Investigation: visual inspection: in the first step of our investigations, we carried out a visual inspection of the valve.Then the prosa valve housing is measured to rule out the presence of any deformation.Permeability test: to proof the penetrability of the valve we have carried out penetrability test.This test is carried out at a hydrostatic pressure of approximately 20-30 cmh2o in the direction of flow.Adjustment test: our adjustment tests are carried out with the standard prosa checkmate and measurement tool.The valve is adjusted from 0 to 40 cmh2o and down again in increments of 4 cmh2o.Braking force and brake function test: to measure the braking force, we tested the prosa valve with a braking force apparatus.Here it is measured how much force must be exerted on the housing to release the rotor to adjust the valve by the integrated magnet of the braking force apparatus.Results: first, we performed a visual inspection of the prosa.A deformation of the outer casing of the prosa valve was observed through the visual inspection.The deformation was subsequently confirmed through a measurement of the parallelity of the valve housing.The housing deformation measured at -0.07 mm, outside the tolerance of 0 ± 0.02mm.Next, we tested the permeability of the valve.The test result show that the prosa is permeable.To ensure that the valve is adjustable we tried to adjust the valve from 0 cmh2o to 20 cmh2o and down again in increments of 4 cmh2o.The valve was not fully adjustable to specifications.Next, we tested the braking force and brake functionality.The brake function is operational; however, the braking force cannot be measured due to the non-adjustability of the valve.The cause of the deformation of the prosa valve could not be determined through our investigation.Significant outside pressure, for example by too much force from the prosa adjustment tool or by a fall or impact to the head of the patient, can compromise the integrity of the valve.In order to verify whether the 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.Inside the valve we have found build-up of substances (likely protein), which may have caused the suspected malfunction in the past.Based on our investigation, we confirm the presence of a blockage from the adjustment, likely due to the deposits observed inside the valve.As described in scientific 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 shunt system met all specifications of the final inspection when released from christoph miethke gmbh & co.Kg.
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