It is a classic image: a critically ill patient in a hospital bed connected to various medical devices by wires and IV tubing for monitoring and treatment. These devices are attached to the wall beside the bed and wired into the hospital infrastructure. While this is certainly still a real and necessary role for medical devices, the needs have expanded to include many other locations, roles in patient care, types of devices and connections to patients and devices.
At the same time that the needs for electronic health records (EHR) and increased operating efficiency demand increased device connectivity, the expanded roles and scenarios demand mobility and new types of connections. Wireless technologies have a very clear role in fulfilling these needs now and in the future.
Even though there are medical regulatory challenges for wireless technology, wise use of both draft and released guidance documents and appropriate hazard analysis and mitigation have allowed most companies to receive clearance and approvals for wireless medical devices (See Design for Regulatory Compliance ). Standardized technologies contribute to the understanding of device interactions and can serve to limit some types of testing burden due to their existing compliance testing.
An increasing number of these needs can be filled using commercially available industry standard technologies without the high costs of development and support for custom wireless radio frequency (RF) solutions. Industry standard wireless technologies allow the use of modules that leverage the skills of companies with wireless technology expertise and can contribute to long-term availability and higher reliability solutions.
Many wireless technologies are available for this market and have their unique benefits and challenges. One size doesn’t fit all applications, so it is necessary to understand the best fit for each application. While often multiple technologies can be used, some technologies are better than others in a specific situation. This article presents several scenarios and considerations involved with different commercially available standardized wireless technologies.
Standard Wireless Technologies for Medical Devices
Implementation solutions are available from many suppliers and include chipsets through complete modules, like the Wireless LAN (WLAN) UART Serial Port Module OWS451 from connectBlue.
Many RF wireless technology alternatives are available to medical device designers from custom proprietary solutions to industry standards. The development, testing, radio regulatory approval and technology maintenance of a nonstandard RF wireless solution is a huge undertaking and difficult to justify for medical products. The use of industry standardized technology is a good way to leverage the work of much larger industries and take advantage of economies of scale and the competitive marketplace.
Wireless LAN (WLAN). There are two well-established technologies with proven track records for medical usage as well as a relatively new one with a familiar name. Wireless LAN (WLAN), or IEEE 802.11, has become ubiquitous in IT infrastructure and has an active standards group as well as industry branding and advocacy (WiFi Alliance). The currently used variants include the direct-sequence standards IEEE 802.11 a/b/g/n, which are implemented in the 2.4 GHz (802.11 b/g/n) and 5 GHz (802.11 a/n) ISM bands with different methods for usage of those regions of the RF bandwidth. Wireless LAN provides reliable high-speed implementations and methods for authentication and encryption necessary for medical usage.
Wireless LAN is available in implementations offering trade-offs between cost, data rates and implementations.
Like Wireless LAN, implementations are available from many suppliers and include chipsets through complete modules, like the Bluetooth Serial Port Module OBS421 from connectBlue.
Bluetooth Technology. Bluetooth technology is the second familiar wireless technology in medical scenarios. It is used in diverse nonmedical applications ranging from headsets to heart belts. It also uses the 2.4 GHz ISM band that occupies the same band as is used by wireless LAN, but includes coexistence methods to insure cooperative use of that band.
Bluetooth technology provides lower data rates (see Table I), uses less power than wireless LAN, and has a very robust radio design. The frequency hopping radio provides very strong immunity to RF noise sources such as electrosurgical and common household appliances such as microwave ovens and motors.
The mature standard Bluetooth technology is currently used in medical devices ranging from wearable ECG monitors to external defibrillators.
Bluetooth Low Energy Technology. The new name in town is the Bluetooth version 4.0 which features Bluetooth low energy technology. While it shares attributes from Classic Bluetooth technology like the robust frequency hopping radio and 128-bit encryption, there are differences in implementation. These differences allow for very low power operation for periodic sensor applications where battery lifetimes are measured in months or years.
Table I. The characteristics and differences of the two types of Bluetooth technology are shown in the table below. For an in-depth comparison of the two technology implementations, please see http://www.connectblue.com/technologies/bluetooth-low-energy-technology/#c11591.
Bluetooth low energy technology cannot interface directly with Classic Bluetooth technology, so two implementation types have been developed. The dual-mode implementation can communicate with both types of Bluetooth technology. These are called Smart Ready devices. The lowest power consumption is achieved with pure Bluetooth low energy implementations, called Smart devices. These implementations are single-mode and can only communicate with each other. (For additional discussion of Bluetooth low energy in medical applications, see Bluetooth Low Energy Technology Makes New Medical Applications Possible . For additional information on the differences between Classic Bluetooth and Bluetooth low energy, see Bluetooth Low Energy vs. Bluetooth Classic )
Bluetooth low energy implementations are available from many suppliers and include chipsets through complete modules, like the one shown here, the OLP425 from connectBlue.
Wireless Usage in Hospitals
The hospital environment is often the first one that comes to mind when considering medical devices and technology. Even though the number of beds in U.S. hospitals is not increasing, the need for improved connectivity to implement EHR systems, lower risk, and improve patient care is driving the adoption of wireless technology into more devices.
Monitoring of Unmonitored Patients Improves Safety and Efficiency. Many patients are not monitored and reports rely on manual vital signs entry for their EHR needs. This manual process results in increased workload and potential issues from unmonitored patients or transcription errors.
Connectivity opportunities include using patient entertainment systems (video and audio) for education and information about medical procedures and follow-up processes.
The potential hospital hub diagram represents a flexible configuration as a bedside connectivity hub can meet the connectivity needs utilizing appropriate standardized wireless technologies.
