Investigation: visual inspection: during the visual inspection a deformation of the outer housing of the progav valve could be determined.The measurement of the plane parallelism could confirm that with a value of -0.065 mm - outside tolerance (0 ± 0.02 mm).Permeability test: a permeability test has shown that all components are permeable.Computer control test: to investigate the claim of under-drainage, the opening pressure is measured using a miethke computer control test bench which simulates a cerebrospinal fluid flow.The valves are tested in both the horizontal as well as the vertical positions.The results show that the both valves are not operating within the acceptable tolerance in either position.An accelerated outflow of both valves could be determined.Adjustment test: the progav was tested and is not adjustable.Braking force and brake function test: the brake functionality test has shown that the brake function is operational.However, the braking force cannot be measured due to the non-adjustability of the valve.Internal inspection: after dismantling of the valves, deposits were found in both valves.Results: based on our investigation results, we can determine an accelerated outflow and adjustment difficulties.The detected deformation and the visible deposits on the inside of the valves can influence the function.Organic deposits 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 shunt system met all specifications of t no further regulatory actions are required from our point of view.
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