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Background During storage, the potassium level of red blood cell (RBC) components increases, especially after irradiation. Neonates are prone to hyperkalemia, for example, non-oliguric hyperkalemia, so using potassium adsorption filters during transfusion may be helpful. To overcome dilution of RBC components caused by saline priming of existing potassium adsorption filters, a downsized potassium adsorption filter for neonates (PAF-n, Kawasumi Laboratories Inc., Tokyo, Japan) was developed. Study design and methods To assess the performance of PAF-n, its adsorption efficiency and RBC recovery rate were evaluated by testing pre-filtration and serial post-filtration (0-30 mL, 30-60 mL, 60-90 mL, and 90-120 mL) samples from 8 RBC components. Results The average potassium adsorption rate of the PAF-n was 90.5% ± 0.78%, and never less than 89.0% in any of 8 RBC components. RBC recovery rates were 99.3% ± 1.12%. Conclusion The PAF-n showed an effective potassium ability with negligible RBC dilution.

Aims: Clinically significant antibodies may become undetectable and still provoke transfusion reactions. Hemolysis has been reported among transfusion recipients with anti-Kidd that was undetectable by gel column but detectable by other methods. Methods: We compared two automated technologies - microplate (MP) and gel column (GC) methods - with manual methods in ABO/RhD typing, irregular antibody screening, identification, titration, and detection threshold of mixed-field agglutination. Results: Automated systems agreed generally with tube results in 98% or more of ABO forward and RhD groupings, but showed weaker reactions in ABO reverse testing against A1 (K=0.88 with MP and K=0.77 with GC) and B cells (K=0.66 with MP and K=0.68 with GC) and failed to detect some anti-A (2 of 273 samples with MP) and anti-B (2 of 273 with MP and 1 of 272 with GC). MP missed 2 (anti-E and –Fyb) of 8 antibodies and GC missed 5 (2 anti-E and 1 each of -Fyb, -Jka and –Lea) of 10 antibodies, which manual PEG-IAT detected. Among 11 known alloantibodies, MP detected 7 antibodies at higher dilution than tube PEG-IAT, whereas GC showed lower scores in 7 samples than tube PEG-IAT and missed 2 clinically significant antibodies (anti-C and anti-Fyb). Conclusion: Automated systems, comparable to manual tube technique for forward grouping of ABO and RhD, are less sensitive in ABO reverse testing. As GC more often failed to detect clinically significant antibodies of low-titer, users should be especially mindful of possible post-transfusion hemolysis.