A physician and Consultant in Transfusion Medicine at a hospital in London wonders if colleagues of the e-network would comment on the status of automated red cell exchanges (ARBCx) as a treatment modality in sickle cell disease (e.g. for stroke prevention). He would like feedback on whether ARBCx is preferred to manual exchanges and "top-up" transfusions in the USA. At his hospital, they use regular (every 6-8 weeks) ARBCx for adult sickle cell patients with frequent pain crises, episodes of priapism, non-healing leg ulcers etc, but also in some thalassemia major patients. In the latter group, ARBCx with increase of hemoglobin to around 14 g/dL seems to improve quality of life, and iron overload control is much easier to achieve. The UK physician has not seen adverse effects yet.

In response to the above, the following replies were submitted.

1. A transfusion medicine physician in Texas reports that his group performs ARBCx using the Cobe Spectra on 3 adults and 13 pediatric patients on a regular basis for prevention of second stroke. They never perform manual exchange for SCD. When the patient is too small to tolerate ARBCx (venous access problem), the patient is started on a hypertransfusion protocol. Once the patient has adequate venous access, they are placed on ARBCx. After tolerating a few standard RBC exchanges, they put the patient on isovolemic hemodilution (IHD) followed by red cell exchange protocol (presented at ASFA May, 2002). With IHD-RBCx the Texas group is able to increase the interval between two treatments from 4-5 weeks to 7-8 weeks. Also the Texas group has observed their patients require approximately 1 unit of blood less during each procedure as compared to standard RBCx. The Texas group is gradually increasing the patient Hct to around 30-32% over a year.

2. A hematologist in Los Angeles cautions that when transfusing patients with SCD to a hemoglobin level of 14g/dL, there is a risk for the onset of the hyper-viscosity syndrome.

ADDENDA Nov. 7, 2002

3. A clinical hematologist in Philadelphia reports that at his hospital, his group has a large experience with automated erythrocytapheresis in sickle cell disease, mostly pediatric patients, but some adults, including patients who have been maintained free of recurrent stroke and free of transfusional iron overload for over 10 years. They are currently using automated erythrocytapheresis in an increasing number of patients for primary stroke prevention. They use isovolemic hemodilution in most of these patients to increase the efficiency of the exchange. They would not routinely raise the ending hemoglobin level as high as 14 gm/dL. The hematologist is not sure what the advantage of manual exchanges would be except if one did not have access to automated cell separators, or if the patient is so small that use of the automated cell separator is not feasible. In the youngest patients with sickle cell disease who need chronic transfusion therapy, they would usually support the patient on simple transfusions until they were big enough to switch to erythrocytapheresis.

ADDENDA Nov. 8, 2002

4. The inquiring physician and Consultant in Transfusion Medicine at a hospital in London wishes to clarify his statement about raising the haemoglobin to 14g/dL with automated red cell exchange. This pertains to exchanges in patients with thalassemia major, not sickle cell disease.

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Ira A. Shulman, MD
CBBS e-Network Forum Editor & Moderator