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Investigation: visual inspection: during the investigation, no significant deformations or damage of the valves was determined.Permeability test: a permeability test has shown that the valve is permeable.Computer controlled test: to investigate the claim of under-drainage, the opening pressure is measured using a miethke computer controlled testing apparatus which simulates a cerebrospinal fluid flow.The valve is tested in vertical position.The results show that the valve is operating not within the accepted tolerance in the vertical position.A slower outflow could be determined.Internal inspection : after dismantling of the valve, deposits were found.To make the proteins / deposits in the valve more visible, they were colored using a staining solution.Results: based on our investigation results, we can determine a slower outflow in the valve.The determined deposits can be named as the cause for the slower outflow.Proteins in the cerebrospinal fluid can influence the function temporarily and are known side effects in hydrocephalus therapy.We can exclude a defect at the time of release.The valve met all specifications of the final inspection when released from christoph miethke gmbh & co.Kg.No further regulatory actions are required from our point of view.
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