There are inherent risks when it comes to wireless technology in medical electronic devices – security, performance, coexistence, EMI and privacy.

Q: What are the requirements for effectively deploying and managing wireless medical devices?

By R. Srinivasan, Principal Software Engineer, Cambridge Consultants

Nowhere are the demands on wireless technology more complex and more critical than in the medical device industry. From diagnostics to in-hospital care and monitoring, from the operating theater to patient medical records, wireless technology is changing the healthcare industry and raising design and deployment challenges along the way.

Hospital environments are especially vexing for wireless devices coping with EMI created by anything from the reflective signal characteristics of a building to the multitude of electronic devices crowding a patient's room or treatment area. EMI can degrade device performance and reduce system reliability. Better standards and regulations address some of these issues as well as advanced antenna design. Yet "designing around" EMI issues with techniques such as frequency agility at the physical layer or forward error correction in the data layer can optimize system performance.

Interoperability is always a factor in wireless design, but medical facilities use a complex array of application-specific devices that harness frequencies or standards from IEEE 802.11, Bluetooth, WMTS and even MICS for implantable devices. The emergence of IEEE 11073, providing data layer compatibility, has the potential to improve the situation, but bridges or gateways may still be required to achieve full interoperability. Security and protecting patient privacy and healthcare records in a wireless environment impacts consumer confidence and acceptance, and it is central to helping a healthcare institution meet the complex array of compliance issues such as HIPAA.

Some of these security solutions are found at the silicon level with stringent encryption standards and high-level application and enterprise security support. Yet the healthcare market is just beginning to look at privacy and security from a product lifecycle vantage, coping with how to protect a device and data from initial deployment through its use and final disposal.

Deploying new wireless medical technologies create both opportunities and challenges. By "designing in" solutions from wireless interoperability to better patient interfaces, we will continue to see the advancement of wireless solutions into the healthcare market.

By David A Case NCE, NCT, Technical Leader Regulatory, Cisco Systems

There are inherent risks when it comes to wireless technology in medical electronic devices — security, performance, coexistence, EMI and privacy.

There are a number of issues which present some level of risk when deploying wireless in medical devices or in the medical environment; however, there are also a lot of benefits. The privacy and security issues can be addressed up-front before installation once the requirements are identified. The other three issues may need to be addressed after installation as well. In fact, the EMC related issues will most likely be monitored by the technical staff on an ongoing basis once the system is installed.

What are the requirements for effectively deploying and managing wireless medical devices? Basically the issue comes down to understanding the risks and, more importantly, planning on how to mitigate them. The FDA offers a guidance document on the use of wireless in medical devices and in the medical facility is a good place to start. The document provides an overview of the risks, explains them a bit as well as offers guidance on addressing some of the issues. This information can be supplemented with additional information in the IEEE 11073 standards addressing wireless point-of-care systems.

From the EMI side, it is always recommended to do an on-site assessment in acordance with ANSI C 3.18 before the wireless system is installed. This will help reduce the chances of interference. Remember, the key is to formulate a plan to help you effectively identify and then mitigate the risks factors which, in turn, will help provide the benefits of wireless in that deployment.

By Jonathan Bearfield, Texas Instruments

The requirements for effectively deploying and managing wireless medical devices are highly dependent on the size of the network the device interacts with, the amount of data that needs to be transmitted, the overall size of the device and the transmit range required. Of course, the criticality of the equipment’s purpose is a key factor as eliminating the impact of interferers and supporting a high level of selectivity is much more important in an implanted defibrillator than a fall detector. However, these performance variables are captured in the elements listed above.

Although wireless interfaces like Wi-Fi or Wireless LAN, Bluetooth and Wibree lend themselves easily to larger network implementations especially with Wibree’s ability to leverage many of the components already used for Bluetooth technology their range and the number of interferers in the device’s operating environment can make their use problematic in some applications. As such, many implantable and critical care devices look towards proprietary solutions, giving them better control and understanding of their EMI, sensitivity, selectivity and range requirements. At this time the Continua Alliance appears to be moving forward with Bluetooth as their choice for a wireless solution platform.

Additionally, ISM, MICs, MedRadio and Zigbee solutions are being looked at for use in medical devices. For example, using Zigbee for home patient monitoring allows the device to tap into a potentially pre-existing home security system for communication back to the health care provider. But, as explained earlier, this would be leveraging a well defined and confined operating environment around the device to manage risk.

By defining and limiting the system size and the amount of data to be transmitted, the system’s radio and antenna definition can be tightened, reducing the risks from EMI, impact of interferers as well overall size of the device because the power and thermal management requirements are also reduced.

Unfortunately, although narrowly focusing the system in which a wireless medical device needs to interact helps decrease the performance risks for the device, it also stalls the proliferation of interoperable wireless medical devices as this implementation prohibits the formation of a common communications infrastructure for all devices.