Apheresis, Blood Administration, and Patient Blood Management

Apheresis withdraws blood, separates a target component, diverts or collects it, and returns the remainder. Centrifugation separates by density: red cells (RBCs) pack outward first, then white cells (WBCs) and platelets, then plasma. Two flow patterns cover most instruments. Intermittent-flow centrifugation processes one bowl of blood at a time: whole blood enters through a central inlet tube to the base of the spinning bowl, and as the bowl fills the lighter layers overflow in sequence through the outlet in the bowl head, plasma first and then the platelet-rich layer. A valve diverts the target component to its collection bag. The centrifuge then stops and the retained bowl contents are reinfused before the next cycle begins. Cycles are repeated until the target yield is reached, typically 6 to 8 cycles for a plateletpheresis procedure. Single-needle access is common and suits donors. The extracorporeal volume is typically higher than in continuous-flow systems. Continuous-flow centrifugation draws, separates, and reinfuses simultaneously: blood enters one end of a separation channel, the layers form along its length, and the target layer leaves through its own port while the remaining layers return. Access is usually through two access lines (two venous sites or a dual-lumen central catheter), and some systems support single-needle operation. The extracorporeal volume is typically lower. Membrane plasma separation passes plasma through membrane pores that retain the cellular components, producing cell-free plasma for collection or exchange.^{11 Bloch EM, et al. Technical Manual. 2026.}

Citrate is the standard apheresis anticoagulant, metered into the draw line as blood leaves the access needle. It chelates ionized calcium and halts the calcium-dependent coagulation steps inside the circuit. Citrate metabolism returns calcium to the circulation, and parathyroid hormone responds to any ionized-calcium dip by mobilizing bone calcium and increasing intestinal absorption and renal reabsorption. When citrate delivery outpaces that response, perioral or distal paresthesia appears, and severe reduction progresses to tetany and arrhythmia. Fluid that shifts into the circuit can produce hypovolemic hypotension. The extracorporeal volume of an apheresis procedure is generally kept at or below 15% of estimated total blood volume under the device's validated limits and the facility procedure. The 10.5 mL/kg collection limit is a separate rule that applies to whole-blood donation. A distinct vasovagal reaction produces parasympathetic bradycardia and hypotension, most often in younger patients, and remains a recognized event during therapeutic procedures as well as donations.^{11 Bloch EM, et al. Technical Manual. 2026.}

Donor-side apheresis, including donation intervals, yields, and donor-reaction management, is covered in the Donor Qualification, Collection, and Reactions lesson.

Therapeutic apheresis removes a pathogenic constituent more efficiently than the body's clearance mechanisms can. Procedures divide by target: cytapheresis selectively removes red cells, white cells, or platelets, and plasmapheresis or plasma exchange removes plasma when the pathologic substance circulates there. The American Society for Apheresis (ASFA) assigns each disease, indication, and modality a category: category I means apheresis is accepted as first-line therapy, category II accepts it as second-line therapy, category III leaves the optimum role undefined and individualized, and category IV applies when evidence shows apheresis is ineffective or harmful, with institutional-review-board approval desirable before any use.^{22 Connelly-Smith L, et al. Guidelines on the use of therapeutic apheresis in clinical… 2023.}

The blood bank medical director provides transfusion-medicine consultation. Responsibility is divided in writing. The treating clinician is responsible for the diagnosis, indication, vascular access, and overall care. The apheresis team verifies the order and ASFA category and controls the procedure, anticoagulation, replacement fluid, and laboratory monitoring under that plan. Written informed consent is required.^{11 Bloch EM, et al. Technical Manual. 2026.}

Therapeutic plateletpheresis may be ordered for symptomatic thrombocytosis, often when the platelet count exceeds 1,000,000/µL with thrombosis or hemorrhage. The laboratory reports the preprocedure and postprocedure counts. A session commonly lowers the count by 30% to 60%.^{11 Bloch EM, et al. Technical Manual. 2026.}

Therapeutic leukapheresis may be ordered for hyperleukocytosis with concern for leukostasis, often at a white-cell or blast count above 100,000/µL. Leukostasis occurs more often in acute myeloid leukemia than in acute lymphoblastic leukemia. Preprocedure and postprocedure counts document a reduction that is commonly 30% to 60% per session.^{11 Bloch EM, et al. Technical Manual. 2026.}

Erythrocytapheresis (red-cell exchange) replaces the patient's red cells with donor cells while holding the volume constant. For sickle cell disease, the transfusion service selects compatible red cells that are relatively fresh, under 10 days old, leukoreduced, Hb S-negative, and matched for Rh and K antigens. The apheresis service measures the preprocedure and postprocedure Hb S fraction against the ordered target, often below 30% during an acute complication.^{1,31 Bloch EM, et al. Technical Manual. 2026.3 Association for the Advancement of Blood &…, et al. Circular of Information for the Use of Human Blood and Blood… 2024.} CDC does not recommend exchange transfusion for severe malaria because benefit has not been demonstrated.^{44 Centers for Disease Control and Prevention. Treatment of severe malaria. 2026.} Red-cell exchange may be considered by the clinical and transfusion medicine services for selected severe babesiosis cases or after an ABO-mismatched red-cell transfusion. The clinical service determines the indication. The transfusion and apheresis services document the implicated cells, replacement component, procedure yield, and postprocedure result.

