Wireless Medical Devices: Navigating Government Regulation in the New Digital Age

We have come a long way since the health care industry’s only reliance on wireless technology was the ability of doctors to wear beepers on the golf course.

The ongoing revolution in wireless communications today has the potential to dramatically change the nature of many medical devices and the delivery of health care services, while improving care and lowering costs. Patients who rely on such devices no longer need to be tethered to a tangle of cables, enabling physicians to obtain vital information on a real time basis without the need for office visits or hospitalization.

Some wireless devices are implanted and used, for example, to control bodily functions such as heart rhythms or nerve stimulation or to monitor cranial pressure. Other wireless devices are worn on the body and used, for example, to measure and report on an array of physiological conditions such as body temperature and other vital signs or assist the movement of artificial limbs. Wireless devices can even be incorporated into pills themselves to monitor patients’ compliance with their dosage regimen. Whether implanted, worn, or ingested, wireless medical devices offer the prospect of greatly improving preventative, therapeutic, and managed care.

As microprocessors become smaller and more powerful, the development of an even wider array of wireless medical devices is inevitable, and presents an exciting opportunity for device manufacturers to develop new products that can be an important part of driving down the cost of health care. However, in order to bring wireless medical devices to market, manufacturers must understand the regulations of both (1) the Food and Drug Administration and (2) the Federal Communications Commission which regulates use of the radio spectrum. Compliance with one agency’s rules does not necessarily guarantee acceptance by the other.¹Manufacturers may also wish to consider whether the Centers for Medicare and Medicaid Services within the U.S. Department of Health and Human Services (or one of its contractors) would determine that a new device provides “reasonable and necessary” care for reimbursement purposes, which may be crucial for the commercial success of the device. Medicare currently provides coverage for medical devices and services for over 43 million beneficiaries.

This dual federal regulatory structure means that manufacturers are required to navigate myriad technical rules and policies enforced by agencies with different, and perhaps divergent, objectives. Unless these regulatory issues are taken into account at the earliest stages of research and development, device manufacturers could find themselves investing significant time and resources in products for which they cannot obtain government approval. Failure to comply with applicable regulations can result in government investigations, fines, forfeitures, and other penalties, which in turn can lead to civil litigation and shareholder lawsuits. Intentional non-compliance can even result in criminal charges against corporate officers.

FDA Regulation of Wireless Medical Devices

Unlike the FCC, the FDA does not have specific technical requirements for wireless medical devices, but rather the device must either be found “substantially equivalent” under the 510(k) program or safe and effective under the PMA program (assuming it is not a Class 1 device exempt from FDA marketing authorization requirements). For example, “panic buttons” that are worn on the body and allow a person to place a telephone call remotely to an emergency response center are regulated by the FDA as “powered communication systems,” but are exempt from the 510(k) program. An “ingestible telemetric gastrointestinal capsule imaging system” used to detect abnormalities of the small bowel, consisting of an ingestible capsule containing a light source, camera, transmitter, and battery, requires 510(k) authorization. An implantable pacemaker that utilizes telemetry for the relay of information and instructions is an example of a Class III device that requires a PMA.

In 2007 the FDA released a detailed draft guidance on “Radio-Frequency Wireless Technology in Medical Devices.”²Available at http://www.fda.gov/MedicalDevices/DeviceRegulationandGuidance/GuidanceDocuments/ucm077210.htm. For devices incorporating software, as often occurs with devices utilizing wireless technology, the FDA has a separate guidance document available at http://www.fda.gov/MedicalDevices/DeviceRegulationandGuidance/GuidanceDocuments/ucm085281.htm. This document represents the FDA staff’s thinking on the scope of information that should be included in a 510(k) or premarket application for a device incorporating wireless communications technology. As a draft guidance document, it may be that not every recommendation needs to be followed for every device. However, the document is the best reference source currently available for determining what issues should be addressed in a market authorization application, and manufacturers should familiarize themselves with it and follow the recommendations as much as possible.

As stated by the FDA, in general a wired connection is more reliable than a wireless connection. The FDA believes that the more critical the medical device function and information transmitted via wireless technology, the more important it is for the wireless connection to be “robust,” especially considering that wireless emissions from one product or device can affect the function of another and that the use of the spectrum in health care settings is increasing. To protect against electromagnetic interference to other medical devices in the vicinity, the FDA recommends manufacturers limit the output of wireless medical devices to the lowest power necessary to reliably accomplish their intended functions.

The FDA’s guidance covers the following areas:

•
Risk Management
: In considering the risks associated with wireless technologies, manufacturers should focus on (a) electromagnetic compatibility and performance of wireless functions, (b) wireless co-existence, (c) quality of wireless service, (d) integrity of data transmitted wirelessly, and (e) security of data transmitted wirelessly and overall network access.

