Overview

Sterling Medical Devices performed design services for a Class III breathing pacemaker with Major Level of Concern software, intended for use by patients who have lost neurological control of respiration. This life-sustaining device is comprised of two main components: an internal passive receiver and an external controller. The device was intended to replace an outdated predicate device. Sterling designed the hardware and software for the external controller and performed system design verification. The receiver was not designed by Sterling. Sterling had experience with the client prior to the adoption of this project. For over a decade, Sterling has assisted the client on several smaller design projects. After Sterling completed these projects, the client chose to return with a larger undertaking.

Challenge

Design
The predicate device contained a fully analog design, which had become obsolete and difficult to obtain parts for. It also contained an outdated user interface. Therefore, the client requested an updated, digital solution with a new, user-friendly interface. Additionally, the device’s RF communication circuitry contained issues that the client decided not to address due to the budgetary concerns. This presented a design challenge for Sterling to work around.

Verification
The device requirements provided to Sterling by the client were not testable and the device would, therefore, not meet FDA regulations. In order to ensure regulatory approval, Sterling also worked with the client to refine the Design History File.

Resources
Throughout the project life-cycle resource availability fluctuated due to an inconsistent project timeline. Despite resource constraints Sterling remained agile in its approach to this constraint and reorganized the team several times to best suit the ever-changing needs of the client as well as the task(s) at hand. The project was able to continue unabated despite this resource turnover because of Sterling’s exceptional documentation and standard design processes.

Process

Design
Sterling conducted a complete redesign of the external controller, updating the outdated analog solution to a modern digital solution. This redesign mirrored the predicate device’s inputs, outputs, and overall functionality in order to serve as a one-to-one replacement. Additionally, Sterling refined the user interface to include a keypad for inputs and a custom LCD screen for outputs. As is common for the design of Class III devices, Sterling designed a fully independent, redundant hardware solution in the external controller in case of software failure. Multiple microprocessors were incorporated, each dedicated to a unique task. When faced with the constraints placed on the design by the RF communication circuitry, Sterling provided the client with several recommended courses of action, allowing the client to make decisions based on which path best suited them.

Verification
Sterling refined the Design History File for this device in order to better meet the FDA’s usability and safety requirements. This was done largely by rewriting existing requirements in order to improve testability. Sterling also helped the client define and test corner cases for uncommon processes that were not considered in the existing DHF in order to ensure patient safety.

Result

Sterling was able to overcome design challenges and create an updated, more robust external controller for the client that has received FDA and EU approval and is now used in over 20 countries. Sterling was also able to utilize its extensive experience with Class III devices and its diverse design background to offer several design solutions, catering to the development process to best suit the client. Sterling has also performed many redesigns of outdated devices for other clients, and was able to bring this prior experience to the table for this project.