From the Guidelines
Red blood cell exchange transfusions for chronic programs should be performed every 3 to 6 weeks, with the exact timing adjusted based on pre-procedure hemoglobin S (HbS) levels, as recommended by the American Society of Hematology 2020 guidelines for sickle cell disease: transfusion support 1. The goal of these exchanges is to maintain HbS levels below a target threshold to reduce sickle cell disease-related complications. Before each scheduled exchange, HbS levels should be measured to determine if the procedure is needed or if the interval should be adjusted. If HbS levels rise too quickly between exchanges, the interval may need to be shortened; conversely, if levels remain well-controlled, the interval might be extended. Each exchange typically replaces 1-1.5 times the patient's blood volume with donor red blood cells, which helps prevent vaso-occlusive crises, stroke, acute chest syndrome, and other sickle cell complications while minimizing iron overload compared to simple transfusions 1. Patients should be monitored for transfusion reactions, alloimmunization, and iron status throughout the chronic exchange program. The procedure is typically performed in specialized centers with experience in apheresis and sickle cell disease management, and consultation with a hematologist and transfusion medicine specialist is advised to assess safety for the individual patient and technical specifications 1. Key considerations include the choice between red cell exchange with isovolemic hemodilution (IHD-RCE) or conventional RCE, with the American Society of Hematology guideline panel suggesting either method for patients with SCD receiving chronic transfusions, based on very low certainty in the evidence about effects 1. Ultimately, the decision on the timing and method of red blood cell exchange transfusions should be individualized based on patient-specific factors and institutional resources, with a focus on minimizing morbidity, mortality, and improving quality of life.
From the Research
Exchange Frequency
- Exchanges are typically performed every 3-6 weeks in chronic programs, with adjustments made based on pre-procedure HbS levels 2.
Indications for Red Blood Cell Exchange
- Red blood cell exchange is indicated to prevent or treat complications arising from the presence of HbS, with goals of reducing HbS levels and preventing hyperviscosity 3.
- The target HbS level is generally desirable in the range of 30% 3.
Management of Sickle Cell Disease
- Transfusion therapy is a cornerstone in the management of sickle cell disease, significantly reducing morbidity and mortality 4.
- Red blood cell exchange can be performed by manual or automated exchange, each with its own set of advantages and disadvantages 4.
Blood Transfusion in Sickle Cell Disease
- Blood transfusion should be aimed at increasing tissue delivery of oxygen, with Hb S being a low affinity Hb that delivers oxygen at a lower partial pressure of oxygen compared to Hb A 5.
- Chronic transfusion protocols are implemented in cases of strokes or high cerebral blood flow ultrasonic studies as a prophylactic measure 5.