3D printed Cardioplegia clamp solution

Bennett Engineering Design Solutions has developed a bespoke 3D printed Cardioplegia clamp for King’s College Hospital Foundation Trust, one of the UK’s largest teaching hospitals.

The head of clinical perfusion science for the Trust, Michael Whitehorne, approached Bennett Engineering Design Solutions late last year to help develop a bespoke solution to support the use of Cardioplegia Sets in its operating theatres. The Trust had been pleased with the quality of a pressure gauge holder developed previously by the design team and wanted a clamp based on similar principles.

“The clamps that were available at the time for holding the Cardioplegia Set’s heat exchangers which cool down the patient’s blood during cardiac surgery, were no longer meeting the Trust’s requirements,” explained John Bennett, director, Bennett Engineering Design Solutions. “The clamps simply didn’t secure the heat exchangers well enough, they could also be slow and difficult to use.”

The Trust required a complete design rethink; it needed a solution that would attach easily to standard masts and instrument stands as the heat exchanger must be quickly changed in an emergency. The unit needed to be easy to clean and suitable for sterilisation. It must also be possible to adjust the orientation of the heat exchanger through 360° so blood can run without interruption and the set’s tubes not be strained.

“The challenge with the design was to create the right geometry to satisfy the Trust’s requirements,” Bennett continued. “The initial prototype needed to be improved to make the changeover quicker. Adjusting the geometry of the catch took two iterations, we also needed to minimise the number of parts required, to ensure ease of use while being aesthetically pleasing too. The clamp for example, features an over centre clip finger for the attachment so the removal of the heat exchanger is simple and intuitive to use.

“We chose to develop our design using 3D printing as we believed it offered greater flexibility on the design geometry, enabling us to create more organic shapes. This was then followed by the material Alumide, to deliver a tough, highly professional ‘look and feel’ to the end product.”

Alumide is a versatile material made up of nylon and grey aluminium powder and provides both lightness and strength. It is cost effective to print and can be sealed for cleaning and sterilisation - ideal for certain types of medical equipment.

The completed design used standard components along with 3D printed parts to achieve a simple and cost effective solution. By adopting 3D printing, complicated geometry and shapes could be included at no extra cost, allowing the design team far greater design freedom to deliver improved aesthetics.

No manufacturing tools were required, which helped to ease the design update and change of parts during the product development process, which took eight weeks to complete and has been in use by the Trust since June 2016. It now benefits from a bespoke design solution, rather than the generic clamps produced in high volume by heat exchanger manufacturers.