Frequent questions & answers related to the use of Sophysa products in order to help healthcare professionals deal with our valves, our ICP monitoring system, our external drainage systems and catheters.


All along the pressure range of the Sophy Mini and Polaris® models, the calibration precision is within -10/+15 mmH2O from the nominal value. The flat semi-circular spring ensures a precise and reproducible functioning pressure for each position of the rotor. It is resistant to ageing and maintains constant performance over time.
No. Adjusting a Sophy® valve with a Polaris® Adjustment Kit (and vice versa) can lead to a pressure setting error which can cause complications (overdrainage or underdrainage) with a clinical impact for the patient.

Surgical staples are made of titanium, plastic or metal (stainless steel). Metallic staples are usually amagnetic but they can have a small influence on the compass reading since they are metallic.

Valve identification

All the Sophy® and Polaris® valves are manufactured with an individual serial number engraved on the inferior face of the valve housing. Moreover, each Sophy® and Polaris® valve is packaged with a Patient Identification Card (PIC) and a set of stick-on labels mentioning the reference number, batch number and serial number. The PIC should be carried by the patient at all times, providing the information of the implanted device (reference, pressure setting,…).

The presence of one, two or three radiopaque dots, or alternatively, the absence of a dot, to the left of the inlet connector, gives the pressure range of the valve, both visually or radiographically:
– No dot: nominal maximum pressure of 140 mmH2O;
– One dot: nominal maximum pressure of 200 mmH2O;
– Two dots: nominal maximum pressure of 300 mmH2O.
– Three dots: nominal maximum pressure of 400 mmH2O;
The operating pressure range for each Sophy® or Polaris® valve is detailed on the accompanying Patient Identification Card, in accordance with the model of the implanted valve.


Sophy® or Polaris® have to be thoroughly flushed from air bubbles, either with the patient CSF or with sterile water.
The depth of implantation MUST NOT exceed 10 mm below the skin surface for Sophy® and 8 mm for Polaris®.
In addition, the Polaris valve has to be implanted on a hard bony surface to allow future pressure adjustment.
Before closing the implantation site, the arrow moulded on the upper surface of the Sophy® and Polaris® must be visible and must point in the direction of the CSF flow.

The Sophy® valve can be implanted either on the skull or in the infraclavicular fossa without any difference in the flow regulation or drainage performances. In case of chest implantation, the valve should be sutured, by using the integrated fixation holes, to the underlying fascia in order to prevent valve rotation on its axis. Chest implantation is contraindicated for the Polaris® valve since the depth of implantation is likely to exceed 8 mm below the skin surface.

The direct reading with the compass will be inverted: a pressure setting in low pressure will be read high pressure with the compass; a pressure setting in high pressure will be read low pressure.

For the adjustment of the Sophy® Mini and the Polaris® valves, the identified pole of the magnet will have to be placed to the right of the direction of the flow instead of its left.

Sophysa cannot guarantee the compatibility between the products since we do not have the full technical specifications of pacemaker. But we can communicate some informations to help you :

– We are not aware of any contraindication concerning the use of a ventriculo-peritoneal shunt on a patient with a pacemaker if the surgical technique is performed taking into account the positioning and functioning of the pacemaker and following the recommendations about catheter placement. Of course a special attention has to be paid to the pathway of the catheter passer.

– As far as the interaction of the valve and the pacemaker is concerned, please pay attention to the positioning of the valve itself, the magnets inside the valve could prevent the proper functioning of the pacemaker if positioned close to it. The magnetic fields that could come from the pacemaker, or the instruments used with it, will not interfere with the valve if they are lower than 40 mT.

– Please be aware that the valve adjustment kit (and especially the adjustment magnet) have to be handled very carefully during postoperative controls and settings. The magnetic field of this instrument is very strong (around 1.5 T when touching the magnet and far smaller some centimeters away < 0.1 T) and could impair the pacemaker functioning. For your information, we recommend a minimum distance of 50 cm between the adjustment magnet of Sophy adjustment kit and the valve during adjustment in order to limit its influence.


