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Improving safety of at-home medical devices

Healthcare organisations are seeking solutions to treat patients in home care settings to reduce the burden on traditional healthcare facilities. While this approach improves patient comfort and convenience, it can be difficult to manage compared to a controlled clinical setting where care is administered by trained medical professionals. When a home medical device manufacturer approached industrial heating technology manufacturer Watlow, for a thermal solution for its home hemodialysis device, Watlow delivered an innovative solution that not only met requirements for size and safety, but also improved the overall system. 

According to the National Kidney Federation, around 30,000 people are on hemodialysis in the UK. Hemodialysis is the procedure where blood is cleaned using a dialysis machine with a filter acting as an artificial kidney.

In-home care allows for more frequent treatment, improving patient outcomes while reducing the overall cost of therapy. In the medical device market, this trend has been a double-edged sword. On one hand, it has increased the demand for certain medical devices. On the other, it has led to greater scrutiny of devices and increasingly stringent safety standards. Measures used to increase safety precautions are often at odds with the need to make home care devices smaller and more portable than those used in a clinical setting.

While at home medical devices are improving comfort and convenience for patients, a number of regulations arise regarding safety. Specifically, IEC 60601-1-11 outlines safety requirements for medical devices intended for use in home care settings. Manufacturers must identify the specific product safety risks associated with using their equipment in a non-clinical environment. To achieve certification, manufacturers must mitigate those risks through appropriate product design, in addition to clear user instructions and training.

Safety, size and portability

An important consideration for any automated medical device is electrical safety. In the design of these machines, some features are considered MOPs (Means of Protection). Medical devices need two or more MOPs to reduce the risk of electrocution. Traditionally, MOPs have been added to devices with a trained third-party operator in mind (usually in an in-patient setting), in addition to MOPPs (Means of Patient Protection).

A clinical setting allows MOPPs that are not usually present in a home setting, since the patient is now also the operator. Manufacturers must include those MOPPs in the medical device itself, which creates some additional design challenges. In a home care setting, higher levels of patient safety are required than in a clinical setting.

This is largely down to the absence of device training and the risks surrounding voltage and outlets. In a hospital, the electrical outlets are guaranteed to have appropriate voltage, be effectively grounded and tested and certified as safe. But these guarantees cannot be made for a patient’s home. As a result, MOPPs must provide much more protection, as the safety requirements for home care devices will be that much more stringent, and the clinical assumptions about operator health and training cannot be assured. In this case, responsibility for ensuring safe operation shifts to the device manufacturer. 

Thermal system considerations

Home hemodialysis machines include a final challenge — fluids must be kept at body temperature to prevent thermal shock. Higher temperatures are also needed to disinfect the machine itself. Unsurprisingly, the heating requirements of these medical devices greatly influence both the size and the electrical requirements of the machine. Heating fluid on demand requires a fair amount of power, increasing the possibility of current leakage, and the risk to patients.

Mitigating those risks is possible with more traditional technology, but that technology adds to both the bulk and cost of medical devices. This is where innovation in thermal solutions, including heaters, sensors, temperature controllers, power controllers and supporting software working together as an integrated system, can make a difference. Watlow’s engineers used knowledge of the full system standards and system level requirements to help the customer create an optimised system architecture for its home hemodialysis device. This featured a FLUENT in-line heater with a ceramic substrate tube and polymer fittings to create an entirely non-metal surface.

The FLUENT heater addresses efficiency and electrical safety concerns with a size and weight footprint that is smaller than legacy solutions. In addition, using thermal spray, the heater makes use of its entire surface to produce heat, which optimises heat transfer and temperature uniformity.

 The goal of Watlow’s customer was to design a home hemodialysis device that met all safety guidelines while being portable and convenient for patient use. Using a systems approach helped Watlow to navigate the engineering tradeoffs between size and safety without compromise, to produce a safe device with a small footprint.

Watlow has extensive experience understanding how to meet the required trade-offs and develop a design suitable for many applications. Visit the website to find out more watlow.com