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What is the mechanism of the Sophysa Adjustable Pressure Valves? |
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The principle of the Sophy® and Polaris® adjustable pressure valves is based on the pressure variation exerted on a ball by a flat semi-circular spring at various points of its curvature ... |
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Out of which materials are the Sophysa Adjustable Pressure Valves made? |
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Main component of the valve is polysulfone, the material of the chamber of the valve. |
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What is the precision of the calibration of the Sophy® Mini and Polaris® Adjustable Pressure Valves? |
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All along the pressure range of the Sophy Mini and Polaris models, the precision of calibration is within -10/+15 mmH2O from the nominal value ... |
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Why are the Sophy® and Polaris® valves stiff? |
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The Sophy® and Polaris® valves are stiff, because the mechanism has to be protected ... |
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Can we use an anti-siphon device with the Sophy® and Polaris® valves? |
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Yes. It will have to be placed distally to the valve and the valve should be set towards the lowest pressures ... |
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What about adjustment of the Sophy® or Polaris® valve before implantation? |
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It is recommended to adjust the valve before implantation because the adjustment procedure could be somehow difficult post-operatively, due to oedema and pain ... |
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Do you recommend a pressure test before implanting a Sophy® or Polaris® valve? |
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No. As each valve has been individually calibrated and controlled with specific high precision equipment, it is unnecessary to perform any additional testing prior to implantation ... |
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Is there any precaution to be taken during the implantation procedure of the Sophy® or Polaris® valve? |
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Sophy® or Polaris® have to be thoroughly flushed from air bubbles, either with the patient CSF or with sterile water ... |
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Is there any recommended pressure setting for Sophy® or Polaris® at the time of implantation? |
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More and more neurosurgeons advocate an initial pressure setting toward the highest pressures whatever the etiology, in order to reduce the risks of over-drainage related complications ... |
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Is it possible to implant a Sophysa adjustable valve in a lumbo-peritoneal shunt? |
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Well, it depends on the type of valve! The Sophy® Mini valve can be used in a lumbo-peritoneal shunt... |
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Is there any difference in flow regulation between skull and chest implantation of a Sophy® valve? |
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The Sophy® valve can be implanted either on the skull or in the infra-clavicle fossa without any difference in the flow regulation or drainage performances ... |
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How should one read the pressure setting of the Sophy® valve on X-Ray film? |
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The main pressure settings of the Sophy® adjustable pressure valve can be easily determined both visually and radiographically by means of a standard identification code ... |
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How should one read the pressure setting of the Polaris® valve on an X-Ray film? |
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Each pressure setting of the Polaris® adjustable pressure valve can be easily determined both visually and on X-Ray ... |
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What does a radio-opaque dot to the left of the inlet connector to the Sophy® or Polaris® valve indicate? |
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The presence of one, two or three radio-opaque dots, or alternatively, the absence of a dot, to the left of the inlet connector ... |
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From an X-ray, what is the method to be sure that an implanted Sophy® or Polaris® valve is correctly in place (engraved arrow on the skin side), or upside down (engraved arrow on the skull side), regardless of the side from which the X-ray film is read? |
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A valve implanted on the right side of the skull is correctly placed if the radio-opaque dots ... |
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What about adjustment if the Sophy® or Polaris® valve has been implanted upside down (arrow seated on skull side instead of skin side)? |
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The direct reading with the compass will be inverted: a pressure setting in LP will be read HP with the compass ... |
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What could be the main reasons for difficulty or failure of the pressure adjustment on an implanted Sophy® or Polaris® valve by a physician? |
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By experience, the following main reasons can be listed ... |
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Is it possible to test the patency of the shunt once the Sophy® or Polaris® valve has been implanted? |
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Yes, some conditions are required ... |
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Can the patient feel some noise from the Sophy® or Polaris® valve implanted on the skull? |
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Yes. This is quite frequent and whatever the disturbance it may cause, it also means that the shunt is functioning well ... |
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What is the incidence of MRI on the pressure settings of the Sophy® and Polaris® valves? |
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The pressure setting of the Sophy® adjustable valve may be altered when exposed to strong magnetic fields ... |
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Is it possible that the Sophy® and Polaris® valves be dislocated from their implantation site under MRI? |
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NO !!! Cf : study of Ortler, Neurosurgery, Vol.40, No 5, May 1997 ... |
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Is there any heating effect from the Sophy® or Polaris® valve under MRI? |
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No heating effect at the valve fixation site ... |
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What is the relationship between operating pressure of the valve and intracranial pressure? |
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The operating pressure does not correspond to intracranial pressure, but is only the resistance of the valve to CSF flow. Catheters also add resistance to the CSF flow ... |
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What to recommend for a patient with a Sophy® SM8 or Polaris® SPV valve set at 110 mm H2O who complains of headache when he is standing, which resolves when he lies down, and in whom a CT scan shows normal size ventricles? |
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The symptoms described are probably related to over-drainage ... |
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What to recommend for a patient with a Sophy® SM8 or Polaris® valve set to 70 mm H2O in whom an early sub-dural haematoma has been diagnosed? |
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Development of a subdural haematoma in a patient with hydrocephalus fitted with a shunt probably indicates a well-known side effect, which is a consequence of overdrainage ... |
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What is the slit ventricle syndrome due to, in a patient fitted with a shunt with a valve? How would this be solved in a case in which the patient was carrying a Sophy® SM8 or Polaris® SPV set to 200 mm H2O? |
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The slit ventricle syndrome is due to over-drainage. The major risk is the development of a subdural haematoma ... |
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What precautions does a patient fitted with a Sophy® Mini Adjustable Valve have to take in his everyday life? |
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Magnetic fields generated by airport security doors, microwave oven, mobile phone, high tension wire, TV, etc..., can potentially alter the pressure setting of the Sophy® valve ... |
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Is it possible to place the Sophy® or Polaris® valve between a ventricular catheter and an external drainage system? |
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Using an external drainage system with a valve should be avoided. In case of temporary externalization of a ventriculo-atrial / peritoneal shunt ... |
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Are there any contra-indications in performing laparoscopic surgery on patients with Sophy® or Polaris® valve? |
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There are no contra-indications for laparoscopy on patients with Sophy® or Polaris® valves ... |
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How is it possible to trace the Sophy® and Polaris® valves? |
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All the Sophy® and Polaris® valves are manufactured with an individual serial number etched on the inferior face of the valve housing ... |
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Can a Sophysa valve be re-sterilised? |
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No. Our products are sterilised with ethylene oxide ... |
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