Transfusion Medicine

Red Blood Cell Transfusion

• RBCs are collected from whole blood donation or by apheresis

  • How RBC apheresis works:

    • Venous access → blood enters the apheresis machine → Blood is separated by centrifugation → a predetermined amount of RBCs are collected and remaining components are returned

    • Why use apheresis?

      • Collects two units of RBCs from one donor in a singe session

      • Reduces the recipient's exposure to multiple donors.

      • Indications:

      • Patients requiring chronic transfusion (Sickle cell disease, thalassemia)

      • Collection of rare blood types

      • O-negative donor collection

• Packed RBCs in preservative solution allow up to 42 days (6 weeks) of refrigerated storage (1-6 °C)

  • Up to 28 days (4 weeks) for irradiated units

• Most RBCs in US are leukocyte reduced.

• One unit of RBCs raises hemoglobin by roughly 1 g/dL (Hct by ~3%) in a stable adult.

• Transfusion indications:

  • Hb <7 g/dL for most hemodynamically stable hospitalized adults

  • Hb <8 g/dL for preexisting cardiovascular disease and orthopedic surgery

  • Active/massive bleeding

    • Hb alone should not drive transfusion.

    • Transfuse hypotensive patients before Hb reaches 7.

  • Symptomatic anemia

Platelet Transfusion

• Mostly collected by apheresis

• Stored at 20–24 °C with continuous gentle agitation for 5 days

  • Irradiation does not change storage life (unlike RBCs)

• Apheresis donation causes citrate-induced hypocalcemia (perioral tingling, cramping)

• In general, spontaneous bleeding is uncommon until platelet count falls below 5,000-10,000

• Thresholds for platelet transfusion based on 2025 AABB guideline:

  • Hypoproliferative thrombocytopenia (chemotherapy, HSCT) in non-bleeding patients: <10,000

  • Central venous catheter placement: <10,000

  • Lumbar puncture: <20,000

  • Consumptive thrombocytopenia without major bleeding: <10,000

  • Interventional radiology procedures:

    • Low risk procedures: <20,000

    • High risk procedures: <50,000

  • Neurosurgery: <100,000

• Platelet transfusion is NOT recommended for:

  • Consumptive thrombocytopenia due to dengue without major bleeding

  • Hypoproliferative thrombocytopenia in nonbleeding adults undergoing autologous HSCT or with aplastic anemia

  • Nonthrombocytopenic patients undergoing cardiovascular surgery (including those receiving cardiopulmonary bypass) in the absence of major hemorrhage

  • TTP/HIT

    • May increase thrombotic complications

    • Reserve for life-threatening bleeding or urgent procedures

  • ITP

    • Usually ineffective if not being treated with steroids/IVIG, because transfused platelets are rapidly destroyed

    • Reserve for life-threatening bleeding or urgent procedures

  • Uremic platelet dysfunction:

    • Platelet transfusion does not help because the transfused platelets acquire the same defect.

    • Treatment:

      • Dialysis clears uremic toxins

      • DDAVP 0.3 µg/kg IV/SC works within ~30 min for 6-8 hours

        • DDAVP may cause tachyphylaxis, hyponatremia with repeat dosing, flushing/hypotension

      • Cryoprecipitate

    • Correction of anemia with ESA/RBC shorten bleeding time.

• Refractory to platelet transfusion?

  • Definition: Corrected Count Increment (CCI) <5,000/μL at 1 h after fresh ABO-identical platelets on at least two consecutive transfusions

    • A raw "before" and "after" platelet counts can look small because the patient is large or the unit contained few platelets. CCI adjusts for body surface area (BSA) and the number of platelets given, so it reflects the true response.

  • Consult transfusion medicine

  • Approach based on the response:

    • If poor rise at 1 hour:

      • Platelets are destroyed almost immediately → antibodies/ immune causes (<20%)

        • Test for HLA antibodies. If positive, give HLA-matched apheresis platelets or give antigen-negative units selected to avoid the patient's antibodies. If still refractory despite good HLA matching, test for HPA (platelet-specific) antibodies.

        • Salvage options: epitope-matched platelets, rituximab, high-dose IVIG, or plasmapheresis.

    • If good rise at 1 hour, then a drop by the next day:

      • Platelets survived initially but were used up or trapped → consumption or splenic sequestration/ non-immune causes (>80%) such as sepsis, splenomegaly, DIC, GVHD

Plasma Transfusion

• Collected from apheresis/whole blood donations

• Contains all clotting factors

• Can be stored at -18C for up to 1 year

• Indicated if patient has multiple factor deficiencies + active bleeding

  • Massive hemorrhage/ massive transfusion

  • Liver disease/acute liver failure with active bleeding

  • DIC

    • If patient has actively bleeding or require an invasive procedure

  • TTP

    • Plasma is used as the replacement fluid during therapeutic plasma exchange.

    • This replaces ADAMTS13 while plasma exchange removes the pathogenic autoantibody and ultra-large VWF multimers.

  • Urgent warfarin reversal if 4-factor PCC is unavailable

    • 4-factor PCC + IV vitamin K is generally preferred for major/life-threatening bleeding because PCC is faster and requires much less volume.

• Plasma compatibility is essentially the reverse of RBC compatibility, because we are worried about the antibodies in the donor plasma attacking the recipient's RBCs.

  • AB blood type = universal plasma donor

  • Rh matching is generally not required for plasma, because plasma contains essentially no clinically meaningful quantity of RBCs.

• Do NOT routinely give plasma for:

  • Volume expansion

    • Use crystalloid/other appropriate fluids.

  • Hypoalbuminemia

  • Nutritional support

  • Mildly elevated INR without bleeding

    • INR of plasma is around 1.1 to 1.4

  • Routine correction of abnormal coagulation tests before a low-bleeding-risk procedure

  • Warfarin reversal when 4-factor PCC is available and indicated

  
  

Cryoprecipitate Transfusion

• Storage:

  • Stored frozen at ≤ −18°C for up to 1 year

  • After thawing, stored at room temperature

  • Must be transfused within 6 hours of thawing

  • Cannot be refrozen.

• Contains:

  • Fibrinogen (factor I)

  • Factor VIII

  • Factor XIII

  • vWF

  • Fibronectin

• Indications:

  • Hypofibrinogenemia/dysfibrinogenemia with bleeding or high bleeding risk

    • Fibrinogen level:

      • <100 mg/dL: commonly used threshold before an invasive procedure

      • <150 mg/dL: consider replacement with active bleeding

      • <200 mg/dL: may be targeted in life-threatening/massive hemorrhage

  • Factor XIII deficiency if factor XIII concentrate is unavailable

  • Fibrinogen replacement in settings such as DIC or massive hemorrhage when fibrinogen is low

IN PROGRESS...