Translation of flexSTIM: a biomimetic implanted pattern generator for effective long-term pressure injury prevention through automated weightshifting and enhanced tissue health.

About This Grant

Pressure injury (PrI) prevention remains a major challenge over the long term for Veterans with impaired mobility, in particular those with spinal cord injury (SCI). PrI limit activities of daily living, often leading to prolonged bedrest, hospitalization and even death. Clinical practice guidelines recommend weight-shifting every 20 minutes for persons with SCI, which is impractical when busy with activities of daily living. We have previously shown that long term use of dynamic gluteal intermittent stimulation (iGSTIM) using percutaneous electrodes and an external stimulator effectively provides an extra means of weight shifting, improves local blood flow, increases muscle size and reduces the incidence of tissue breakdown, specifically pressure injuries. User feedback was that long-term use of iGSTIM meant they no longer worried about recurrent skin problems requiring significant periods of bedrest. Furthermore, daily use of the system was easy and fit well in to their activities of daily living. However, continued usage is necessary to sustain improvements in tissue health and the need to keep percutaneous lead exit sites covered and regularly cleaned became arduous over time. Users requested a fully implanted iGSTIM for regular weight shifting and PrI prevention. Our team has been contacted many times over the years by individuals asking for a system that could be entirely implanted. Other prevention methods these individuals tried have failed and they are desperate for a new alternative. We have therefore developed the flexSTIM biomimetic implantable pattern generator (IPG). Prior funding synergized recent advances in flexible hybrid electronics, additive manufacturing and packaging with our prior clinical findings to provide initial development and testing of the flexSTIM IPG laying the foundation for translation and clinical implementation in persons with SCI. Combined with industry-standard intramuscular (IM) electrodes, the VA-patented flexSTIM Class III IPG is a novel technology that proactively addresses the issues of decreased muscle quality and the long-term need for regular weight-shifting for persons with limited mobility, in particular Veterans with SCI. This small flexible 2-4 channel system meets the end user need for straightforward automated weight-shifting and can be initiated daily at the touch of a button. The flexSTIM IPG is designed to be inserted into a subcutaneous pocket through a 1” incision, with the whole iGSTIM system implemented as an outpatient procedure. The complete iGSTIM system comprises the implanted battery-free flexSTIM IPG and IM electrodes, together with an external radio frequency coil and telemetry controller. The goals of this milestone driven project are to complete all pre-clinical testing required to obtain a full Investigational Device Exemption (IDE). Benchtop testing and GLP preclinical biocompatibility testing to ISO 10993 standards will be initiated during the first year of the project. Long-term in-vivo testing of the iGSTIM system's function, reliability and safety will also take place based on FDA guidance. Successful completion of preclinical testing will provide the foundation for our full IDE submission to enable an early feasibility study in 10 Veterans with SCI. The conditionally approved IRB protocol proposed under the full IDE will be reviewed by the FDA. All project activities will be milestone driven using robust and clear quantitative decision criteria and includes pivot points if needed. Project milestones include further meetings with the FDA during as needed as the project proceeds. All activities proposed for this project will be within the intended scope of providing support for technical and regulatory assistance not typically supported by other VA award mechanisms. The fully implanted iGSTIM system has enormous potential to enhance health and quality of life for Veterans with SCI.