Hematopoietic progenitor cell collection harvests CD34-positive mononuclear cells from the buffy-coat layer after growth-factor mobilization, sparing the patient a marrow harvest under anesthesia. Photopheresis treats leukapheresis-collected leukocytes with 8-methoxypsoralen and UVA light, which crosslinks DNA and induces apoptosis. It is FDA-approved for cutaneous T-cell lymphoma with additional use in graft-versus-host disease and solid-organ transplant rejection.^{11 Bloch EM, et al. Technical Manual. 2026.}

Plasma exchange removes the patient's plasma and replaces it with albumin, plasma, or a combination. Thrombotic thrombocytopenic purpura is the classic category I indication, and the transfusion service supplies the plasma for it. Those plasma components carry the same transfusion-reaction risks described in the Transfusion Reactions and Transfusion-Transmitted Infections lesson. Immunoadsorption perfuses separated plasma through a ligand-coated column, historically staphylococcal protein A, that binds IgG and immune complexes and removes pathogenic antibody without any replacement fluid.^{11 Bloch EM, et al. Technical Manual. 2026.}

The procedure order specifies the replacement fluid. The apheresis service verifies it and monitors coagulation. Albumin is the standard oncotic replacement because it carries no antibody, needs no compatibility testing, and carries minimal infection risk under modern viral inactivation. Fatal apheresis events are rare and mostly cardiac or respiratory. They disproportionately involve plasma as the replacement fluid. This pattern supports albumin for routine oncotic replacement. Plasma is used when the ordered indication or the coagulation results call for it.^{11 Bloch EM, et al. Technical Manual. 2026.}

Apheresis complications overlap with donor-collection physiology. Citrate toxicity and hypocalcemia lead the list, with the signs and the parathyroid response described above. Oral or intravenous calcium follows the facility procedure under medical direction. Vascular-access complications include hematoma, infection, and pneumothorax after central-line placement. Vasovagal reactions and hypovolemia follow, the latter more frequent with intermittent-flow instruments. Allergic reactions occur, most often to plasma replacement and occasionally to albumin. Mechanical hemolysis follows equipment malfunction such as a kinked line. Air embolism is rare. Repeated plasma removal depletes clotting factors and immunoglobulins. Report coagulation results before and after each exchange, because they guide whether plasma must replace part of the albumin volume.^{11 Bloch EM, et al. Technical Manual. 2026.}

Positive identification is repeated at every stage: at collection, in the laboratory during testing and again at issue, and at the bedside immediately before infusion, as detailed in the Pretransfusion Testing lesson. Clerical error at the bedside remains the leading preventable cause of fatal ABO-incompatible transfusion, which is why the final check matches the recipient, the unit label, and the compatibility record together.^{1,31 Bloch EM, et al. Technical Manual. 2026.3 Association for the Advancement of Blood &…, et al. Circular of Information for the Use of Human Blood and Blood… 2024.}

Every component is administered through a sterile, pyrogen-free filter that removes clots and aggregates, generally a standard 150- to 260-micron filter. The infusion starts slowly, with the patient observed for the first 10 to 15 minutes, and then runs as rapidly as tolerated. It finishes within 4 hours after the container is entered, because room-temperature storage beyond that increases the risk of bacterial growth. When the rate must stay slow, the transfusion service issues smaller aliquots. Pulse, respiration, blood pressure, and temperature are monitored periodically throughout.^{33 Association for the Advancement of Blood &…, et al. Circular of Information for the Use of Human Blood and Blood… 2024.}

Hemoglobin, platelet count, and INR results near a threshold support the transfusion decision. Transfusion thresholds pair a laboratory value with the clinical setting. For most hemodynamically stable hospitalized adults, the 2023 AABB international guideline recommends a restrictive red-cell threshold of 7 g/dL. The same guideline allows 7.5 g/dL for cardiac surgery and 8 g/dL for orthopedic surgery or preexisting cardiovascular disease. For hospitalized adults with acute myocardial infarction, the 2025 guideline suggests a liberal strategy below 10 g/dL on low-certainty evidence.^{5,65 Carson JL, et al. Red blood cell transfusion. 2023.6 Pagano MB, et al. Red cell transfusion in acute myocardial infarction. 2025.} Platelet thresholds follow the population-specific recommendations in the component therapy lesson: prophylaxis below 10,000/µL for nonbleeding hypoproliferative thrombocytopenia during chemotherapy or allogeneic transplantation, no routine prophylaxis in the guideline's autologous-transplant and aplastic-anemia groups, and bleeding support at higher counts. Plasma is considered for active bleeding with PT or activated partial thromboplastin time (APTT) elevation or an INR above 1.5, and cryoprecipitate for fibrinogen or factor XIII deficiency. The Circular of Information states that plasma should not be given for a minimally elevated INR of 1.7 or less in a nonbleeding patient, because roughly 30% factor activity remains and a standard dose may leave the INR unchanged.^{33 Association for the Advancement of Blood &…, et al. Circular of Information for the Use of Human Blood and Blood… 2024.}

Patient blood management uses patient-specific laboratory and clinical data to reduce avoidable transfusion. The laboratory reports blood counts, iron studies, coagulation results, and trends that identify anemia or hemostatic abnormalities before a procedure. The clinical service decides whether iron replacement, erythropoietic support, medication changes, or intraoperative blood conservation is appropriate. The transfusion service uses facility guidelines and audit data to assess whether each transfusion had a documented indication. Report the trend with each result, because the clinical service considers the trend along with any single value near a threshold.^{11 Bloch EM, et al. Technical Manual. 2026.}