Investigation is completed: opening pressure upon intake at the time of intake, the progav showed a pressure setting of 1 cmh2o.Visual inspection: the following observations were made during the visual inspection: deformation of the housing.Measurement of surface of the housing to verify whether the deformation had an effect on the plane-parallelism of the housing surface, this was measured using a dial gauge.The measurement of the plane parallelism confirmed the observations of the optical inspection.The measured value of -0,023 mm lies not within the given tolerance (0 ± 0.02mm).Permeability test: the test showed that the progav is permeable.Computer controlled test in order to investigate the suspicion of over-drainage, the progav was tested on a miethke computer controlled testing apparatus.The valve was tested by simulating a cerebrospinal fluid flow at rates from 60 ml/hr down to 5 ml/hr with the valve in horizontal position (in accordance with iso 7197).Distilled water was used as the test-liquid.The resulting opening pressure was measured.The computer controlled test has shown the opening pressure of the progav, at a reference flow rate of 20 ml/hr in a horizontal position, to be 0,90 cmh2o.This is within the specified tolerance of 1 cmh2o ± 3 cmh2o.An applied pressure of 1 cmh2o, with the device in the horizontal position is expected to have a resultant opening pressure of 1 cmh2o ± 3 cmh2o.Adjustability test: the progav was adjustable to all pressure setting.Braking force and brake function test: the braking force of the progav was not within the specified tolerance and the brake function operated as expected.This malfunction could be due to the deformation of the housing surface.Internal inspection of product: in order to verify whether the investigated valve was compromised by the known risks of hydrocephalus therapy, e.G.By a build-up of natural substances (protein, blood, or tissue particles) in the cerebrospinal fluid, we have dismantled the valve.After dismantling of the valve, clearly deposits were found in the progav.Results based on our investigation, we are not able to substantiate the claim of "over-drainage"" however, we assume that the significant deposits found within the valve may have temporarily caused the functional impairment.Deposits caused by natural substances in the cerebrospinal fluid, such as protein, blood or tissue particles, are among the known and unavoidable risks and side effects of 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 (b)(4).From our point of view, no further regualatory actions are required.
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