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Med tech shortage in cryogenic engineering expertise

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While large scale companies, working on industrial cryogenics projects, often have in-house expertise, in the UK many smaller medical device manufacturers struggle to find trained professionals with precision engineering skill and cryogenic expertise. Because of this, many manufacturers seek specialist cryogenic consultancies to plug the gap.

In 2018 we undertook a survey among med tech manufacturers to find out how they are dealing with the shortage of skills in this very specific area of industry.

The commercial study revealed that:

  • Manufacturers prefer to outsource specialist cryogenic engineering work such as concept design, prototyping and manufacturing
  • Manufacturers expressed an increases interest in partnering with cryogenic consultancies
  • Manufacturers need a one-stop-shop resource – including problem-solving, advising, servicing, production management, safety related issues, reverse engineering, support for legacy products, new product design, innovation and product improvements
  • There are very few cryogenic consultancies in the UK and Europe which have significant experience in engineering precision cryogenic instruments and cryosurgical devices in particular

In our view, the medical device and cryogenics markets in the US are arguably more mature and the sheer volume means that there is a stronger supply chain, so more opportunity to gain the precision skills needed.

However, we have found that many cryogenicists start their careers within the industrial areas as that’s where the greatest demand is. They don’t move into the niche area of cryogenic med tech, hence the shortage of specialist skills.

If you look at the very strict regulatory nature of med tech it means that medical cryogenic engineering becomes a niche within a niche as the requirements are so specific and demanding.

Manufacturers reluctant to bring cryogenic skills in-house

The research also showed that manufacturers are wary of bringing cryogenic expertise in-house, despite the fact that their internal engineering teams have very good med tech experience but almost exclusively lacked the full cryogenic skillset.

An example of where a manufacturer might consider using existing in-house design resources could be the development of the single use cryosurgical medical device. At a glance these might appear simpler and easier to design than a reusable version, whereas in reality these stripped back products often pose even greater design dilemmas.

The devices still have to endure the same extreme operating conditions, so the challenge is to achieve performance, reliability and absolute safety in a simple and low-cost accessory, which is ultimately disposable.

Knowledge of suitable materials and manufacturing processes together with an instinctive feel for what will and won’t work is really important in achieving the best results. There is an elegance in balancing the requirements for safety and performance with simplicity and lowers possible cost and this comes from years of practical experience and experimentation in this specific field.

The cryogenics skills gap

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Companies investing in cryogenic medical device innovation seek, but don’t always find, the expertise they need. As an example, we were asked to get involved with the development of a liquid nitrogen-based cryosurgical device whose novel concept was based around greater inherent safety.

The development of a successful initial prototype, carried out by a group of specialists but disconnected sub-contractors, stalled. The main reasons for this were the lack of specific cryogenic expertise and failure to adopt an effective overall system approach.

Our design team has a uniquely diverse range of engineering design skills that cover not only the cryogenic elements but also crucial aspects of the wider system design of a cryosurgical device.

Things like fluid control, electronics, software design and all aspects of mechanical design. The ability to provide this range of expertise in-house results in greater cohesion and understanding compared with relying on separate subcontractors to do each element.

Having all relevant disciplines under one roof allowed us to achieve success while preserving the novelty and integrity of the initial technology concept.

The team were able to assess the design and make improvements very quickly. By optimising the probe tip design and also improving cryogenic transfer efficiencies, reliable performance together with greater depth of freeze was achieved.

Cryosurgical devices need to be designed so that they achieve precise, repeatable performance in order to achieve effective treatments. So many disciplines are brought together in this process. Cryoprobes are usually complex laser-welded assemblies incorporating micro-drilled holes to help control flow, in tandem with accurate pressure control systems.

The combination of invasive surgery, cryogenic temperatures and high-pressure gas can appear high risk on the face of it. This means safety is key so the system, needs to include multi-layers of protective measures.

The future of the UK’s cryogenic consultancy capability

Global companies need to see the UK as a high-quality provider of cryogenic services, for all industry sectors including med tech. It’s important that the UK becomes a major force with a strong reputation.

Nu Perspectives wants to help build this reputation alongside the British Cryogenics Council and fully support them in their efforts to enhance awareness of the inducts and the work carried out by cryogenicists across the UK.

If you're linked to the cryogenic engineering community, come and take a look at our events page. Let us know if you have any events you would like to add to our hub and help us to build a wider cryogenics-information-sharing-network. Please connect personally with Louise via Linkedin or email us directly.

Darren’s sight saving cryosurgery

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At Nu Perspectives we design, manufacture and test cryoprobes and one such probe is a device we worked with Keeler to design and develop. Recently a member of the Nu Perspectives team, Darren, whose role is to test the probes, underwent eye surgery for a detached retina and by strange coincidence the surgeon was using one of our Keeler probes to reattach the retina by using cryosurgery.

Just days before his cryosurgery, Darren had started complaining about flashing lights in his eye. He knew the flashing lights in his eye were a sign of a retinal tear as he had suffered with one in the past.

At the hospital Darren had a retinal examination which revealed that he had torn his retina again and the fluid inside his eye had leaked through the tear. The retina had been pushed away from the eye by the build-up of fluid between the eye and the retina.