– polysulfone for the chamber of the valve

– synthetic ruby for the ball of the ball-in-cone mechanism

– medical grade 316L stainless steel for the valve connectors

– Samarium-Cobalt for the two micro-magnets of the valve rotor

The Sophy® and Polaris® valves are stiff, because the mechanism has to be protected against shocks, pumping operations or needle punctures. Nevertheless, its anatomic shape is especially adapted to the skull’s convexity. This non-distorting structure is insensitive to subcutaneous pressure variation, unlike silicone valves.


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. At each contact point of the spring with the ball corresponds a resistance or differential pressure. The ball-in-cone mechanism situated at the extremity of the inlet connector ensures a perfect anti-reflux function and is insensitive to temperature variations. Tests have demonstrated that Sophy® and Polaris® valves did not exhibit any reflux for outlet-inlet differential pressure of up to 200 mmHg, i.e. more than 2700 mmH2O. The spring is connected to a magnetic rotor whose position can be modified non-invasively by using an adjustment magnet. In addition, the rotor of Polaris® features a patented self-locking mechanism which prevents unintentional pressure change during everyday life and MRI magnetic fields.


The pressure setting of the Sophy® adjustable valve may be altered when exposed to strong magnetic fields. It is important to mention that this is true for other types of adjustable pressure valves on the market, except Polaris®. Outside the 0.5 mT safety line, which encircles the MRI scanner, there is no unintentional pressure change. The Polaris® adjustable pressure valve is the first adjustable pressure valve with no pressure change while exposed to a strong magnetic field such as 3 Tesla MRI. The micro-magnets included in every adjustable pressure valves are responsible for the artefacts on the MRI images. The artefacts induced by Sophy® and Polaris® valves are similar. If critical areas during the follow-up of the patient are expected to be obscured by artefacts, knowledge of the expected degree of signal void and image distortion may influence surgical decision regarding the site of implantation. There is no damage to the Sophy® and Polaris® valve mechanism even after multiple MRI exposure, meaning that the Sophy® and Polaris® valves remain adjustable. This has been demonstrated with exposure to 3 Teslas.

NO !!! Cf : study of Ortler, Neurosurgery, Vol.40, No 5, May 1997:

“… the force acting on the valves during MRI is not strong enough to dislocate or rotate a valve.”

“… the torque acting on a Sophy® Valve corresponds approximately to the torque acting on a Mc Fadden aneurysm clip.”

No heating effect at the valve fixation site has been experienced by volunteers.


The slit ventricle syndrome is due to overdrainage. The major risk is the development of a subdural haematoma.

Therefore, the valve pressure needs to be increased.

In the case described here, the valve is set to 200 mmH2O, the maximum pressure for a Sophy® Mini SM8 or Polaris® valve. It is therefore impossible to increase the pressure of this valve. The valve will have to be replaced by a specific Sophy® Mini SM8 or Polaris® valve with an operating pressure of up to 300 (SM8-300, SPV-300) or even 400 mmH2O (SM8-400, SPV-400).

The symptoms described are probably related to overdrainage.

The absence of slit ventricles on a CT scan could suggest that this is not the case, but in the presence of contradictory signs/symptoms, decisions should always be based on the clinical signs. The development of clinical signs often precedes the effects of overdrainage on ventricular volume and therefore the appearances seen on a CT scan.

In the case described:

– The valve operating pressure should be increased (moving from medium pressure (110 mmH2O) to high pressure (200 mmH2O) to reduce drainage.

– Changes in the patient’s symptoms should be monitored.

– And, if necessary, the valve pressure should be set later to an intermediary pressure.


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.

A valve works in differential pressure. It will open only if the difference of pressure between the inlet connector and the outlet connector is higher than its operating pressure.

Indeed, drainage occurs as a result of positive pressures (intraventricular pressure or ICP, weight of the height of the CSF column) and negative pressures (cerebral resistance to flow/poor compliance, valve operating pressure, catheter length and diameter, intra-abdominal pressure in case of a ventriculo-peritoneal shunt). Thus, there is little chance that the ICP will have the same value as the operating pressure of the valve.

Patient's condition

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.

A CT scan would probably show slit ventricles.

