Originally Published MEM Spring 2007
FROM THE EDITOR
Wireless medical devices are certainly streamlining work flow. At the very least, they eliminate cumbersome cords in often tight spaces in hospitals and doctors' offices. But, are they safe? As more of them are put into an environment, can they coexist? FDA certainly has some concerns, and the agency has issued a draft guidance for industry.
The guidance is designed to assist industry with the development of radio-frequency (RF) wireless technology in medical devices. The 28-page guidance addresses issues and concerns related to the safe and effective use of RF technology in medical equipment. It emphasizes the need for wireless coexistence, performance, data integrity, security, and electromagnetic compatibility (EMC).
Because these issues affect all stages of a product's life cycle, FDA recommends that each of these issues be considered during the identification, documentation, and implementation of product design requirements, as well as during design verification and validation and during risk management processes.
"Wireless devices continue to multiply, and they are becoming more complex with more than one radio technology internal to them," notes Daniel Hoolihan of Hoolihan EMC Consulting in Lindstrom, MN.
According to the guidance, FDA believes the more critical the medical device function and information passed via RF technology, the more important it is that the wireless connection be robust. To protect against electromagnetic interference to other medical devices, FDA is recommending that wireless medical devices limit their RF output to the lowest power necessary to reliably accomplish their intended function.
"The increasing number of wireless devices in everyday use can pose a threat to the safe operation of medical equipment, if proper precautions are not taken in the design and user instructions of the medical equipment," says Roland Gubisch, chief engineer for EMC and telecom at ITS Intertek Semko (Boxborough, MA). "I'm sure this guidance document will help to keep new medical equipment as robust as possible, especially if it alerts designers to interference issues they were not aware of."
FDA recommends that device manufacturers describe in their premarket submissions and in their labeling the wireless technology and RF specifications, the testing performed, and the testing results demonstrating that the wireless functions will operate safely and effectively in the intended environment.
"FDA will certainly emphasize the document in its dealings with RF-related device submissions," says Hoolihan.
Gubisch notes that especially with respect to standards for active implants, standards and draft standards are calling for ever-higher RF immunity test levels. "Of course, the stakes are much higher for such critical or life-supporting medical devices," he says.
The guidance document notes that IEC 60601-1-2:2001, the EMC standard for medical equipment, is exempt from immunity provisions in the passband and, therefore, is currently inadequate to assess whether a wireless link will operate in the presence of in-band electromagnetic disturbance. For example, Gubisch says that recent surveys have shown that perimeter surveillance equipment, electronic article surveillance systems, and RFID readers can generate magnetic fields in excess of the levels set in the existing nonmedical and medical EMC standards.
"I hope that this guidance document, once finalized, will help in the design and evaluation process," says Gubisch. "The document could be expanded, and I suspect it will be as a consequence of the public review process," he says.
