Tim Gee, Principal at Medical Connectivity Consulting and the chair of the Medical Device Connectivity conference in Boston last week laid out the market opportunity for wireless sensors in healthcare. Gee broke down some of the drivers for the recent interest in medical sensors, outlined use cases and dissected the market for the more than 200 attendees at last week's event.
What is driving interest in wireless sensors for healthcare?
Gee listed the big drivers for increased interest in wireless sensors for healthcare as: advancements in circuit design and the availability of SoC (system on a chip); device virtualization: if we can push more functionality into the network, it means less needs to be built into the device; advances in infrastructure to support wireless data on carrier networks as well as advancement of WiFi in hospitals; better workflow architectures, like engine-oriented software architectures.
Unwiring the hospital bed
Why should hospitals consider switching from telemetry cables to wireless sensors? Replacing cables with wireless sensors could reduce the potential for infection. Telemetry cables are reused, which means they need to be cleaned and maintained -- a real hassle for some facilities. Wireless sensors, on the other hand, could have a lower cost and may even be disposable in some cases -- no cleaning required. That's a lot of convenience for health providers, Gee noted.
Ambulatory market vs. acute care market
Of course, wireless sensors used inside the hospital's four walls are not as widely discussed as the emerging market for wireless sensors coupled with devices and applications for chronic disease management or fitness metric tracking. Gee breaks the wireless sensing market for healthcare into two distinct categories: acute and ambulatory.
Ambulatory market spearheaded by Continua
The ambulatory market for wireless sensors is the one largely coordinated by the Continua Health Alliance, Gee said. Continua is a multi-vendor alliance that includes providers like Partners and Kaiser as well as manufacturers and network providers. The group has more than 200 members now. Continua focuses on guidelines for personal health products, including those using wireless sensors.
The ambulatory market for wireless sensors includes implantable devices, glucometers & pumps, ICDS, ambulatory diagnostic testing, chronic disease management, weight scales and even MEMS technologies. Ambulatory sensing devices provide clinicians with data over time that they can use to catch chronic disease patients with an intervention long before they have to be admitted to the hospital, Gee said.
CardioNet: Beats the ambulatory drum loudest
From an adoption standpoint, CardioNet's wireless remote cardiac arrhythmia system is the most successful example of an ambulatory wireless sensor product, Gee said. CardioNet's system is made up of a sensor that gets connected via wires to electrodes that collect ECGs. Those then communicate with a large PDA-like device that the patient wears. Gee calls that device the "gateway" since it connects the system to the wireless carrier's network. CardioNet runs on Sprint's network, but it uses a provisioning and management tool from Qualcomm that enables CardioNet to turn on and off the radios in its wireless sensor products. Gee said that the provisioning tool also allows CardioNet to see if a cell tower in the Sprint network is down, so they can better manage their patients.
Acute care lack industry leadership
While the ambulatory market has a clear, leading alliance of companies driving interoperability and innovation, unfortunately, no one group seems to be focuses on wireless sensors for acute care settings, Gee noted.
That said, the acute care market for wireless sensors is much more straightforward: Telemetry applications are the big use cases and a couple hundred thousand of them are purchases in the U.S. each year. Gee said that in some cases, however, these are not bought for use as conventional cardiac telemetry units, they are purchased to be used as low cost wireless patient monitors. That's mostly because there is not a more appropriate monitor on the market today.
Anatomy of a wireless sensor system
A wireless sensor system for healthcare typically has four integral parts: the sensor(s) itself, a body area network (BAN), a server application, a gateway device or a fixed hub, Gee explained. The sensors acquire physical data, but they can either continually transmit this stream of information, transmit at designated intervals or only report when certain events occur. The body area network usually has a range of 3 meters and connects the sensors to the gateway device or bridge and sometimes to each other. Continua Health Alliance has suggested Bluetooth Medical Device Profile and ZigBee Medical Device Profile for BAN protocols in healthcare. The server application is where the data is transmitted to and it may be an online web portal, personal health platform or electronic medical record.
The gateway vs. the bridge
Another way to break down wireless sensor systems for healthcare is by whether they depend on a gateway device or a fixed wireless hub, which Gee calls a bridge. In the gateway model, the patient wears the device, which may be a phone, smartphone, PDA or just a wireless-enabled device. The device may connect to a facility's WiFi or WLAN network or to the carrier network. The bridge is fixed, much like a WiFi access point in a facility. The patient's wireless sensors transmit their data to various sensors as they roam around a facility.
The clinician's perfect world for wireless sensors, Gee said, was a sensor that just peeled off and stuck onto a patient's skin with no other devices needed.