Visual inspection: no significant deformations or damage of the valve were detected during the visual inspection.Permeability test: a permeability test has shown that the valve is permeable.Adjustment test this is a fixed pressure valve.An adjustment test is not applicable.Braking force and brake function test: this is a fixed pressure valve.A braking force and brake function test is not applicable.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 both the horizontal as well as the vertical positions.The results show that the valve operates within the accepted tolerance in both positions.Results: first we performed a visual inspection of the shuntassistant®.No significant deformations or damage of the valve were detected during the visual inspection.Next we tested the permeability of the valve.The valve was shown to be permeable.Then we carried out a computer controlled simulated flow test.The measured opening pressure was within the accepted tolerance in both positions.Finally, we have dismantled the valve.Inside the valve we have found a significant build-up of substances (likely protein).Based on our investigation, we are unable to substantiate the claim of under-drainage.At the time of our investigation, the valve was operating within the specified tolerances.However, it is possible that the significant deposits observed inside the valve could have caused the malfunction in the past.As described in our literature, the problem encountered is one of the known, inevitable risks of hc-therapy by shunt implants.We can exclude a defect at the time of release.The valve met all specifications of the final inspection when released from christoph miethke (b)(4).
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