By Paul Kruczkowski, editor
When I hear the words “radar technology,” I (and many other engineers, I would imagine) tend to think about military target or threat identification, air traffic control, marine navigation, weather monitoring, or even the new automotive accident avoidance systems. Using radar for medical diagnostics, such as non-contact monitoring of patient vital signs, is not an association I would immediately make. However, I was intrigued to learn recently that just such a medical radar system is on the verge of adoption in hospitals and other medical centers.
Medical radar has been the subject of research papers and experiments for decades. According to a report published by the Norwegian Defense Research Establishment (a research institute that conducts R&D for the Norwegian Armed forces), the use of radar for medical diagnostics first received serious consideration in the 1970s, to detect organ movements and water condensation in the lungs. The use of continuous wave (CW) radar to monitor heart rate and pulmonary motion dominated research publications in the 1980s, while the 1990s ushered in the use microwave impulse radar for such applications. Pulsed radar advanced the theory of medical radar significantly, since short duration pulses translate to wide bandwidth, and radar bandwidth directly impacts range resolution, thus making it possible to measure both organ movement and range of movement. Since this breakthrough, the focus of study has been on two types of medical radar, CW Doppler radar and impulse ultra-wideband (UWB) radar operating over a wide range of frequencies.
Years of research has finally paid off with the announcement of operational medical radar hardware. On April 30, 2012, Sensiotec Incorporated unveiled its new Virtual Medical Assistant (VMA) non-contact vital signs monitor at the 17th Annual American Telemedicine Association Meeting & Exposition in San Jose, CA. The system utilizes patented UWB, radar to remotely measure heart and respiration rates, as well as patient movement, without the need for implants, electrodes, or sensors that contact the patient. The VMA technology has received FDA 510(k) Class II pre-market clearance to enter field trials, which is a significant step forward for medical radar technology.
Let’s take a look at how the VMA technology works. The system is driven by a lightweight sensor panel that is placed within 5 feet of the patient — above, below, or next to the bed at the hospital or other point of care. This device emits UWB high-frequency, low-power nanosecond pulses that are 20 million times weaker than mobile phone signals yet are capable of producing high temporal and spatial resolutions and ultra-low-power specific absorption, without ionizing radiation. The UWB pulses penetrate the body and reflected signals from the torso, lungs, and heart are detected, separated, filtered, and processed, converting them to medical data on body movement, respiration and heart rates.
The system acquires patient data every two seconds and streams it in real-time on a ZigBee wireless mesh network utilizing scalable client-server architecture. This patient data can be continuously distributed to multiple care givers (doctors, nurses, and/or EMTs) via computer, pager, tablet, or smart phone. In addition, special alerts can be set for patients who experience deteriorating heart and respiratory rates, are in danger of falling, or require pressure ulcer prevention management.
The benefits of this new medical radar technology are numerous. For the patient, they include freedom from wires and sensors, elimination of skin tears from adhesive sensors, and reduced likelihood of bed sores and dangerous falls. Healthcare providers will benefit from reduced monitoring costs (since the system can handle a virtually unlimited number of patients), increased nursing staff productivity (since they won’t have to continuously revisit patient rooms to reconnect sensor leads), and reduced liability costs (from improved patient safety).
The field trails of the VMA system in three southeast medical centers, including an undisclosed Atlanta hospital, are quite an accomplishment for medical radar diagnostics. But, it’s only the first step in implementing a technology that could have a profound impact on medical diagnostics in the future. In fact, several technical papers on the use of medical radar for biomedical sensing will be presented at the International Microwave Symposium (IMS2012) show in June:
It is clear that the research and development will continue and that other medical radar devices are on the horizon. I’m interested to watch this new application for radar technology unfold before our very eyes and ultimately arrive at a hospital near you (and me).