A pair of novel strategies may help to reduce the use of red cells among patients with sickle cell disease (SCD) undergoing red cell exchange in the case of blood supply shortage, according to a paper published in Blood Advances.

The COVID-19 pandemic has created a worldwide blood supply shortage, both because of falls in donations and the cancellation of blood drives. As hospitals begin to provide treatments that were delayed because of COVID-19, the demand for blood supplies has increased, and is approaching pre-pandemic levels.

Some patients with SCD require regular transfusions, furthermore, and specifically require Rh and K antigen-negative red cell units. Depending on the individual patient’s physical size, baseline hematocrit, hemoglobin S% (HbS%) goal, as well as individual characteristics, red cell exchanges usually require between 4 and 10 units. For this study, researchers attempted to identify strategies for reducing unit usage, to help mitigate the lower availability of blood supply during the COVID-19 pandemic.

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Overall, 50 patients with SCD who received regular red cell exchange were included. The mean patient age was 23.5 years, 32 patients were male, the mean patient weight was 48.5 kg, and 10 patients were receiving chelation therapy.

The researchers’ goal was to adopt 2 strategies to reduce the necessary red blood cell volume for successful transfusion. The first of these was to identify the target pretransfusion HbS%, and the second was to identify patients in whom it was unlikely to yield adverse outcomes if the targeted end procedure hematocrit was increased up to 5% higher than the pretransfusion level, with a maximum increase of 36%.

Overall, 33 of the 40 patients had a goal pretransfusion HbS% of less than 30. The 2 strategies led to an 18% reduction in the number of red blood cell units used among patients undergoing transfusion.

The authors noted, however, that despite this reduction, pretransfusion HbS% target goals were met. Net iron accumulation was, furthermore, maintained at a low level.

“Although COVID-19 vaccines have recently been approved, the time to reach herd immunity is estimated to be 6 to 9 months,” the authors wrote. “In the interim, measures to reduce the large red cell unit requirements for patients undergoing chronic [red cell exchange] can help ensure adequate blood for all individuals in need.”


Uter S, An HH, Linder GE, et al. Measures to reduce red cell use in patients with sickle cell disease requiring red cell exchange during a blood shortage. Blood Adv. 2021;5(12):2586-2592. doi:10.1182/bloodadvances.2021004395