•
Design and Development
: Manufacturers should address issues such as how users will interact with the system, environmental requirements, ability to handle interference, and back-up functions, among others.

•
Design and Development Verification
: Manufacturers should implement proper testing to verify the device’s performance.

•
Design and Development Validation
: Devices should be validated under actual or simulated use conditions.

•
Labeling
: Labeling should include, for example, equipment specifications, warnings about possible interference sources, and telecommunications testing results.

•
Purchasing Controls and Acceptance Activities
: Manufacturers should have procedures and controls for all system components, including off-the-shelf subcomponents.

•
Corrective and Preventative Action
: Manufacturers should consider potential problems over the entire life cycle of the device and establish procedures to handle such problems as they arise.

•
Servicing
: Devices should be capable of being serviced while maintaining the integrity of the wireless functions.

The FDA’s guidance refers to numerous standards for manufacturers to consult in designing wireless medical devices. These documents are typically very technical and require sophisticated engineering expertise to properly interpret and implement.

FCC Regulation of Wireless Medical Devices

Every medical device that uses wireless communications technology, whether implanted, worn on the body, or ingested, falls within the FCC’s authority to manage the electromagnetic spectrum.³The FCC also has separate regulations governing “industrial, scientific, and medical” equipment, which apply to medical devices that “generate and use locally [radiofrequency] energy … for medical … purposes … excluding applications in the field of telecommunication.” Medical devices such as MRI, ultrasound, and medical diathermy machines are covered by these rules. However, by definition these devices do not use radiofrequency energy for the purpose of communications, and thus the FCC’s regulation of such devices is generally beyond the scope of this article. Under FCC rules, wireless devices must be tested for conformance to various technical standards and authorized before they may be imported, marketed or operated in the United States. The FCC’s main goal is to ensure that wireless medical devices, like all other products utilizing radio frequencies, operate compatibly with other spectrum users. At the same time, the FCC is trying to accommodate the increasing demands of the health care industry for spectrum where devices can operate without interference.

Short Range and Long Range
Wireless Medical Device Technologies

Generally, wireless medical devices fall into one of two informal categories, short range or long range. As the names imply, s
hort range technologies transmit data to/from the patient utilizing a nearby receiver/monitor (which may itself be connected to additional devices or monitoring locations) for monitoring, control, and diagnostic use, whereas l
ong range technologies generally transmit data to a remote monitoring location.

Available and emerging technologies and FCC services for short range communications include:

•
Inductive Implants: One of the earliest types of wireless medical devices, inductive implants are now in wide use where transmission of large amounts of data and feedback at regular intervals is unnecessary, such as for monitoring (and perhaps controlling) heart function, intraocular pressure, bladder pressure, or cranial pressure. Most devices operate in the bands below 200 kHz. Inductive devices allow for the use of very small antennas and generally exhibit very low energy consumption. Typically, information from the implanted device is accessed by means of a wand-like device placed close to a patient to establish the inductive communication link. Data from the implant can then be read and the implant can be programmed based on patient need.

The principal problem with implants that communicate by inductive link is that data rates are very low. As a result, the wand “reader” has to maintain contact with the patient for long periods of time. In a therapeutic setting, lengthy data transmissions can compromise patient care. Moreover, any movement by the patient or the reader can interrupt the session which may then have to be repeated. Another problem with inductive devices is that there is no international harmonization of frequencies, of particular importance for patients who travel, since monitoring equipment that activates an implant might not be available outside the United States.

•
Medical Device Radiocommunication Service (formerly “MICS”)
: Originally allocated by the FCC in 1999 as the Medical Implant Communication Service for licensed communication between body implants and a nearby controller, the FCC added more frequencies to this service in 2009 for use by body-worn monitoring devices. These devices operate in the 401-406 MHz band at distances up to about three meters. Although a licensed service, it is “licensed by rule,” meaning that no individual application needs to be filed.

MICS technology offers advantages over inductive implants. The frequency band is particularly suited for tissue penetration at relatively low power which helps extend battery life. Readings may be taken from body-worn or table-top transceivers without the necessity of maintaining reader contact with the patient. Further, the higher frequencies enable transmissions of data at much higher rates. European standards for implanted medical devices in the MICS band are consistent with the FCC’s rules.

In 2009, the FCC amended its MICS rules by adding two “wing bands” of spectrum for use by body-worn monitoring devices that do not communicate with implants. The entire service was re-named the Medical Device Radiocommunication Service (“MDRS”). Because of the very low power limits, it is anticipated that body-worn devices in the wing bands will be used primarily for non-critical applications such as monitoring of temperature, pulse rate, and other vital signs that do not require continuous monitoring to sustain life.

