The customer would like the run data file investigated to determine a possible cause for the elevated white blood cell (wbc) content in the platelet product.There was not a transfusion recipient or patient involved at the time of the residual wbc testing, therefore no patient information is reasonably known at the time of the event.This product is not available within the us, but this report is being filed due to an alleged failure that could occur on a similarly marketed device platform cleared for use by the fda.The platelet collection set is not available for return because it was discarded by the customer.
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Investigation: the set concerned was not available and we therefore conducted the following investigations based on the information provided.In regard to the filter used for the product in question, the filter media is formed (membrane making process) followed by the cutting process, warming process, staking and punching process, and housing assembling process.Review of the manufacturing record of the lot number in question was performed.There was no equipment trouble causing the issue concerned and it was confirmed that the equipment had operated properly, and no anomalies had been observed.The manufacturing records regarding particulate removal rates of filter membranes that were likely to be related to filtration performance were reviewed.It was confirmed that all filter membranes conformed to all standards.Release testing, including a visual inspection and other items, is performed on the product concerned on a sample basis.We reviewed each testing and inspection record of the lot number in question and confirmed that there were no anomalies in all testing items.The product conformed to the standards.Three sets of retained samples of the lot number concerned were visually inspected.There were no abnormalities, such as tubing occlusion and blockage, in their appearances.Root cause: from the above-mentioned investigation results, we did not observe any abnormalities in the manufacturing process of the lot number concerned.As mentioned in the investigation results above, the filter membranes of the product concerned consist of a rough-pore pre-membrane (the first filter membrane) and minute-pore main membranes (the second through eighth filter membranes).According to the data at the time of designing of the product in question, there is a possibility of white blood cell contamination when the particulate removal rates are low.However, as mentioned above, the particulate removal rates of the lot number concerned were within the standards and did not show a low tendency.Therefore, we were not able to identify the cause of the issue.Leukoreduction failure is commonly caused by the following factors: 1) blood characteristics of donors there is a possibility of leukoreduction failure due to blood characteristics of donors.2) pressure loaded on filter membranes for some reason, where a physical stress on filter membranes is greater than what is expected, trapped white blood cells are pushed out of the filter membranes and may result in leukoreduction failure.For the prevention of leukoreduction failure, the instructions for use (ifu) 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".Based on the investigation results of similar issues which we received in the past, a general cause of leukocyte reduction failure can be cited that pressure was applied to the collection bag or the filter during the filtration process of the collected blood.
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