This report is being filed to provide additional information in b.5, h.6 and h.10.Corrected information is provided in d.4.Investigation: we received blood bags (w001322802279) for evaluation.The filters were rinsed with normal saline.The normal saline flowed through the filter of w001322802279 at a slow flow rate of 4 ml/min.We disassembled the rinsed filters to observe the appearance of filter media (membranes).We noticed creases in the filter media; however, the creases were not different from those observed in conforming products.We did not observe aggregates adhered to the filter media.An airtightness test was performed on the filter in accordance with the following procedures and we confirmed that air leaks were not observed in any locations of the filter.I) the tab sheet covering the outflow side (second side) of the filter is cut out carefully and exposed the outflow side to allow observing the frame sheet (partition) directly.Ii) air is admitted to the filter from the inflow-side tube at a gauge pressure of 39.2 kpa (0.4 kgf/cm2) for approximately 10 seconds in order to check whether there is any air leakage from the frame sheet (partition).After passing normal saline through the filter, we dyed the filter media with toluidine blue for observation.We noticed that the third through sixth filter media filters were dyed dark.That is, white blood cells were accumulated in these dyed areas.In regard to the production of imuflex, sealed bags are filled with solution and the line is assembled.These bags are sterilized, stacked, and placed into the blister packs.The top film of each blister pack is heat-sealed.For the leukoreduction filter, filter membranes are punched out, laminated, and integrated into soft housing.In order to ensure leukoreduction performance and to prevent filter occlusion in and hemolysis, standards have been set to control particulate removal rates and cationization levels of each filter membrane.The standards of average cationization levels of laminated filter membranes have also been set and controlled.We reviewed the manufacturing record of the lot number in question and confirmed that no anomalies occurred in any process, and the products were manufactured as usual.In addition, we investigated dope material used for the lot number in question and found that the viscosity of pu solution of dope material conformed to the standards.Release testing, which includes measurements of solution concentration and volume and a visual inspection, is performed on the product concerned on a sample basis.We reviewed each testing and inspection record of the production number and confirmed that there were no anomalies in all release testing items.The product conformed to the standards.Regarding the retained samples of the lot numbers in question, three sets each were visually examined.There were no abnormalities in their appearances.We used one set each to measure the solution volume and used another one set each to perform a quantitative test for the composition of the solution in the same manner as the release testing.The measured results conformed to our in-house standards.Root cause: we control to maintain cationization levels above a certain level during the production of filter media in order to prevent from wbc count failure (leukocyte leakage).Where a cationization level is high, filtration rate is likely to be low.For the prevention of wbc count failure, the instructions for use of the product state: "[caution] do not squeeze or apply pressure on the filter while it is attached to the bag containing the filtered blood", and ¿clamp the blood filled tubing before blood enters the filter¿.The above-mentioned investigation results revealed that there were no abnormalities in the manufacturing record and the testing and inspection record of the lot number concerned.The returned filters also revealed no abnormalities.We noticed that the third through sixth filter media in both filters were dyed dark with toluidine blue.Therefore, occlusion may have occurred, and blood may have been filtered by the filter area which was smaller than usual, and the linear speed (flow rate per unit area) increased, and then wbc count failure (leukocyte leakage) occurred.
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