In Search of Wireless Monitoring

Emergency medical personnel base many lifesaving decisions upon patients’ vital signs. While there are many portable instruments for monitoring pulse and heart rate, oxygen saturation (SpO₂), electrocardiogram (EKG), blood pressure, temperature and respiration rate in the field, they are often cumbersome and must be connected with wires to various physiological sensors. The more medical information needed, the more sensors and wires are required. These wires tether the paramedic to the patient, even when moving up and down stairways and through tight spaces, take up valuable space in ambulances and aircraft, and create potential confusion and entanglement problems.

When the EMS community asked for a technology that would wirelessly connect sensors to a lighter, smaller monitor, the U.S. Department of Homeland Security (DHS) Science and Technology Directorate (S&T) was glad to take up the challenge. Yet we realized we had a lot to learn. Thanks to valuable insights from EMTs, paramedics and other medical personnel across the country, we quickly developed an appreciation of the complexity of the problem and in June 2012 established our Wireless Patient Vital Signs Monitoring project to prototype a solution. 

“The idea,” explains Michael Elconin, contract manager for the project and a former software engineer, “was to sever the wire between the patient and something the paramedic has to carry, and the same in the ambulance: eliminate cables running from the patient to an external device.”

When taking on challenges like this, S&T helps the responder community define operational requirements for the technologies it needs and supplies funding and guidance to technically qualified partners who conduct the research and development. In this case we chose Sotera Wireless, Inc., a start-up company in San Diego, as a partner. Sotera was already at work on wireless vital signs monitoring devices for hospital use. These devices have been installed in a number of hospitals, where they allow nurses to continuously and wirelessly monitor multiple patients from a central location, enhancing safety by enabling early detection of changes in condition.

In developing a wireless vital signs monitoring system for EMS use, Sotera physically ruggedized and operationally modified its hospital device. The new device, named ViSiEMS (Vital Signs Emergency Medical Services), exceeds international medical device safety standards for drop resilience and meets the international standard for water resistance. It has built-in accelerometers to sense when it is moving, and its operating algorithms—mathematical procedures used to sense, calculate and display waveforms—are designed to compensate for motion and vibration in the ambulatory environment.

Field Assessment

In San Diego in early December, a group of highly accomplished responders—EMTs, paramedics, a trauma nurse and hospital physicians—participated in an operational field assessment of the prototype. This included three emergency medical scenarios, including a simulated vehicle accident.

ViSiEMS consists of two components. First is a small touchscreen device (Figure 1) that collects vital signs data via wires attached to sensors on the patient’s body. The device attaches to the patient’s wrist (Figure 2) and displays EKG (3-, 5- or 12-lead), heart/pulse rate, SpO₂, blood pressure (cuff-based and also cuffless on a beat-to-beat basis), respiration rate and skin temperature. ViSiEMS also incorporates a proprietary CAN (controller area network) bus technology, which allows it to collect data from sensors developed by Sotera’s partners.

The touchscreen device also wirelessly transmits information via WiFi to the second component, a remote monitor—in this case, a military-specification Toughbook laptop (Figure 3), the only computer currently approved by the FDA for ambulatory medical use. The laptop serves as a WiFi hotspot, server and remote viewing device for up to eight touchscreen devices simultaneously. FDA approval of other types of monitoring devices, such as tablets and smartphones, is expected in the future.

The ViSiEMS has eight gigabytes of memory—sufficient to store at least 12 hours of data—and the 2014 commercial version of the device will enable physicians at receiving facilities to download this data upon the patient’s arrival, giving them a complete record of the patient’s condition from the time the ViSiEMS was activated. In addition, at any time while at an incident site or in transit, the EMT or paramedic can send a “snapshot” of the patient’s data in a secure PDF to the receiving facility via cellular interface. This enables emergency physicians to review the patient’s statistics (Figure 4) and prepare proper treatment ahead of arrival.

In general, the assessment team was very positive about the ViSiEMS’s performance in the three scenarios. Nonetheless, as with all prototypes, there was room for improvement, and the team provided feedback and recommendations Sotera is addressing before releasing the commercial product. The assessment team also made suggestions for additions and modifications, such as brightly coloring all components to make them clearly visible in the confusion of incidents, incorporating a GPS capability to track patients in transit, and adding on-screen instructions that tell medical personnel how to download data from the device or get technical assistance.

Mass-Casualty Incidents

The longest and most animated team discussion centered on ViSiEMS’s potential in mass-casualty incidents. Each ViSiEMS system can simultaneously monitor up to eight touchscreen devices. Using WiFi, each system can link to others at battery-powered axis points consisting of commercial off-the-shelf hardware. By setting up several such axis points at a casualty collection point, ViSiEMS devices can be used to monitor hundreds of patients simultaneously from a central command post.

With FDA approval of the use of smart device applications in the medical environment, responders will be able to link to ViSiEMS, monitor patients’ vital statistics on their tablets, smartphones and smart watches, and be alerted instantly if those statistics change significantly.

With its ability to link the device and the patient’s triage tag via barcode scanner, ViSiEMS could prove invaluable for avoiding lost data and patient identification errors. This ensures collected data is permanently linked to the patient. And in mass-casualty situations, ViSiEMS’s ability to send ahead snapshots of patient statistics will help receiving facilities properly prepare for casualties.

Although work remains to be done, we are proud of what the Wireless Patient Vital Signs Monitoring project has achieved in 18 months. We anticipate no technical challenges that will prevent FDA approval for ViSiEMS or our bringing a commercial version of the system to market in 2014.

Thanks to everyone involved in the project and especially the emergency responders on the assessment team: Dr. Thomas Burnett, emergency medical physician on the faculty of the Virginia Tech School of Medicine and emergency physician for the Federal Bureau of Investigation Hostage Rescue Team; Anne Marie Jensen, San Diego paramedic and manager of the San Diego EMS Resource Access Program; Jacqueline Kennedy, registered nurse, on active duty with the U.S. Department of Health and Human Services, serving as a trauma nurse with the Rapid Deployment Force; Dr. Robert McLafferty, Children’s Hospital, Pittsburgh, former flight paramedic and trauma coordinator now overseeing county 9-1-1 services; Michael Marsh, captain of the American Medical Response Special Operations Unit in San Mateo, CA, and coordinator of the Northern California Disaster Response Team; Dr. Natasha Powel, emergency medical physician and clinical instructor at Johns Hopkins University in Baltimore; and Torie Wood, Central Joint Fire and EMS District firefighter and paramedic, and EMS and firefighter instructor, Leesburg, OH.

King Philip Waters is program manager of the First Responders Group for the U.S. Department of Homeland Security’s Science and Technology Directorate.