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432 Part V: Therapeutic Principles Chapter 28: Therapeutic Apheresis: Indications, Efficacy, and Complications 433

in the management of acute multiorgan failure syndrome, preparation useful when circumstances require isovolemic procedures. The vol-
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for general anesthesia, complications of pregnancy, or frequent pain ume of red cells to be removed (VR) during an automated erythrocy-
episodes. 48,56 tapheresis procedure in order to achieve a desired hematocrit can be
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calculated as :
Red Cell Exchange in Protozoan Disease
Chapter 53 discusses infections with microorganisms in greater detail. VR = (startinghematocrit-desiredhematocrit)
Malaria The World Health Organization has suggested that 79
exchange transfusion be considered for nonimmune (i.e., not previously × [blood volume(ml/kg)] × [bodyweight(kg)]
exposed) patients with falciparum malaria who have any of the follow-
ing characteristics: greater than 30 percent parasitemia in the absence of This formula also estimates the volume of replacement fluid (colloid or
clinical complications, greater than 10 percent parasitemia in the pres- crystalloid) needed to maintain isovolemic fluid balance. 83
ence of severe disease, greater than 10 percent parasitemia and failure
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to respond to optimal chemotherapy after 12 to 24 hours, or greater than Polycythemia Vera
10 percent parasitemia and poor prognostic factors (elderly, late-stage Chapter 84 provides a more detailed discussion.
parasites [schizonts] in the blood). The Centers for Disease Control A retrospective case series described 69 patients with polycythe-
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and Prevention (CDC) previously recommended strong consideration of mia vera who underwent 206 isovolemic erythrocytapheresis proce-
exchange transfusion or red cell exchange in severely affected patients. dures using 4 percent albumin as replacement fluid. 83,85 Hematocrit was
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Subsequently, the CDC has rescinded this recommendation based on reduced from 56.8 ± 5.6 percent to 41.9 ± 6.6 percent after removal of
a literature review and an analysis of the U.S. national malaria surveil- 1410 ± 418 mL of red blood cells with a hematocrit of 79.7 ± 9.3 percent.
lance system (patients reported 1985 to 2010) that found no evidence for Close followup data were provided for a subset of 21 patients whose
efficacy of exchange transfusion as adjunctive therapy in severe malaria hematocrits were reduced from 58 ± 5.7 percent to 41.5 ± 4.9 percent by
when rapidly acting antimalarials (specifically artemisinins) were avail- a single erythrocytapheresis procedure and were maintained at less than
able. It is not certain whether the emergence of artemisinin-resistant 50 percent for a median of 6 months. The durability of response to a
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Plasmodium falciparum will affect their position. 66–68 single procedure was associated with a median 70 percent inhibition
Babesiosis Infection with intraerythrocytic protozoan Babesia of in vitro erythropoietin-independent burst-forming unit–erythroid
microti is most commonly acquired through the bite of the tick Ixo- (BFU-E) growth that the authors attributed to iron removal during the
des scapularis and presents with clinical manifestations that range from apheresis procedure. This claim has not been confirmed. Automated
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asymptomatic infection or influenza-like illness to organ failure and erythrocytapheresis may be useful in polycythemia vera for the rapid
death. Complications may include acute respiratory distress syndrome induction of hematocrit lowering, followed by maintenance therapeutic
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(ARDS), disseminated intravascular coagulopathy, renal failure, or phlebotomy, for emergent isovolemic hematocrit lowering in patients
hemolytic anemia. Immunocompromised, elderly, or asplenic individ- with acute thrombotic or microvascular complications, or to avoid
uals are most at risk for severe manifestations. 70,71 Between 2009 and perioperative thrombohemorrhagic complications in a patient with an
2013 babesiosis was the most frequent cause of transfusion-transmitted uncontrolled hematocrit who requires urgent surgery. 56,85
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infectious death reported to the FDA. In the United States, the occur-
rence of babesiosis in Connecticut, Massachusetts, Minnesota, New Jersey,
New York, Rhode Island, and Wisconsin accounted for 97 percent of Hereditary Hemochromatosis
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1124 cases of babesiosis reported to the CDC in 2011. Because the par- Chapter 43 provides a more detailed discussion.
asite is completely intraerythrocytic, and, despite the lack of clinical tri- Early observational studies from Europe 87–91 suggested that auto-
als, observational evidence indicates that the parasite can be efficiently mated erythrocytapheresis could deplete iron from patients with
removed using automated red cell exchange. Red cell exchange is hereditary hemochromatosis more efficiently and quickly than could
4,74
recommended for patients with severe manifestations, high parasite conventional therapeutic phlebotomy. A prospective, randomized
4
burdens (>10 percent) or who are at high risk. trial from the Netherlands involving 38 patients with newly diagnosed
C282Y-homozygous hemochromatosis compared automated erythro-
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Miscellaneous Uses of Red Cell Exchange cytapheresis to conventional therapeutic phlebotomy. Study subjects
Red cell exchange has been successfully used, in conjunction with Rh were evenly randomized to either treatment arm. The primary out-
immunoglobulin, to prevent Rh sensitization of an Rh-negative woman come measure was the number of procedures needed to reach a serum
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who received emergency transfusion with Rh-positive red blood cells. ferritin target of 50 mcg/L or less. This was reached in a mean (range)
The macrolide immunosuppressant tacrolimus is highly erythrocyte-bound of nine (4 to 20) procedures over 19.6 (7 to 37) weeks in the erythrocy-
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and overdoses are not responsive to plasma exchange, but can be miti- tapheresis arm and 27 (11 to 58) procedures over 33.7 (12 to 79) weeks
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gated using red cell exchange. Red cell exchange can successfully treat in the phlebotomy arm. Erythrocytapheresis removed 427 (294 to 545)
refractory methemoglobinemia in patients with glucose-6-phosphate mg of iron with each procedure compared to 205 (136 to 230) mg with
dehydrogenase deficiency or after ingestion of strong oxidants. 78 each phlebotomy. Secondary outcomes were total duration of treat-
ment, side effects, change in iron status and liver function, quality of
life (related to health) and costs. Adverse effects, including hypocalce-
RED BLOOD CELL DEPLETION mia, vasovagal syncope, and mild dizziness, occurred in 3 of 19 patients
in the erythrocytapheresis group and in 5 of 19 patients in the phlebot-
(ERYTHROCYTAPHERESIS) omy group. The 3.5-fold higher cost of performing erythrocytapheresis
Although therapeutic phlebotomy is a mainstay of management of versus therapeutic phlebotomy was fully counterbalanced by greater
polycythemia vera and hereditary hemochromatosis, 79–82 ASFA now time off from work and lost productivity among the phlebotomy group.
considers these clinical entities to be category I (first-line) indications The investigators were careful to point out that the cost structure of
for automated erythrocytapheresis. The role of automated erythrocy- apheresis treatments versus phlebotomy in the Netherlands may not
4
tapheresis in secondary erythrocytosis is less certain, but it may be apply to other countries.
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