•
Medical Micropower Networks: The FCC is considering allocating new spectrum to accommodate operation of implanted microstimulator devices that might lead to the creation of an artificial nervous system that could restore mobility to paralyzed limbs. Under the proposed rules, devices would be “injected” into the body to form a network that would be coordinated by a portable, external master control unit. This network could serve as an artificial nervous system to restore sensation, mobility, and other functions to paralyzed limbs or malfunctioning organs.

•
Medical Body Area Networks: The FCC is also considering allocating new spectrum to allow a wireless “personal area network” of multiple body sensors to monitor or control patient functions. This networking system would not involve implanted devices, but rather could be created through attachment to the patient of multiple, inexpensive, wireless sensors or network nodes at different locations on or around a patient’s body to supply readings such as temperature, pulse, blood glucose level, blood pressure, respiratory function, and other physiological metrics. All this information would be transmitted to a hub that is either worn by the patient or located nearby. The hub could be equipped to initially process the information and then transmit it to a central location. Essentially, the MBAN system would be a way to collect data from multiple sensors, process the data, and then send it to a monitoring station. By creating the network, information that might otherwise be transmitted on separate, possibly conflicting, frequencies can be “bundled” and transmitted on a single frequency.

•
Unlicensed Bluetooth and Zigbee: Although these unlicensed technologies are commonly used with cell phones, handheld devices, and personal computers, they also can be used for implanted or body-worn medical devices. These devices operate in the 902-928, 2400-2483.5 and 5725-5850 MHz bands at distances of 30-60 meters. These technologies are designed for low-power, short-range transmissions. Bluetooth was designed specifically as a replacement for cables between computers and computer peripherals, but it can also be used to monitor implanted or body-worn medical devices. Zigbee was designed to control and automate a network of products and is capable of monitoring groups of implanted medical devices. Each technology has variable power levels and data rates.

A new wireless medical standard, IEEE 802.15.6, is also under development. Although there are no specifications yet, it is intended to be used for a personal area or body area network on a low frequency, with very short range (probably less than 10 meters), longer battery life, and high data rates. Proponents anticipate that the technology will be used for a very small unobtrusive body-worn device for the exchange of medical information between an implant and a wristwatch receiver.

•
Ultra-Wideband: New uses of unlicensed ultra-wideband technologies are starting to emerge for medical telemetry and imaging applications. These devices operate at very low power in almost any region of the spectrum at distances up to a few meters. Because they can transmit large amounts of data, UWB imaging devices can be used to create extremely sharp images of bones and internal organs. UWB devices are also able to detect motion and over a very short range (less than 1 meter) can be used to measure heart rate, respiration, and patient body movement. In addition, UWB devices can be used for very high data rate communications, which makes the technology potentially useful for medical applications that involve large file or database transfers.

•
General
Unlicensed Devices: Other wireless medical devices operate in unlicensed spectrum not limited for medical purposes. For example, “panic buttons” for the elderly are designed to comply with the same rules that govern the operation of garage door openers or home security systems. However, even these devices must meet specific FCC technical requirements.

Available and emerging technologies and FCC services for long-range communications include:

•
Wireless Medical Telemetry Service (“WMTS”): Before the 1990s, remote medical telemetry devices were generally limited to basic heart monitoring. Sensors were placed on the patient’s chest to pick up electrical signals from the heart. These sensors were connected to transceivers by short cables. The transceiver relayed the signals to a central nursing station, often through repeaters installed in the ceiling. The system worked reasonably until 1998, when the first digital television trials in Dallas, Texas utilizing frequencies that previously had not been used in the area for broadcasts began to interfere with the monitoring equipment at Baylor University Hospital. Fearing that interference to heart monitors might become a national medical problem, the FCC immediately started a proceeding to allocate dedicated spectrum for wireless medical telemetry, resulting in the Wireless Medical Telemetry Service.

As stated in the FCC’s rules, the WMTS is for “the measurement and recording of physiological parameters and other patient-related information via radiated bi-or unidirectional electromagnetic signals.” WMTS systems usually function by direct attachment to body sensors or through connection to a short range communication system such as MICS. Eligible licensees (essentially medical professionals) may use WMTS devices without the formality of a license application. Depending on its location, a WMTS system typically has a useful range of 30-60 meters.⁴The FCC has also set aside licensed “public safety” frequencies that may be used for medical telemetry. These frequencies may be used by medical personnel, hospitals, and ambulance services for the transmission of medical information. A system operating under these rules generally consists of both fixed and mobile stations, such as for the transmissions between ambulances and hospitals. It is doubtful, however, that equipment that operates under these rules would be deemed a “medical device” by the FDA.

