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Visual inspection: in the first step of our investigation, we performed a visual inspection of the product.We have checked for possible damage, deformation of the housing, deposits or other abnormalities.The following observations were made during the visual inspection: no visible defects at the gav 2.0.Tissue residues in the control reservoir, but no visible obvious damages.Permeability test: the permeability test was performed at a hydrostatic pressure difference of the pressure setting of the gav 2.0 shunt system upon receipt plus 30 cmh2o in the horizontal direction of flow.The test showed that the gav 2.0 shunt system is permeable.Computer control test: to check the flow rate of the valve, the valve was tested on a miethke computer controlled testing apparatus and passed the standard test.The flow of the test liquid was reduced step by step from 60 ml/h to 5 ml/h (in accordance with iso 7197).Distilled water was used as the test-liquid.The resulting pressure was measured.The computer controlled test showed the opening pressure of the gav 2.0, at a reference flow rate of 20 ml/h in the horizontal position, to be 5,66 cmh2o.This is within the specified tolerance of 5 cmh2o [-1 / +3] cmh2o.Additionally, the gav 2.0 was tested according to standard procedure in the vertical position.The results indicated that at a reference flow of 20 ml/h, the gav 2.0 had a pressure of 28,75 cmh2o.This is within the specified tolerance of 30 cmh2o [-2 / +4] cmh2o.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, the valve is finally opened with a special tool.After dismantling of the valve, deposits were found in the gav 2.0.For more detailed visibility, the proteins/deposits in gav 2.0 were coloured by using a colouring solution.[colouring solution consisting of coomassi brilliant blue r mixed with 0.6% ethanol and distilled water].Results: we would like to note in advance that the returned product was not submerged in liquid (leaked) at the time of receipt.The testing of valves sent in in a dry condition is only of a limited value.The product performance can be affected by dry residues of cerebrospinal fluid or blood.Despite this we have tested the device to the best of our abilities.Based on our investigation results, we can determine deposits.The deposits had no affect to the technical properties at the time of the investigation.The cause of the aforementioned functional impairment is not known to us at the time of the examination.Proteins 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 the final inspection when released from christoph miethke gmbh & co.Kg.Further actions: from our point of view, no further regulatory actions are required.
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