Investigation: visual inspection no significant deformations or damage of the valve was detected during the visual inspection.The progav valve housing was subsequently measured and indicated a slightly presence of a deformation.The housing deformation measured at -0.026 mm, outside the tolerance of 0 ± 0.02 mm.Permeability test a permeability test has shown that the progav valve is permeable.Adjustment test the progav valve was tested and is adjustable to all specified pressures.Braking force and brake function test the brake functionality test has shown that the brake function operates as expected.However, the breaking force required was not within the specified tolerances.Computer controlled test to investigate the claim of over-drainage, the opening pressure is measured using a miethke computer controlled testing apparatus, which simulates a cerebrospinal fluid flow.At the first measurement, the valve does not operate within the allowable tolerance.At the second measurement, the valve operates with the acceptable tolerance.This can be caused by rinsing during the test procedure.Results first, we performed a visual inspection of the progav valve.No significant deformations or damage of the valve was detected during the visual inspection.Next, we tested the permeability, adjustability and opening pressure of the valve, as well as the brake functionality and brake force.The opening pressure and the braking force of the progav valve was out of tolerance, but all other specifications were met.The opening pressure of the progav was significantly lower than expected, indicating a tendency towards over-drainage.Finally, we have dismantled the valve.Inside the valve, we have found build-up of substances (likely protein).Based on our investigation, we confirm that the progav valve was operating in an over-drainage state at the time of our investigation.This is likely due to the deposits observed inside the valves.As described in scientific literature, the problem encountered is one of the known, inevitable risks of hc-therapy by shunt implants.The cause of the deformation of the progav valve and the resultant of the lower braking force could not be determined through our investigation.Significant outside pressure, for example by too much force from the progav adjustment tool or by a fall or impact to the head of the patient, can compromise the integrity of the valve.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.
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