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3D Printed Tesla VP Shunt Valve

Sterile 3D printing of ventriculoperitoneal shunt valve and other components in developing countries

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Untreated hydrocephalus is a major cause of mortality and poor neurological outcome in the developing world with estimated incidence of 1/1000 live births. Unfortunately many hospitals in the developing countries are not equipped to handle this condition. This is astounding given that hydrocephalus is a very treatable. CSF diversion procedures such as a ventriculoperitoneal shunt (VP shunt) have been performed in routinely in resource limited settings with good outcomes. However one roadblock to delivering this care has been the lack of availability of shunt components forcing surgeons to use ad-hoc improvised shunts. We aim to overcome this by manufacturing some of these sterile components we have designed with 3D printing onsite within a hospital for patients.

Problem Statement:

Lack of properly functioning ventriculoperitoneal shunt components have forced surgeons in some developing countries to use ad-hoc improvised devices which have a high complication rate. This paper (https://www.ncbi.nlm.nih.gov/pubmed/9299832/) from Malawi describes how surgeons simply diverted CSF from ventricular cavity into the peritoneum without an intervening valve with a 20% complication rate which included subdural hematomas and shunt associated craniosynostosis.

This other paper (https://www.ncbi.nlm.nih.gov/pubmed/26167009?dopt=Abstract) from Nigeria describes using a nasogastric tube for creating an external ventricular drain or ventriculostomy and report 28.6% MORTALITY (death) rate.

Additive manufacturing can create these shunt valve components with precision, sterility [new literature has demonstrated the inherent sterility of 3D printed parts (https://peerj.com/preprints/542/) if certain protocols are followed], and reproducibility in a resource limited setting but requires rethinking paradigm. They can be powered independent of national electric grid on solar panels.

Aims:

1) Improve outcomes of patients suffering from hydrocephalus in developing countries

2) Build partner nation's capacity for treating hydrocephalus by manufacturing parts with FDM 3D printing on site at hospitals decreasing reliance on imported medical devices.

3) Empower partner nations to design and create its own medical devices which are often expensive and drain precious foreign currency reserves.

Existing Solutions:

Commercially available ventriculoperitoneal shunts consist of a fixed pressure valve, proximal, and distal catheters. If we are to successfully manufacture a 3D printed valve we need to rethink the paradigm of the valve.

The valve housing consists of silicone. It includes an integrated reservoir (the circular part) that allows surgeon to sample CSF in the event of malfunction or suspected infection.

The valve also contains a one-way check valve (metallic object resembling miniature telegraph). In standard designs this can consist of numerous moving precisely machined parts- something that makes manufacturing a shunt in resource limited setting challenging.


reed shunt valve.mix

Meshmixer file of fluidic rectifier by J. Reed

mix - 173.33 kB - 04/02/2017 at 05:05

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  • Establishing Testing Rig

    Sohum Desai MD04/05/2017 at 00:23 0 comments

    VP shunt valves prior to implantation are tested with a manometer setup as follows:

    What you see here is a three way stopcock, manometer (vertical plastic tube marked in increments of centimeters), an adaptor for the outflow nozzle of the 3 way stopcock, and the shunt valve. The switch on the three way stopcock is turned so that the shunt valve is closed. A syringe filled with saline is then attached to the inflow used to fill the manometer. The switch of the three way stopcock is then turned so that the valve is closed.

    At this point the column of saline in the manometer will drain out of the distal end of the valve.

  • Tesla Conduit

    Sohum Desai MD04/02/2017 at 20:47 0 comments

    Rather than re-creating a miniature check valve consisting of mircomilimeter sized components, I googled 'valve with no moving parts' and to my surprise found the following:

    Source: https://en.wikipedia.org/wiki/Tesla_valve

    Nikola Tesla described this device in 1920 allowing fluid to move preferentially in one direction. Although the fluidics have fallen by the way side, I see a useful application of this design in our shunt valve that can be easily manufactured on a 3D printer.

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