Correspondent: David Gagliano, Principal Investigator, BDM Federal, Inc. dgaglian@bdm.com

A pilot project is testing the feasibility of using wireless telemedicine to compress the time interval between onset of ischemic stroke symptoms and beginning definitive therapy. The project is funded in part by a $500,000 grant from the National Library of Medicine, and by contributions from the U. of Maryland Hospital (UMAB) and BDM Federal, Inc. Project goals are to develop and integrate technology that enables video images, audio, vital signs, and ECG rhythm strips captured from within a moving ambulance to be transmitted over a digital wireless telephone system (Sprint/ American Personal Communications; http://sprintspectrum-apc.com). This information is reviewed in real or near-real time by tertiary center neurologists sitting at workstations in their offices, where they can monitor and manage the patient. Early stroke intervention was chosen for this pilot because "brain attacks" are so debilitating – more than $30 billion/year is spent treating strokes, according to study Principal Investigator David Gagliano – and because morbidity and disability can be significantly reduced if appropriate thrombolytic therapy is given within a ‘golden’ 3-hour period of symptom onset. Currently, only 3% of candidate patients receive thrombolytic therapy due to missing the therapeutic window, he states.

Key to the technical success of the mobile telemedicine project is the tight integration of existing commercial technologies and the use of open-system standards, says Mr. Gagliano, who works for BDM Federal, Inc. BDM, which was wholly acquired by TRW in late 1997, specializes in the integration of off-the-shelf technologies for new applications. The ambulance-based system uses a video system (FoNet, Tulsa, OK; www.firstlook.com) and a patient monitor interface (WestTech Mobile Solutions, Vancouver, BC; www.westechmobile.com) to capture images automatically from a moveable camera in the ceiling of the ambulance, above the patient’s head.

The images are compressed using the JPEG standard and transmitted over the digital Sprint PCS spectrum, using up to 4 ‘bonded’ digital wireless phone lines to transmit the voice, images, and data. Bandwidth is currently limited to about 5 Kbps per phone line, which in turn limits the typical aggregate transmission rate to about 20 Kbps. The wireless signals are transmitted to an NT server at the University hospital. There, using JAVA-scripted instructions, they are ‘pushed’ to the computer monitor of any enabled clinician on the hospital Intranet, where they can be viewed in Netscape or Internet Explorer. A prompt allows the physician to score the patient on the NIH Stroke Scale and to hasten the process of deciding about the proper use of Tissue Plasminogen Activator (t-PA) or other management options. The video images are captured at 30 fps, but because the wireless bandwidth is limited to about 20 Kbps, the images are transmitted in ‘slow scan’ fashion at about 1 image every 2.5 seconds at FCIF resolution (320 bits x 240 lines x 24-bit depth). The technology allows on-the-fly tradeoffs between motion handling and resolution, and a special button allows the emergency personnel in the ambulance to capture specific images or video clips at 5 fps, which can be sent in a store-and-forward fashion. Redundant wireless circuits are available in case the connection is broken. Audio is provided by a standard, analog ambulance radio. Real-time vital signs and ECG tracings can not yet be integrated onto the clinician workstation, but will be soon. Also planned is the electronic integration of the output of a portable blood chemistry analysis machine (i-STAT Corp., Princeton, NJ; www.istat.com) that provides real-time results that previously required waiting for a laboratory workup

The project has been underway for 18 months, with field testing for 4 months, including over a dozen real ambulance patients seen. Stability problems with the Windows 95 operating system are being overcome. Plans are to make the telemedicine interactions available at physician’s homes, and to allow the images and data to be triaged to other tertiary centers. Further in the future, access to Low Earth Orbiting Satellites (LEOS) or improved cellular bandwidth could increase the transmission capabilities to several Mbps.

The project has been helped immensely by the enthusiastic cooperation of ambulance company Maryland ExpressCare, and by the participation of specialists at the UMAB Dept. of Anesthesiology

Research and the UMAB Brain Attack Center, states David Gagliano. More information is available at the project website – http://batcave-express.ab.umd.edu/info.htm.