Measures to reduce red cell use in patients with sickle cell disease requiring red cell exchange during a blood shortage

Key Points Availability of pretransfusion HbS% values before red cell exchange facilitates calculation of precise donor unit numbers required. Raising the red cell exchange end hematocrit can reduce red cell units required as a short-term measure to conserve blood in a shortage.
The COVID-19 pandemic has created major disruptions in health care delivery, including a severe blood shortage. The inventory of Rh and K antigen–negative red cell units recommended for patients with hemoglobinopathies became alarmingly low and continues to be strained. Because patients with sickle cell disease requiring chronic red cell exchange (RCE) incur a large demand for red cell units, we hypothesized that implementation of 2 measures could reduce blood use. First, obtaining the pretransfusion hemoglobin S (HbS) results by procedure start time would facilitate calculation of exact red cell volume needed to achieve the desired post-RCE HbS. Second, as a short-term conservation method, we identified patients for whom increasing the targeted end procedure hematocrit up to 5 percentage points higher than the pretransfusion level (no higher than 36%) was not medically contraindicated. The goal was to enhance suppression of endogenous erythropoiesis and thereby reduce the red cell unit number needed to maintain the same target HbS%. These 2 measures resulted in an 18% reduction of red cell units transfused to 50 patients undergoing chronic RCE during the first 6 months of the COVID-19 pandemic. Despite reduction of blood use, pretransfusion HbS% target goals were maintained and net iron accumulation was low. Both strategies can help alleviate a shortage of Rh and K antigen–negative red cells, and, more generally, transfusing red cell units based on precise red cell volume required can optimize patient care and judicious use of blood resources.
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