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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, deformations of the housing or other abnormalities.The following observations were made during the visual inspection: -scratches -bloody tissue residues permeability test: the permeability test was performed at a hydrostatic pressure difference of the pressure setting of the m.Blue upon receipt plus 30 cmh2o in the horizontal direction of flow.The test showed that the m.Blue with the pedi.Prechambers 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 differential unit of the valve, at a reference flow rate of 20 ml/h in the horizontal position, to be 12,89 cmh2o.This is within the specified tolerance of 10 cmh2o ± 3 cmh2o.Additionally, the gravitational unit of the valve was tested according to standard procedure in the vertical position.The results indicated that at a reference flow of 20 ml/h, the gravitational unit of the m.Blue® had a pressure of 14,45 cmh2o.This is within the specified tolerance of 19 cmh2o +6/ -12 cmh2o.Adjustability test: in this step, it was investigated whether the adjustable m.Blue can be successfully set to each specified pressure setting.It was checked whether the valve is fully adjustable within the full range of specified pressure settings ( in increments of 4 cmh2o).The m.Blue was found to be adjustable to all pressure settings.Braking force and brake function test: the braking force and brake function test investigates whether the brake function of the adjustable valves is present and how much force must be exerted on the housing to release the rotor to adjust the valves using the integrated magnet of a specific measurement apparatus of braking force.The braking force of the gravitational unit of the m.Blue was within the specified tolerance and the brake function operated as expected.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, no deposits were found inside.For more detailed visibility, the proteins/deposits in m.Blue® were coloured by using a colouring solution.Colouring solution consisting of coomassi brilliant blue r mixed with 0.6% ethanol and distilled water.Results: based on our investigation results, we cannot detect any malfunction or deposits.The cause of the aforementioned functional impairment is not known to us at the time of the examination.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.Return of product: we will return the investigated product to the sending clinic for our own relief.
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