BioMed Central Page 1 of 1 (page number not for citation purposes) Cerebrospinal Fluid Research Open Access Oral presentation Controversies about the adjustment of gravitational valves in respect to a new device Christoph Miethke* 1 , Christian Sprung 2 and Michael Kiefer 3 Address: 1 GmbH & Co.KG, Ulanenweg 2, 14469 Potsdam, Germany, 2 Neurosurgical Department University of Berlin, Charité, Germany and 3 Neurosurgical Department University of Homburg, Germany Email: Christoph Miethke* - [email protected] * Corresponding author Background The essential drawback of available adjustable devices for the treatment of hydrocephalus is the fact that the adjustment is valid for both positions of the patient. If the opening pressure is increased to decrease the risk of over drainage in the upright position of the patient the same adjustment leads to a very high opening pressure while the patient is lying and consequently to an under drainage in the horizontal position. On the other hand the lower- ing of the opening pressure automatically increases the risk of subdural effusion as soon as the patient is in upright position. Materials and methods A new device has been developed to introduce the possi- bility of a valve adjustment, which is effective only in the upright position of the patient. Hereby it is possible to ensure a very low opening pressure of the device in the horizontal position and an adjustment of the high-pressure chamber for the upright position depending on the needs of the individual patient. The adjustment of the valve works similar to the proGAV, which introduces a mechanical brake to avoid unintended readjustments of the device. To establish a posture depending function of the valve the gravity of a titanium disc acting on a sapphire ball defines the opening pressure of the upright position. The weight of this titanium disc is counterbalanced by an adjustable spring-force. At the lowest adjustment the whole weight of the titanium disc acts against the sapphire ball, at the highest adjustment the whole weight is counterbalanced and the gravity of the titanium disc has no impact on the opening pressure of the valve. Results The new device fulfils the physical requirements for a shunt to differentiate between the horizontal and vertical position of the patient. The adjustment of the valve pressure independent of the posture of the patient is impor- tant especially for patients with untypical intra- abdominal pressures, for female patients during preg- nancy or patients with unclear clinical outcome. Conclusion The new device offers new possibilities especially for patients with NPH and children. from 50th Annual Meeting of the Society for Research into Hydrocephalus and Spina Bifida Cambridge, UK. 30 August – 2 September 2006 Published: 21 December 2006 Cerebrospinal Fluid Research 2006, 3(Suppl 1):S2 doi:10.1186/1743-8454-3-S1-S2 <supplement> <title> <p>50th Annual Meeting of the Society for Research into Hydrocephalus and Spina Bifida</p> </title> <note>Meeting abstracts – A single PDF containing all abstracts in this supplement is available <a href="http://www.biomedcentral.com/content/files/pdf/1743-8454-3-S1-full.pdf ">here</a>.</note> </supplement> © 2006 Miethke et al; licensee BioMed Central Ltd.

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Page 1: Controversies about the adjustment of gravitational valves in respect to a new device

BioMed Central

Page 1 of 1(page number not for citation purposes)

Cerebrospinal Fluid Research

Open AccessOral presentationControversies about the adjustment of gravitational valves in respect to a new deviceChristoph Miethke*1, Christian Sprung2 and Michael Kiefer3

Address: 1GmbH & Co.KG, Ulanenweg 2, 14469 Potsdam, Germany, 2Neurosurgical Department University of Berlin, Charité, Germany and 3Neurosurgical Department University of Homburg, Germany

Email: Christoph Miethke* - [email protected]

* Corresponding author

BackgroundThe essential drawback of available adjustable devices forthe treatment of hydrocephalus is the fact that the adjust-ment is valid for both positions of the patient. If the open-ing pressure is increased to decrease the risk of overdrainage in the upright position of the patient the sameadjustment leads to a very high opening pressure whilethe patient is lying and consequently to an under drainagein the horizontal position. On the other hand the lower-ing of the opening pressure automatically increases therisk of subdural effusion as soon as the patient is inupright position.

Materials and methodsA new device has been developed to introduce the possi-bility of a valve adjustment, which is effective only in theupright position of the patient. Hereby it is possible toensure a very low opening pressure of the device in thehorizontal position and an adjustment of the high-pres-sure chamber for the upright position depending on theneeds of the individual patient. The adjustment of thevalve works similar to the proGAV, which introduces amechanical brake to avoid unintended readjustments ofthe device. To establish a posture depending function ofthe valve the gravity of a titanium disc acting on a sapphireball defines the opening pressure of the upright position.The weight of this titanium disc is counterbalanced by anadjustable spring-force. At the lowest adjustment thewhole weight of the titanium disc acts against the sapphireball, at the highest adjustment the whole weight is coun-

terbalanced and the gravity of the titanium disc has noimpact on the opening pressure of the valve.

ResultsThe new device fulfils the physical requirements for ashunt to differentiate between the horizontal and verticalposition of the patient. The adjustment of the valve pres-sure independent of the posture of the patient is impor-tant especially for patients with untypical intra-abdominal pressures, for female patients during preg-nancy or patients with unclear clinical outcome.

ConclusionThe new device offers new possibilities especially forpatients with NPH and children.

from 50th Annual Meeting of the Society for Research into Hydrocephalus and Spina BifidaCambridge, UK. 30 August – 2 September 2006

Published: 21 December 2006

Cerebrospinal Fluid Research 2006, 3(Suppl 1):S2 doi:10.1186/1743-8454-3-S1-S2

<supplement> <title> <p>50th Annual Meeting of the Society for Research into Hydrocephalus and Spina Bifida</p> </title> <note>Meeting abstracts – A single PDF containing all abstracts in this supplement is available <a href="http://www.biomedcentral.com/content/files/pdf/1743-8454-3-S1-full.pdf ">here</a>.</note> </supplement>

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