Chapter 94: Therapeutic Hemapheresis

INTRODUCTION

• Therapeutic apheresis is the application of blood cell separation techniques to treat certain clinical conditions.

• A continuous-flow blood separator is usually used.

• Table 94–1 contains the principal applications of the technique.

• Hemapheresis is usually used in hematologic therapy for acute problems.

• Adverse effects infrequent and mild: hypotension, urticaria, hypocalcemia.

• Cytapheresis refers to removal or exchange of a blood cell element, e.g., leukapheresis, plateletpheresis, erythrocytapheresis.

• Plasmapheresis refers to removal or exchange of plasma.

PLATELETPHERESIS

• Thrombocythemia or extreme thrombocytosis can usually be managed pharmacologically.

• Plateletpheresis is useful for those who need rapid, temporary reduction of the platelet count in emergent conditions (e.g., ongoing thrombosis) or for patients who cannot tolerate drug therapy (e.g., early pregnancy).

• If plateletpheresis is required in patients with thrombocythemia requiring urgent platelet reduction, pharmacologic therapy should be administered simultaneously for long-term control.

• Reduction in the platelet count of about 50 percent may be achieved with each procedure, but the platelet count returns to pretreatment value in a few days.

LEUKAPHERESIS

• Leukostasis may be ameliorated by leukapheresis with rapid cytoreduction in patients with acute myelogenous leukemia whose leukocyte count is greater than 50 to 100 × 10⁹/L; patients with acute lymphocytic leukemia whose leukocyte count is greater than 75 to 100 × 10⁹/L; or patients with chronic myelogenous leukemia (CML) whose leukocyte count is greater than 300 × 10⁹/L, or who have > 50 × 10⁹/L blasts.

• Unfortunately, there are no clearly established thresholds, so that patients with any blast count who have signs of leukostasis should undergo leukapheresis.

• Therapeutic leukapheresis prior to chemotherapy reduces tumor burden and may minimize metabolic abnormalities due to tumor lysis.

• Therapeutic leukapheresis can lower the white cell counts, reduce organomegaly, and reduce tumor burden in chronic lymphocytic leukemia, but cytotoxic therapy is required for disease control.

• Therapeutic leukapheresis may be used in lieu of chemotherapy to treat CML, e.g., in pregnancy, to allow for delay in starting chemotherapy until after the first trimester or longer.

• In acute or chronic leukemia, a single therapeutic leukapheresis will reduce the leukocyte count by 25 to 50 percent.

• The rate of mobilization of cells and the rate of cell proliferation dictate the frequency of therapeutic leukapheresis required to achieve goal.

• Photopheresis, extracorporeal photochemotherapy, can improve erythroderma in cutaneous T-cell lymphoma (Sézary syndrome). Leukocytes removed by cytapheresis are treated with 8-methoxypsoralen and ultraviolet light and returned to patient.

• Leukapheresis can be used to harvest lymphocytes, dendritic cells, or allogeneic or autologous blood stem cells for immunotherapy or stem cell transplantation.