Chapter 95: 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 95–1 contains the principal applications of the technique.

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

• Adverse effects are infrequent and mild; they are hypotension, urticaria, and hypocalcemia.

• Cytapheresis refers to removal or exchange of a blood cell element (eg, leukapheresis, plateletpheresis, erythrocytapheresis).

• Plasmapheresis refers to removal or exchange of plasma.

PLATELETPHERESIS

• Thrombocythemia or extreme thrombocytosis can almost always be managed pharmacologically.

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

• If plateletpheresis is required in patients with thrombocythemia requiring urgent platelet reduction, pharmacologic therapy should be administered simultaneously for long-term control (see Chap. 43).

• Reduction in the platelet count of about 50% 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 greater than 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 (see Chaps. 46 and 47).

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

• Therapeutic leukapheresis may be used in lieu of chemotherapy to treat CML (eg, 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%.

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

• Photopheresis, also known as 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 the patient (see Chap. 66).

• Leukapheresis can be used to harvest ...