In the case described above, the valve is set at 70 mmH2O. This is a relatively low operating pressure and we would therefore recommend to increase the valve pressure. The neurosurgeon could also decide immediate drainage of the hematoma, depending on the patient’s condition.

No dedicated testings have been performed concerning hyperbaric treatment of patients implanted.

We can assume the pressure-flow caracteristics of the shunt itself during the treatment will change, reducing temporarly the flow in the shunt. Temporary flow limitation for a short period has very few clinical consequences, and the flow regulation will go back to normal right after the hyperbaric treatment.

Even though, it is recommended to pay special attention to the patient’s symptoms evolution during the treatment and in the days after.

Pressure setting

It is recommended to adjust the valve before implantation because the adjustment procedure could be somehow difficult post-operatively, due to oedema and pain. Before opening the sterile packaging, place the rotor in the position selected for implantation, by placing the adjustment magnet over the valve in the position of the packaging shell designed for this purpose, with its north pole placed to the left of the direction of the flow. Turn the magnet in order to adjust the rotor to the desired position. This pre-implantation adjustment avoids contact with the scar of the implantation site, reduces the risk of infection and ensures better patient’s comfort.

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. Pre-operative testing increases operating time and infection risks and thus, should be avoided. Neurosurgeons who use the Sophy® and Polaris® adjustable pressure valve regularly have now evidence of the reliability of the valve.

More and more neurosurgeons advocate an initial pressure setting towards the highest pressures whatever the etiology, in order to reduce the risks of overdrainage related complications:

Miyake et al., in Neurosurgery, Vol. 40, No. 5, May 1997.

«Our strategy for the initial setting of the programmable valve may have also contributed to the favorable results. We set the initial pressure at the highest level below the preoperative ICP, which may have decreased the incidence of overdrainage-related complications, even in patients with high pressure hydrocephalus.»

Lee et al., in Child’s Nerv Syst (2002), 18:533-563.

«The use of programmable shunt devices has been strongly recommended for all types of hydrocephalus and especially for NPH, but vigorous efforts should be invested in finding the optimal pressure for each patient to get the best results from shunting. Our suggestion for adjustment is to set the initial valve pressure at a level 10-30 mm H2O lower than their CSF pressure and decrease the pressure by 30 mm H2O every 3 weeks (could be shortened to 1 or 2 weeks, depending on symptoms or CT findings) until the symptoms have improved and the ventricles have normalized. We have found that this method is effective and safe in reducing the risk of complications related to over-drainage syndrome.»

By experience, the following main reasons can be listed:

– Unsuitability of the adjustment kit with the implanted valves. Be sure that the Sophy® adjustment kit (Ref RS5) is used for a Sophy® valve, and a Polaris® adjustment kit (Ref. PAK or Ref PAK-2) is used for a Polaris® valve.

– Incorrect handling of the adjustment kit. Please refer to the adjustment kit Instructions for Use or the details given in this website to be sure to use the adjustment kit correctly.

– The valve has been implanted upside down. Check if the valve has been implanted correctly on the X-Ray (see questions above).

– Valve implantation site is too deep beneath the skin surface. At the time of implantation, the depth below the skin should not exceed 10 mm for Sophy® and 8 mm for Polaris® valve. In addition, Polaris® must have been implanted on a hard bony surface. Otherwise, pressure adjustment can be impaired.

– The rotor of the valve is blocked by biological deposit. This is a known complication of the use of adjustable valves. The valve has to be explanted.

Product efficiency

Yes, yet some conditions are required. Indeed, a ventricular catheter with a reservoir or a valve with an integrated reservoir is necessary to check the patency of the shunt.


No. Our products are sterilized with ethylene oxide. They are for single use only and must not be resterilized or used if the packaging is opened or damaged, or beyond the expiry date.

If the packaging has been opened and the valve unused, it has to be returned to Sophysa for resterilization.

Surgical operation with a valve

There are no contraindications for laparoscopy on patients with Sophy® or Polaris® valves. Inflating CO2pressure ranges from 10 to 15 mmHg, is far below the anti-reflux performance of valves tested up to 200 mmHg.

However, the shorter the laparoscopic surgery, the better, since the abdominal pressure will reduce the ventriculo-peritoneal drainage during inflating.

