Rotational Moulding Saves Lives

Midas Pattern Company has used its expertise in rotational moulding to help bring an innovative medical training device to market.

BRISTOL, UK – The Chest Drain and Needle Decompression Trainer, which features a host of complex features, was devised by Bristol-based Limbs & Things, and is a potential life-saver.

Limbs & Things was established in 1990 by medical illustrator Margot Cooper. Now the company’s President, she has identified a growing need for a form of training away from live patients, cadavers, and animals.

“A chest drain is a common medical procedure and one that is often life-saving,” says Piers Bentley, design engineer at Limbs & Things. “Events such as a car accident or military incident can easily lead to blood or other fluids entering the chest cavity where it can cause serious problems. Performing chest trauma procedures has potentially fatal risks if the medical practitioner, such as a junior doctor, has not had sufficient training.”

The company wanted to develop a product, complete with interchangeable modules, which would allow for a variety of chest drain insertion techniques to be performed including ultrasound-guided techniques.

Rotational moulding offers relatively low tooling costs and the ability to produce complex hollow products in economical short runs. In comparison with blow moulding, rotational moulding permits the production of much more complex, asymmetrical shapes, while wall thickness distribution is also more uniform.

“We’ve had some experience with rotational moulding,” explained Mr. Bentley. “However, we reviewed a couple of new mould shops and opted for Newark-based Rototek. However, due to the tight deadline involved we were also keen to keep the tooling in the UK and Rototek suggested Midas due their track record of quality and on-time deliveries.”

After completing the initial CAD work, Limbs & Things and Rototek met with Midas Pattern Company at the company’s Bedford headquarters to discuss the project. “It was a good meeting as Midas helped to devise ways to tackle some fairly complex details,” says Mr. Bentley. “For instance, the model includes water-tight over-moulded features – we needed a method to secure our internal ultrasound anatomy, such as diaphragmatic structures and collapsed lung, into the model without the use of external fixings. With the experience and advice offered by Midas we came up with an innovative way of producing an internally moulded undercut, which works brilliantly.”

The chest trauma training model is a waist-up representation of the adult male thorax with arms raised, comprising four main parts – the left and right chest cavity, the shoulders, and the abdomen. Each section required Midas to produce six- or seven-part rotational mould tools. The result is a training simulator offering capability way beyond existing chest drain models. Features include bony and soft tissue landmarks such as manubriosternal joint, clavicles, ribs, pectoralis major, and latissimus dorsi, as well as bilateral chest drain and needle decompression pads.Furthermore, the reservoirs can be filled with fluid or mock blood to represent pleural effusion, while decompression air reservoirs provide realistic release of air upon needle insertion.

“In the whole process I think we only required one design change – and Midas made the adjustment and returned tooling within a week,” says Mr. Bentley.

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Each section of the training device required Midas to product six- or seven-part rotational mould tools.