Patient Bedside: Wireless Bedside Hub. Since Wireless LAN (IEEE 802.11 a/b/g/n) is the most widely deployed connectivity infrastructure in hospitals today, it is the preferred choice for the connection to hospital IT systems including EHR. The currently deployed standards are primarily 802.11b/g at 2.4 GHz, but many installations have expanded to utilize 802.11a and 802.11n (at 5 GHz) to take advantage of the increased number of unique channels offered in the 5 GHz bands.
Bluetooth technology provides for local connectivity to patient connected and data collection devices. The frequency hopping technology with adaptive features (adaptive frequency hopping, or AFH) allows for coexistence with wireless LAN and Bluetooth technology uses less power, which is particularly beneficial for battery-powered and mobile, handheld devices. Classic Bluetooth technology is used for higher data rates and streaming devices, and Bluetooth low energy technology gives longer battery life to intermittent and lower duty-cycle patient worn sensors.
The connectivity hub handles traffic and protocol conversions and coordinates between the connectivity technologies. An embedded compute engine based on Linux or a similar high-reliability embedded or desktop operating system can provide connectivity hub functionality.
Wireless Usage in Day Surgery and Clinics
An area of growth for patient care is the clinic or outpatient facility. Improved patient care at lower costs provides incentive for hospital systems to add these treatment options instead of adding new beds to traditional hospitals.
Wireless Incentives. Flexibility, efficient resource utilization, and integration with the EHR are strong drivers for wireless adoption in these day surgery and clinics. The wireless advantage for these facilities is increased efficiency to handle the most common procedures and deliver the same or improved patient care and outcome. Key communication features support tightly integrated electronic records for documentation and patient billing systems. Wireless technology offers superior flexibility and connectivity opportunities.
The diagram illustrates a potential implementation for an infusion pump as the central hub for a flexible small monitoring system for relatively minor medical procedures.
Flexible Simple Pole-mounted Monitor Infusion Pump Hub. In this scenario, the infrastructure and needs are very similar to those of the hospital scenario; however, the connectivity hub in this scenario is mobile, rather than fixed. In the infusion pump scenario the connectivity moves with the patient instead of being located with a bed to provide for improved mobility and flexibility.
Wireless LAN is the best choice for electronic records connectivity, while Bluetooth technology is the best choice for local device interfaces focused on coexistence, mobility, and low power for potential battery operation. While the device and communication needs are similar, the infusion pump scenario typically supports patients and procedures of lower acuity and has lower demands for complex patient monitoring parameter.
Wireless Usage in Emergency Medical Systems (EMS)
Emergency care is an essential component of the patient care continuum. Whether for civilian or military environments, the needs are for a rugged and very mobile battery powered patient monitor. Wireless technologies are key to meeting those requirements.
Mobility and Connectivity Enable Better Information Flow. Wireless technology provides local connectivity for sensors, eliminates cabling that can interfere with patient care in time-critical situations, and provides for mobile connectivity solutions for hospital emergency staff. Data collected during treatment and transportation can be downloaded and reviewed to improve the system for the future.
Transport Monitor. A rugged patient monitor would use Bluetooth low energy technology to provide for patient-connected devices that transmit data periodically. The frequency-hopping radio provides robust radio connection in RF-noisy environments such as vehicular or industrial accident scenes.
Classic Bluetooth technology offers an equally robust solution but is best suited for needs of higher data rates, data streaming connectivity, and a common interface for smartphone and tablet devices that provide WAN connectivity and rich user interface capabilities.
A rugged patient transport monitor that utilizes Bluetooth low energy technology.
Aging in Place
As our population ages, it becomes increasingly important yet more difficult to provide for safe environments for that population that minimizes the burden on our healthcare resources. The demand will outpace the supply of these critical resources going forward without simple, efficient and low cost systems.
Low Cost Monitoring of Daily Healthcare. Bluetooth low energy technology and home network connectivity provide the building blocks that allow older people to safely stay in their homes by monitoring daily living. The home environment can be very challenging to RF technologies since buildings are not standardized; walls can reduce transmission capabilities and common home appliances can interfere with technologies like Wireless LAN. Bluetooth low energy technology provides a robust technology at a price and power point to allow several data collection points to be spread throughout the home and networked through a power line or other robust, low cost networking technologies.
Very simple devices allow remote caregivers and family to monitor basic activities and can alert them to changes or missed medications. Standard low-cost consumer devices provide for fundamental needs like medication monitoring and activity, while a simple scale provides weight to offers weight to monitor food intake and fluid retention. Proximity sensing provides location information alleviates concerns about wandering or mishaps outside the home environment.
Aging-in-Place Support. The standard profiles for Bluetooth low energy technology provide for necessary functions such as weight, heart rate, and proximity monitoring. The connectivity solution also offers mobility through appropriate applications on a smartphone for use outside of the home.
The home hub connects devices with the Internet so that family and caregivers can follow activities and provide support with confidence.
The diagram outlines a system for support in the home environment. Depending on the person's needs, different devices outlined on the bottom row would be selected to provide appropriate data collection and monitoring. Many of these will be available shortly in consumer devices.
The standardized wireless technologies Wireless LAN, Classic Bluetooth technology, and Bluetooth low energy technology provide for the communication and connectivity needs for many medical device needs. These technologies can be used as tools to solve connectivity issues associated with real-world implementation of medical devices.
The wireless technologies offer much more than cable elimination. They provide the keys for safe and effective solutions for the vital linkages necessary for EHR as well as remote care and diagnosis.
Bill Saltzstein is the president of connectBlue Inc. as well as the medical business development manager, with more than 25 years of experience in medical device development and wireless technology.
Prior to joining connectBlue, Saltzstein worked as a wireless medical expert through his own company, Code Blue Communications, and served in product management and development positions at Medtronic Physio-Control, Instromedix, and Hewlett-Packard.