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How the right thermal solution can meet medical safety standards

Healthcare organisations are increasingly moving patients to home care settings to reduce the pressure on traditional healthcare facilities, especially since the COVID-19 pandemic. However, this has been a double-edged sword for medical device manufacturers. On one hand, it has meant a boom in the market for certain home medical devices, but it has also led to greater scrutiny of devices and increasingly stringent safety standards. Andy Selvy explains how and why medical device manufacturing needs a new approach.

IEC 60601-1-11 standard for medical electrical equipment requires manufacturers of home medical devices to identify product safety risks associated with using their equipment in an uncontrolled environment by untrained users. 

Meeting safety standards is sometimes possible with traditional technology, but that technology adds to both the bulk and the cost of medical devices. Device manufacturers understandably want to make devices that are smaller, cheaper and easier to use — goals that are often at odds with safety compliance measures. This is where innovation in thermal solutions, including heaters, sensors, temperature controllers, power controllers and their supporting software can make a difference.

Thermal system safety

Many medical devices require heaters to warm gas or liquids, and these require a fair amount of power that increases the possibility of leakage current and hence the risk of electrocution. This is a great example of where stricter standards for home care medical devices exist and how evolving heating technology can better meet those standards.

Unlike medical devices in a clinical setting, home medical devices cannot be designed with the assumption that there is a trained operator on site that can use tested outlets and equipment according to a set procedure. As a result, safety precautions must be built into the device design itself.

One way to improve patient safety is to incorporate an isolation transformer to step down the voltage going into the device, similar to the ‘brick’ used to step down voltage for a smartphone charger. But isolation transformers are notorious for being big, bulky and expensive, which works against the goal of miniaturisation for home medical devices.

Safety versus miniaturisation

So, what is the solution to ensuring safety without the need for bulky and expensive technology? It starts by designing devices within a systems approach.

For instance, it’s not sufficient to create a heater that runs at 95 microamps leakage so that it can be incorporated into a device that must be rated to run under 100. Although this type of heater would meet the given specification, it would take up most of the available leakage budget.  Adequate heater design of the entire thermal system must take into consideration these difficult system level requirements.

Andy Selvy, chief system designer, Watlow

Designing heaters with a systems approach

New generation of thermal solutions are being used to ensure safety and economy of space especially in home haemodialysis machines and respiratory devices.

With haemodialysis machines, it’s necessary to keep blood at body temperature to prevent thermal shock. Higher temperatures are also needed to disinfect the machine itself. Watlow’s FLUENT in-line heater can achieve the desired temperatures quickly and efficiently, while meeting space and safety constraints. This is attributed to the small, lightweight design, which acts as an integrated solution that replaces multiple components in a system 

Furthermore, Watlow’s heating technology also improves respiratory solutions, where a high flow of oxygen must be maintained, like in COPD devices. The compressed gases tend to be cold and dry, creating irritation and often, patient rejection. Watlow’s ULTRAMIC heater can be used to warm and humidify the gas quickly without requiring a large transformer or bulky heating elements.

Today, home medical devices must meet higher safety standards, while maintaining a small user-friendly, lightweight design. But to achieve this, components must be designed with a systems approach in mind. This involves using thermal components that optimise devices by making them smaller, lighter and with greater thermal performance that makes use for the patient easier and more comfortable.

Andy Selvy is chief system designer at industrial heater manufacturer Watlow.

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