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TWI Assists in 3D Printed Respiratory Support System

Tue, 19 May, 2020

TWI Technology Centre Wales is pleased to have been able to assist the University of Wales Trinity St David (UWTSD) in the development of a 3D printed respiratory support system to aid patients with breathing difficulties due to the Coronavirus.

Engineers at UWTSD began the rapid development of a highly efficient 3D printed jet Venturi-based respiratory support system following calls from Welsh Government and industry to develop rapidly manufactured CPAP solutions to aid SARS-CoV-2 patients with breathing difficulties. The project team, which was assembled a little over a month ago, is being led by Mr Graham Howe and Mr Luca Pagano from MADECymru along with Professor Peter Charlton, Mr Richard Morgan and Mr John Hughes from the university’s School of Engineering. The team assembled staff with experience in the fields of engineering, as well as drawing upon the expertise of John Hughes - one of UWTSD’s final-year undergraduate engineering students - to carry out vital computational modelling.

The solution for the system was created by investigating Post-Graduate project work from the School of Engineering at UWTSD that outlined the potential use of the Venturi effect for gas therapy. Healthcare professionals and industry groups confirmed that the primary challenge for SARS-CoV-2 gas therapy was the high level of oxygen use. This high demand is due to the number of active patients and consequent low oxygen availability as a result of infrastructure overload and losses caused by inefficient, existing appliances. The means that oxygen consumption is the main parameter for the optimisation and modelling process.

The Venturi effect, which is mostly found in so-called Venturi jet ejectors (used in hydraulic/gas systems), can provide entrainment of a secondary fluid or gas as a consequence of an optimised nozzle geometry from which a motive fluid flows. Essentially, when combined with the right physical geometries, this allows patient delivery of a controlled pressurised range of mixtures of air / oxygen by connecting the oxygen line available in hospitals; with no electric supply required.

The first experimental validation was undertaken at Singleton Hospital in Swansea on 6 May.  The tests gave the team the opportunity to compare the performance of physical prototypes to the analytical and computational models previously used to design and optimise the system geometry. This validation test indicated that the system is able to deliver 40% and 65% FiO2 (Fraction of Inspired Oxygen) respectively at 2 and 6 litres per minute of oxygen volume flow.  The tests prove that such a configuration could out-perform most of the available CPAP (continuous positive air pressure) devices. The Venturi systems show a potential to deliver 24%FiO2 with less than 1 litre per minute of oxygen volume flow.

The team’s aim is to develop a solution that is freely accessible to health authorities from every country in need. Therefore, from a manufacturing perspective, the team have already developed a number of different bespoke solutions.  A number of different assembly options are possible, which can comprise off-the-shelf medical circuit connectors or a fully 3D printed system (this is the prototype currently undergoing tests). All of these options interface with the patient using a readily available, low cost, adjustable anaesthesia mask held in place by a 3D printed brace. The 3D printed fully functional prototype, as it stands, could potentially be a downloadable plug and play device, making it available anywhere in the world. The system is also able to interface with standard PEEP Valves and Viral Filters to protect both patients and workers. All at a cost of £5/6 worth of materials.

A pre-production prototype was created with assistance from TWI Technology Centre Wales in CT-Radiography NDT&E tolerance deviation analysis, while CBM provided additive manufacturing assistance.  

Graham Howe, Principal Research Fellow (Advanced Manufacturing) at UWTSD said, “It’s been a challenging, yet rewarding experience, working with a multi-disciplinary team of Engineers from the University, each bringing their own expertise to drive the development of this device. We have also had superb support from our long-standing industrial partners, without whom, we couldn’t have completed this work. This project has shown what can be achieved when organisations join forces for the national good and we hope that this device will help support the fantastic work the NHS frontline staff are doing to treat Covid-19 patients.”

TWI is proud to have been able to assist UWTSD with this important project and the full system is now undergoing extensive failure mode and effect analysis, as well as further testing.

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