Alternative method to determine the hematocrit of red blood cell units: a potential use in the apheresis unit

In automated erythrocytapheresis procedures, achieving the desired-end hematocrit (Hct) requires that the COBE Spectra (CaridianBCT) machine be programmed with the mean Hct of the replacement red blood cell (RBC) units. To determine unit Hct, data derived from quality control (QC) Hct data were utilized. However, if a unit volume is outside the quality control (QC) volume parameters, the unit is accessed to measure its Hct. In this study, 21 percent of all RBC units need to be accessed to determine the Hct, which affects 47.5 percent of patient's erythrocytapheresis procedures. Spiking the unit compromises its integrity and hastens the expiration time of the unit. Nurses must wait until the patient arrives to check units outside QC parameters, thereby delaying the start time of procedures. Even if sampled units are kept refrigerated, they cannot be returned to the blood bank inventory once spiked. The goal of this study was to determine if accurate Hct levels from RBC units could be obtained from a unique segment. To determine the centrifuged Hct, samples were prepared from the RBC units and compared to that of the unique segment. The Hct of the unique segment exceeded that of the RBC unit by a small (1.2% in AS-1 units, 0.92% in AS-3 units), but statistically significant amount. The Hct from unique RBC segments closely approximates that of the original RBC unit. Unique segments can be made that will maintain the integrity and shelf life of RBC units.