Executive Summary:

HD designed, developed, and engineered a novel device and drainage system which connected to an indwelling catheter to draw excess pleural fluid from the chest cavity or, peritoneal fluid from the abdominal cavity and drain into a compact, low cost and low-profile drainage bag. The main aims of the project were to reduce the physical size, cost and complexity of drainage, whilst affording improved pressure control to prevent discomfort for the patient.

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HD worked with both primary and secondary users such as HCP’s to identify user needs before applying engineering expertise to afford these requirements. HD’s design afforded users and clinicians more control over the drainage process including drainage speed and volume control thus reducing patient discomfort from excessive negative pressure in a discrete and compact manner. The new device also calculated the amount of fluid discharged and was future proofed for data transfer and the IoMT.

It is worth saying that we have been very impressed by the work that has been produced!

The main aims of the project were to reduce the physical size, cost and complexity of drainage, whilst affording improved pressure control to prevent discomfort for the patient.

Following a research and immersion phase, we determined this could be achieved by using a novel system to provide the controlled negative pressure required for comfortable drainage. This would provide a significant improvement over the pre-set vacuum pressure provided by existing drainage bottles. Using the new device would also allow for a simpler, lower cost and smaller drainage container to be used, for example, a urostomy-drainage bag.

An important element of the project was usability engineering therefore it was vital to understand the end user and the effects of treatment on their condition. For this device, the end user could be a patient alone or, with assistance of a secondary user such as a healthcare professional. The typical drainage procedure and use period of the device would be 10-30 minutes, and typically used at least daily over a period of days, weeks or months.

HD’s approach started by mapping the individual user steps when using an existing IPC suction device. This included role playing the use of the existing devices by utilising equipment such as restrictive gloves and vision impairment glasses to simulate, understand and empathise with a user’s experience. As a result of a function mapping exercise, opportunities for reducing the number of user steps were identified as well as opportunities for improving the usability of various components. HD then began exploring the industrial design of the device and developing early-stage concepts, consistently evaluating designs in relation to the brief and, previous findings through observation.

To improve awareness, some of the HD team attended training workshops with clinicians who typically perform the procedure of inserting a plural catheter. This provided important insights surrounding existing devices and allowed a user journey map to be gathered. Building a relationship with these clinicians allowed HD to gather valuable feedback and input throughout the design and development process.

Risk analysis as well as regulatory and safety reviews were performed regularly throughout the project to ensure designs met international regulatory requirements and engineering standards. From this point, there was a strong focus on engineering and performance development of the new device.

In addition to designing a novel device which calculated volume of discharge, there were a number of other requirements to achieve. One of which being the ability to measure and define air vs liquid. A number of testing and simulation tools were used throughout the process to ensure solutions were engineered to meet these performance requirements. FEA software was used as a tool to establish the volume of fluid displaced in one cycle. A simple, non-linear, large displacement FEA model was created. To achieve this, FEA results were exported and built as a SolidWorks part, allowing HD to take measurements and therefore calculate the volume of fluid displaced in a set time.

The process described was repeated for 3 different configurations and the results extrapolated using a best fit power curve to establish the optimum device features to deliver the required flow. As a result of further research and testing, the maximum negative pressure within the Pleural cavity was calculated allowing HD to define the maximum torque and power requirements of the device.

Based on calculations on the average period of use and amount of liquid drained over a 30-day course, we focused on enhancing the device’s power performance whilst using standard AA batteries. This would ensure the device would perform the required number of drainage procedures during its intended lifecycle without needing to replace the batteries.

HD developed a proof of principle lab prototype based upon the chosen concept. The prototype was intended to test the fundamental operating principle, to move fluid at the desired flow rates, at the required pressure. It also allowed for research to create a platform to test ideas such as air sensing for further development and to generate a future product development road map for the client.

The prototype was built using 3D printed parts allowing for quick iterations of different design variations. In addition, different tube configurations were created for comparative testing.

These concepts were then thoroughly compared and reviewed in relation to a number of factors including regulatory issues and potential for IP protection with a host of further concepts created for our client to consider. Enhancements to device usability and performance were also made as a result of clinician’s feedback so the motor was mechanically isolated from the enclosures by a rubber moulding to reduce noise and any potential vibrations felt by the user.

The device utilised a small motor with a series of innovatively engineered clips and rollers to create a an action to draw the fluid into a non-invasive collection bag. The design and technology allowed the device to calculate the exact amount of fluid discharged and the patient was able to control the device by adjusting flow rate to minimise any discomfort from negative pressure. The new design also meant a regular drainage bag could be used thus reducing cost and significantly reducing device size too. In addition, the device was future proofed for data transfer to HCP’s monitoring systems and the IoMT.

If you would like to learn more about this project or discuss how we can help with your product or medical device development, please get in touch.

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