“The ability to use nearly 20% fewer red cell units is a tremendous savings in this current national shortage, helping ensure all patients who need blood will have blood available to them,†said Stella Chou, MD, of Children’s Hospital of Philadelphia. “While raising the hematocrit can only be implemented as a short-term measure, having the pre-exchange hemoglobin quantification prior to the procedure can result in significant unit savings as well, by allowing precise calculation of red cells needed.â€
Dr. Chou and colleagues enrolled 50 patients with SCD who were on a chronic RCE program. The mean age of the patients in the study was 23.5 years (range = 9-44).
Pretransfusion HbS goals for patients enrolled in the study were as follows:
- <30% (n=33)
- <35%-45% (n=8)
- <50% (n=9)
Most commonly, transfusion therapy was indicated for primary stroke prevention (n=16) and secondary stroke prevention (n=23). The patients in the study cohort required RCE every three to five weeks with a corresponding RBC unit requirement ranging between two and 10 units.
The first studied strategy was the acquisition of pretransfusion HbS results by the start time of the procedure to calculate the exact RBC volume required to achieve a desired HbS after RCE. Secondly, the researchers modestly increased the targeted end hematocrit “to enhance suppression of endogenous erythropoiesis,†which was performed in 43% of procedures and for 11 patients.
Ultimately, this led to an increase of the fraction of cells remaining (FCR) needed to maintain the target HbS, which led to reductions in the units transfused. The average per-patient FCR rose from 43.4% before the pandemic to 52.4% during the pandemic in patients with an HbS goal of <30% (p<0.001). Additionally, the mean FCR per patient increased from 48.7 to 54.7% for the <35 to 45% group (p=0.022) and from 54.8 to 60.6% for the <50% group (p=0.013).
While 1,594 units were transfused during a six-month study period, a total of 351 units (18.0%) were saved. The average number of RBC units transfused for each procedure was reduced from 6.1 to 5.0 units (p<0.001). There was a significant correlation between the percentage of units saved for each patient during the pandemic and the patient’s mean FCR increase from their procedures before and during the COVID-19 era (p<0.001).
The percentage increase in FCR for the procedures performed during the COVID-19 pandemic was greater in patients with increased hematocrit compared with patients with unchanged hematocrit (p=0.035), a finding which the researchers suggest is consistent with fewer transfused units per RCE.
While there was an overall reduction in blood use, the HbS target goals prior to transfusion were maintained, while net iron accumulation remained low.
This study is limited by its small sample size. Dr. Chou added that further research should also examine whether other institutions could have similar blood unit savings if the same measures were implemented.
Study authors report no relevant conflicts of interest.