preventing the proliferation of immunocompetent donor lymphocytes, which can damage host tissue)
    • Indicated for HLA matched or related donors, intrauterine transfusions or neonates who previously received intrauterine transfusions, stem cell transplant recipients or certain immunocompromised groups (Hodgkin lymphoma, after purine analogue therapy, aplastic anemia treated with antithymocyte globulin and some severe T cell immunodeficiency syndromes)
    • GVHD risk is low but potentially fatal; emergency transfusion need not be delayed if irradiated blood is not immediately available
  • Washed
    • Indicated for the removal of plasma proteins associated with severe reactions (e.g. prior anaphylaxis to IgA)
  • Deglycerolized
    • Frozen red cell units stored in glycerol have this removed before transfusion, usually from rare donor phenotypes
    • Red cell loss during processing means units are up to 20% smaller
  • Whole blood
    • Increasing use in trauma / critical bleeding setting to replace all blood components
    • Rarely used outside this setting
  • Reference: AABB: Circular of Information - For the Use of Human Blood and Blood Components [Accessed 26 October 2020]
Sample assessment & plan
  • Assessment: A 27 year old primipara has a post partum hemorrhage following a term vaginal delivery managed with oxytocin and ergometrine. The following day she reports being tired. She has a blood pressure of 115/70 and a pulse rate of 84 bpm. Her hemoglobin is measured at 6.8 g/dL, which is 3 g/dL less than in first trimester when she was noted to be iron deficient.
  • Plan: While there may be a more rapid improvement in symptoms with transfusion, this is very small when compared with intravenous iron therapy and insignificant when compared with allowing time to recover from a traumatic delivery. Iron therapy is more likely to lead to sustained increase in hemoglobin and replenishment of iron stores. Transfusion may be safely withheld; however, if transfusion is prescribed for symptoms, a single unit should be given followed by clinical reassessment (BMC Pregnancy Childbirth 2010;10:83).
Additional references
Board review style question #1
A 64 year old Caucasian woman has hemoglobin of 8.6 g/dL (12 - 15 g/dL), with an MCV of 72 fL (80 - 100 fL) one day after acute myocardial infarction, treated with left anterior descending stent insertion. She is A RhD negative and has an anti-D and an anti-C on red cell antibody screen. She is asymptomatic, has a blood pressure of 120/75 mmHg, a pulse of 68 bpm and no signs of congestive cardiac failure. You are asked to consult on transfusion management. The best advice is to

  1. Advise that alternatives to transfusion should be considered as the multiple antibodies will make it hard to source blood for transfusion
  2. Indicate that transfusion is unlikely to be required based on the clinical features and that further investigation for iron deficiency should be considered
  3. Advise that transfusion should be undertaken with leukocyte depleted blood to prevent further antibody formation
  4. Advise to transfuse 2 units of red cells to bring the hemoglobin up to 10 g/dL and consider the cause for anemia
  5. Supply washed red cells to prevent antibodies reacting with red cells
Board review style answer #1
B. Indicate that transfusion is unlikely to be required based on the clinical features and that further investigation for iron deficiency should be considered. Evidence indicates that transfusion with a Hb > 8 g/dL does not improve outcomes, even after AMI. The red cell indices indicate possible iron deficiency anemia, especially in a population with lower thalassemia prevalence. Best practice would indicate treatment of the underlying iron deficiency rather than transfusion and a search for the cause.

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Reference: Red blood cell use
Board review style question #2
Washed red cells are indicated

  1. To prevent HLA alloimmunization in a 16 year old with acute myeloid leukemia
  2. To prevent a febrile nonhemolytic transfusion reaction in a patient undergoing partial hepatectomy with a history of a similar reaction 2 years prior following their last transfusion
  3. In all people having regular transfusions
  4. In a 57 year old having a total hip replacement with IgA deficiency and a history of anaphylaxis to fresh frozen plasma
  5. In a 36 year old with severe postpartum anemia who had a red cell transfusion stopped due to urticaria and has an IgA of 30 mg/dL (60 - 400)
Board review style answer #2
D. In a 57 year old having a total hip replacement with IgA deficiency and a history of anaphylaxis to fresh frozen plasma. People with IgA deficiency may develop anti-IgA and anaphylaxis to IgA present in all fresh blood products. Washing aims to remove the small amounts of IgA remaining in RBCs.

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Reference: Red blood cell use
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