The surgeon warned that although retinal tears do not usually cause vision loss, retinal detachments almost always do. It was critical that Darren underwent surgery immediately to prevent the possibility of losing his sight

Pneumatic Retinopexy, involves an injection of air, or a gas bubble, into the back of the eye. The gas bubble expands and seals the tear to prevent more fluid from leaking through it. The unwanted fluid under the retina is eventually pumped out by cells in the retina, allowing the retina to reattach. Over time, the gas bubble is replaced by a natural fluid created by the eye, until fully healed.

In his follow up appointment, Darren was told that his cryosurgery had worked brilliantly, and that the retina was now fully re-attached.

The surgeon explained that, by using both cryosurgery and laser treatment, he had been able to irritate the tissue causing it to grow and form a strong seal along the tear. After examining Darren’s eye, he commented that the cryo had done a much neater job than the laser.

The surgeon shook Darren’s hand at the end of the consultation and thanked him for doing a great job with the cryoprobes. Cryosurgery, using Keeler probes, is now common practice for detached retina and many procedures every week to help save people’s sight, using this technique.

At Nu Perspectives we are very proud of the part we play in this amazing process.

The treatment of liver cancer by cryoablation

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Some twenty years ago a surgeon called Tim Allen-Mersh, was pioneering a method of freezing cancerous tumours with liquid nitrogen. The method involved inserting a probe into a tumour, via a needle and freezing the tip to create an ice ball. The ice ball would then be used to freeze the tumour. Tim’s aim was to find a method that could not only delay symptoms resulting from the growth of the disease, and in turn sustain the patient's quality of life, but could also prolong life by controlling the disease within the liver.

In this pursuit, Tim focused his attention on finding a way to treat liver cancer by cryoablation. He was working with a liquid nitrogen system that he had used many times before, but the freeze performance was not sufficient for this particular procedure.

The system he had been using came from Spembly Medical, a company Nu Perspectives Director, Louise Cuff, was working at as a design engineer. She was asked to redesign the probe and enhance its performance. Tim wanted the probe’s diameter to decrease but the ice ball size to increase.

Louise incorporated a heat exchanger in the tip of the probe, enabling her to extract as much cold energy from the liquid nitrogen as possible. She continued to optimise the probe until she produced larger ice balls yet decreased the tip of the probe’s size from around 10mm to 5mm.

Once satisfied with the results, Louise took the probes to the Chelsea and Westminster hospital for Tim to use in surgery. Under general anaesthetic in the CAT scan suite, the patient was scanned to locate the tumour’s position. Tim then inserted a needle through the abdomen into the tumour, whilst continuing to re-scan the patient and re-position the needle until he was satisfied it was in the most effective position. He then inserted the probe percutaneously. With the needle acting as a guide he began a freeze cycle of 15 minutes. Louise's role was to advise Tim on expected ice ball size and temperature.

Louise also worked with Tim to develop a second probe to work alongside the original one. Both probes, used together, produced a bigger ice ball. This enabled Tim to treat much larger tumours, using the same method.

Working directly with the surgeon and participating in the surgical procedure, enabled Louise to match the design of the probe to his requirements. It also gave her a better understanding of how to achieve the best freezing performance possible by getting the maximum amount of cold gas and liquid in the tip of the probe.

At Nu Perspectives, we design, engineer and build prototypes, using the knowledge gained from every professional experience, to continually develop the most efficient probes and stems for our clients.

Dealing with the challenge of coupling design for cryogenics

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All engineers working in cryogenics struggle with the challenge of coupling design. It’s important not to waste liquid nitrogen while keeping the liquid cold enough to work quickly. That’s why Nu Perspectives set about creating a brand new coupling design.

The team is developing a liquid nitrogen system for cancer treatment which needs the ice ball at the end of the probe to be generated effectively. One of the issues is the coupling to connect the probe to the liquid nitrogen supply. The system is also a low flow system.

Here are the results we have achieved so far in this project:

The problem as soon as liquid nitrogen comes into direct contact with the coupling it starts to boil, turns into gas and stops the cold liquid reaching the probe tip.

We needed to achieve nucleate boiling at the tip quickly, to create an effective ice ball. This is particularly important when designing cryogenic surgical instruments. Any increase in the time to get to optimal freezing reduces the effectiveness of the surgical probe.

With this problem in mind and the fact that it was a low flow system, we decided to design and test the coupling and to measure the effect on the probe.

Adding the extra thermal mass of the coupling increased the time it took to get 100% liquid to the tip as the liquid boiled in the coupling. Adding the coupling also increased the time to achieve nucleate boiling in the tip of the probe, meaning it wasn’t working efficiently.

At Nu Perspectives we are able to create and test working prototypes on the premises, making it much easier and cheaper for us to carry out very precise tests and changes on instruments, until they are working effectively.

Firstly we looked to limit the length of the flow path of liquid nitrogen in direct contact with the coupling body material. This reduced the amount of liquid boil off in the coupling which had a positive effect. However, it meant the whole coupling body froze, so our next step was to take out as much of the coupling material as possible.

This had a positive impact on the results but not enough so we insulated the part of the coupling that was still in direct thermal contact with the liquid nitrogen, and this improved the performance further.

This is an ongoing project and while we have made significant progress we are still working to further reduce the time to nucleate boiling at the tip. Our approach has demonstrated that very small changes can make a big difference to the performance of an overall cryogenic system.

We are very lucky to have the in-house prototyping facility which really does make an enormous difference to this kind of precision engineering work. While this project is still ongoing we know that couplings are used in lots of cryogenics applications and that our findings could help others in the field.

If you are interested in collaborating or ideas sharing on any cryogenics or liquid nitrogen projects, then please get in touch.