•
Wi-Fi: In 1997, just before the FCC began its efforts to establish the WMTS, the Institute of Electrical and Electronics Engineers adopted the first version of the 802.11 wireless LAN standards for systems operating in the FCC’s Industrial, Scientific, and Medical (“ISM”) band at 2.4 GHz. With arguably comparable range as WMTS (about 30 meters), Wi-Fi became an immediate competitor, used for transmitting signals from a transceiver to a central nurse’s station (or some other point in a hospital). Subsequently other versions of the 802.11 standard were approved (802.11a, b, g, and n) offering greater ranges and different data rates. The equipment associated with wireless LANS has become inexpensive and reliable and the once-feared interference from other unlicensed devices has not materialized. Further, Wi-Fi systems are considerably less expensive than WMTS systems and, because of worldwide standardization, easier to upgrade with various vendors’ devices. There is an ongoing debate as to whether devices using WMTS or 802.11-based devices will ultimately be the most successful for long range medical telemetry.

•
WiMAX (“World Interoperability for Microwave Access”): WiMAX, generally operated at 2.5 GHz, can transmit over considerable distances, with both fixed and mobile operations. On a small scale, WiMAX can be a direct competitor to the Wi-Fi LANS that are prevalent in many hospitals. With its large bandwidth and speed, WiMAX can transmit monitoring and diagnostic data from multiple patients without the delays inherent in low bandwidth transmissions. Only a few small WiMAX base stations are needed to cover an entire building. In larger applications, WiMAX is capable of area-wide service, connecting hospitals in a region and enabling the sharing of patient information. In its mobile form, WiMAX can be used to transmit patient data between an ambulance and a hospital.

To date, however, WiMAX has not proven as prevalent as its developers envisioned. In hospital applications it must compete with the entrenched Wi-Fi systems. In larger applications, WiMAX’s network architecture requires multiple access points and thus faces the same zoning difficulties that can inhibit coverage for cellular technology. Further clouding WiMAX’s future is the advent of 4G technology which also promises bandwidth, speed, and ubiquity, and relies on existing infrastructure.

FCC Regulatory Requirements for Wireless Products

FCC regulations specify permissible frequencies, power levels, duty cycles (the fraction of time that a system is transmitting), band sharing, and frequency stability requirements, along with detailed test procedures for measuring these parameters. Almost every type of wireless transmitter must be “certified” for compliance with FCC rules before it can be imported or marketed in the United States,⁵When advances in medical treatments are combined with wireless radio technologies, the FCC’s technical rules will often lag behind. In such cases, it may be possible to obtain a “waiver” of the existing rules, or even petition the FCC to develop a new body of rules for the new technology. which involves:

•
Testing: The device must be tested to show compliance with relevant FCC technical standards by an FCC-authorized laboratory, and the test report together with an application form, photographs and other information must be sent to the FCC for approval. Alternatively, a manufacturer may choose to have its application and test report approved by a Telecommunications Certification Body (“TCB”), a private company authorized by the FCC to grant certification applications. Compliance with the FCC’s technical standards is not as black-and-white as one might suppose, as there are often disputes between manufacturers, test laboratories, and the FCC as to whether a given standard is applicable or the appropriate measurement procedures for determining compliance.

•
Radiation Exposure: The device, whether implanted, body-worn, or ingested, must be tested for compliance with the non-ionizing radiation exposure limits of the FCC’s rules. The limits are based on criteria published by the American National Standards Institute for localized specific absorption rates (SAR) in tissue. Compliance can be shown by computational modeling or laboratory measurement techniques. The measurement techniques require specialized equipment and expertise. TCBs are excluded from evaluating SAR testing.

•
Device Labeling: If the device is unlicensed under Part 15 of the FCC’s rules (e.g. Bluetooth, Zigbee) it must be labeled in language mandated by the FCC to inform the user that it is an unlicensed device that is not protected from interference.

Conclusion

The explosion of wireless communications technologies has opened a new era of medical device development. Compliance with the FCC’s technical standards must be achieved in the design of any device – though if that proves to be impossible, perhaps a request for a rule waiver or a petition for a new rule should be considered. On the FDA front, manufacturers should carefully evaluate the availability of prospective predicate devices, and in appropriate cases discuss their devices with FDA staff to determine the best regulatory path forward. How flexible the FDA is in accepting new devices as “substantially equivalent” to predicate devices that may not use the same technology, and how skillfully the case for substantial equivalence is made, will have a large impact on the speed to market for many devices.