What are the target hematocrit and hemoglobin (Hb) levels after Red Blood Cell (RBC) exchange?

From the Guidelines

The target hematocrit and hemoglobin levels for red blood cell exchange in patients with sickle cell disease should be around 100 g/l to avoid hyperviscosity, with the goal of reducing the HbS% to a target level, which may be less than 30% in high-risk patients. When considering red blood cell exchange, it is essential to balance the need to reduce the percentage of abnormal cells while maintaining adequate oxygen-carrying capacity 1. For patients undergoing high-risk surgery or those with significant comorbidity, an exchange transfusion should be considered to reduce the HbS% to a target level, and the target Hb should be around 100 g/l to avoid hyperviscosity 1. Some key points to consider when determining the target hematocrit and hemoglobin levels for red blood cell exchange include:

• The patient's sickle genotype, age, comorbidities, and type of surgery
• The baseline Hb and the health of the patient
• The bleeding risk associated with the procedure
• The need to reduce the HbS% to a target level, which may be less than 30% in high-risk patients
• The risk of allo-immunisation, which is estimated to occur in 7-30% of patients with sickle cell disease 1. It is crucial to note that these decisions should be guided by an expert in sickle cell disease, and the hospital transfusion laboratory may need to order special blood supplies from the appropriate transfusion service 1. In addition, patients with sickle cell disease are advised to carry a transfusion card that includes information about allo-antibodies and their full red cell phenotype or genotype, and donor red cells should be HbS negative and must be compatible for ABO, Rh, and Kell antigens and for additional known allo-antibodies 1.

From the Research

End Hematocrit and Hemoglobin Targets in Red Blood Cell Exchange

• The target hematocrit (Hct) and hemoglobin (Hb) levels in red blood cell exchange for patients with sickle cell disease vary, but most studies agree on the following targets:
  • A target HbS level of not more than 30% 2
  • A target Hct level of less than 30% 2, 3
• These targets are aimed at reducing the level of HbS while preventing hyperviscosity, which can lead to complications in patients with sickle cell disease 2, 4
• Some studies suggest that the post-RCE treatment target of 30% for the hematocrit and hemoglobin S levels is commonly used, regardless of the therapeutic indication 3
• The daily rate of rise in hemoglobin S (HbS) can be used to manage RBC depletion/exchange treatment in sickle cell disease, and a patient's average rate of rise in HbS can effectively predict the pre-procedure HbS at the following visit 5