It can also be recommended to decrease the pressure setting of the adjustable valve during surgery.


Using an external drainage system with a valve should be avoided. In case of temporary externalization of a ventriculo-atrial/peritoneal shunt with a valve, the follow-up is identical to a conventional external drainage. It will have to be performed by people having the necessary skills and under the responsibility of a physician.

It depends on the type of valve!

The Sophy® Mini valve can be used in a lumbo-peritoneal shunt. Sophysa even offers a complete kit, where the Sophy® Mini valve comes with the adequate catheters pre-attached (reference SM8-2040). The Sophy® Mini valve placed on the flank area should be fixed over a bony surface like lower ribs in order to facilitate its localization for adjustment.

To the contrary, the Polaris® valve is contraindicated for lumbo-peritoneal shunting, since the depth of implantation is likely to exceed 8 mm from the skin surface. Should it be used in a lumbo-peritoneal shunt, the Polaris® valve could be difficult to adjust afterwards.

Yes. It will have to be placed distally to the valve and the valve should be set towards the lowest pressures.

SiphonX® is the anti-siphon device from Sophysa. SiphonX® is a gravitational anti-siphon device, which will act when the patient stands up. In the vertical position, it adds 200 mmH2O to the pressure of the valve.

SiphonX® is available as a stand-alone valve accessory, or can come directly pre-connected to a valve.

Yes. In order to reduce the tension on their fragile skin, the valve has :

– a very low profile (4.6 mm thickness)

– an atraumatic shape (round edges)

– an optional antechamber (it has a very low profil, if needed)


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. From the inlet connector, on the right side of the valve there is a sequence of one, two and three dots corresponding to the 3 main pressure settings.

– One dot = low pressure setting

– Two dots = medium pressure setting

– Three dots = high pressure setting

The intermediary pressure settings can be determined by the position of the right micro-magnet in relation to the dots as shown in the pictures aside.

Each pressure setting of the Polaris® adjustable pressure valve can be easily determined both visually and on an X-ray. From the inlet connector, on the right side of the valve is a sequence of 5 dots, each dot corresponding to one of the 5 pressure settings.

When the right micro-magnet of the rotor is opposite:

– To nearest dot from the inlet connector = lowest pressure setting (N°1).

– To the furthest away dot from the inlet connector = highest pressure setting (N°5).

A valve implanted on the right side of the skull is correctly placed if the radiopaque dots indicating the pressure settings are pointing towards the patient’s nose.

A valve implanted on the right side of the skull is incorrectly placed (upside down) if the radiopaque dots indicating the pressure settings are pointing towards the patient’s neck.


Try the following steps:

1 – Disconnect and connect the USB stick again.

2 – Disconnect the USB stick, restart the monitor and connect the USB stick again.

Format (complete formatting) of the USB stick should be FAT32, with allocated unit size of 16.

3 – Change USB stick model: avoid encrypted USB sticks (risk of restarting).

In Pressio® 2:

– In default mode: every 10 ms during the last 24 h then every second.

Allows to record up to 7 patients.

– In Real-Time (RT) mode: every 10 ms during the last 15 days, 1 patient only.

In the catheter, the memory is limited to the first 15 days (non-erasable):

– Every 20 seconds for ICP.

– Every minute for ICT.

The catheter was probably disconnected before the end of the export.

Several explanations are possible:

1 – The imported RT file did not contain the complementary data on these curve parts.

2 – If an AVG import was done before the RT import, Pressio 2 does not allow the improvement.

Battery Management

Try the following steps:

1 – Disconnect the mains power for one minute then connect again.

2 – Connect to mains power, restart the Pressio 2 and wait 8 hours.

3 – Contact technical support.


Click on the help fonction “?” and follow instructions to fix the problem. If the problem persists, please contact Sophya.
Click on the help fonction “?” and follow instructions to fix the problem. If the problem persists, please contact Sophya.

1- Unplug from the mains power.

2- Dismantle the battery cover.

3- Disconnect the battery. Wait a few seconds.

4- Reconnect the battery.

5- Reassemble the battery cover. Be careful with the wire and the placement of the connector.

6- Plug in the monitor.