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The newspaper of The Johns Hopkins University November 27, 2006 | Vol. 36 No. 12
Mock Disaster Exercise Tests APL Patient-Tracking Technology

By Kristi Marren
Applied Physics Laboratory

A team at the Applied Physics Laboratory has developed and recently demonstrated new technologies that would automate patient monitoring and tracking during emergency situations, such as a mass casualty disaster, enhancing medical personnel's ability to care for a larger number of patients.

Through a $3 million grant from the U.S. National Library of Medicine, the National Security Technology Department's Systems Concepts and Analysis Group developed the Advanced Health and Disaster Aid Network of electronic devices used to monitor and track patients and to display vital information to users in facilities such as hospitals and in incoming ambulances.

"For years responders have performed these critical tasks with paper triage tags, clipboards of notes, phones and hand-held radios," said APL's Tia Gao, project manager. "This work flow has proven labor intensive, time consuming and prone to human error. AID-N is the only technology of its kind that automates the entire tracking process for providers, vehicles and patients."

Algorithms developed by the team enable the devices to continually monitor a patient's vital statistics and alert a responder when immediate attention is required. Using a digital assistant-like device with embedded camera and Blue-tooth scanner, responders can quickly record a patient's identification information--often by simply scanning the barcode on a driver's license--and look at triage details, treatments, photographs and real-time sensor readings.

"This greatly improves the process of reassessing patients," Gao said.

Using sensors that communicate on a wireless industry standard known as Zigbee, the electronic tags transmit data to GPS-equipped laptops installed inside ambulances, at care facilities and at designated areas of a disaster site.

The project recently culminated in a mock disaster exercise held at Blair High School in Silver Spring, Md., in collaboration with the Montgomery County Emergency Medical Services group and Bethesda-based Suburban Hospital. The scenario--a large school-bus accident--was developed by the National Security Technology Department's Marty Sikes, who develops outbreak scenarios for APL's ESSENCE epidemic-tracking program, in coordination with the Montgomery County Department of Homeland Security.

The patients were tracked by two teams of responders, one using the current paper-based triage method and the other, the electronic devices. One incident commander manually tallied the number of patients from each team, alerting the hospital to the number being transferred. The hospital and ambulances, both outfitted with the team's monitoring equipment, could track patients' locations and medical status using a Web site.

"During the drill, the incident commander miscounted the number of patients being sent to the hospital, but the hospital, monitoring actual data on the Web site, realized fewer patients were incoming," Gao said. "This helped them provide adequate care without overallocating hospital resources."

Other members of the APL-led national team included researchers from Harvard University, who developed the software mesh networking capabilities that run the triage tags; the University of Maryland, who developed software for the devices; and the University of Virginia, who designed the tag hardware.

Suburban Hospital, The Johns Hopkins Hospital and a collection of emergency medical services groups from Baltimore, Montgomery and Arlington counties helped define user requirements and review prototypes, in addition to providing personnel and ambulances for the drill.

APL's team is now preparing a report to be published by the National Library of Medicine and is seeking funds to support further technology development efforts, such as modifying the sensors to detect hazardous chemical or biological agents.

For more about the AID-N project, go to


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