Patient monitoring in the fast lane
News Date:2008-12-10
At Samaritan Medical Center (SMC) in Watertown, N.Y., we needed to continuously monitor patients¡¯ vital signs as we moved them from the emergency department (ED) to radiology. To maintain the monitoring signals, we planned to implement wireless technology, but we had to balance competing data demands across a finite bandwidth within our hospital. Several years of research and development led us to achieve a Wi-Fi solution that prioritizes critical monitoring data from the ED while continuing to service other departments in the hospital.
Traditionally, patient monitoring has required its own separate, dedicated network to guarantee security and performance. Now, using a virtual local area network (VLAN) within our existing network, we can put critical patient monitoring data in the "fast lane," ahead of administrative applications.
From Wired to Wireless
SMC is a 287-bed community medical center that serves as a regional referral center for northern New York. With more than 9,100 admissions annually and 37,500 emergency visits last year, SMC is the largest provider of healthcare services between Burlington, Vt., and Syracuse, N.Y. Our 1,600 employees make us the largest private employer north of Syracuse.
In 1999, we purchased a wired monitoring system for the ED from a business unit of Siemens Medical Solutions that later became part of Drager Medical of Telford, Pa. However, our long-term plan was to improve upon our previous wireless monitoring system and replace the wired system with wireless. Our previous wireless system had used radio frequency (RF) transmission, and although the antennae were correctly positioned throughout the ED and radiology, the lead walls in the diagnostic area caused complete loss of signal when moving patients into radiology rooms for X-rays and scans. The signal was also subject to cellular phone and electrical equipment interference problems.
When Drager Medical came to install the wireless technology for ED monitoring at Samaritan in 2003, they realized that there would be duplication of the wireless access points that the hospital¡¯s IT department was already in the process of installing to support the hospital information system (HIS). Everyone at SMC agreed that the wireless initiative had to happen, but installing two wireless network infrastructures would cause major problems.
Unlike RF antennae, which only receive signals from devices, wireless access points both receive and send information from and to each device. With two access points in the same area, patient monitors or laptops would not be able to lock on to just one. The device would try to "talk" to both access points, bouncing from one to the other, and never be able to transmit its data.
Too Much Traffic
Our IT steering committee, which included senior management and physicians, had to carefully balance different interests throughout the hospital, blending both biomedical and information technologies, and always keeping in mind the bottom line goals of improving patient care while maximizing the use of our existing infrastructure.
The key challenge that we needed to address was that there were too many data applications or "vehicles" potentially trying to use the hospital¡¯s "information highway" (the network). Since we knew we could not simply add new access points to successfully go wireless, the various departments would have to share the bandwidth. Over the course of 2003-2004, through research into standards-based wireless technology and application data traffic management solutions, we determined that patient monitoring and other HIS applications at Samaritan could co-exist. Because this technological feat had never been accomplished before, it took a full six months to get these systems to work together.
The basis of SMC¡¯s solution to our data transport and sharing issues was a VLAN, a network of computers that behave as if they are physically segmented even though they actually share network equipment. VLANs are configured through software rather than hardware, which makes them extremely flexible, allowing network administrators to fine-tune their networks by logically grouping users (in SMC¡¯s case, the ED and HIS). We needed to develop a VLAN specific to patient monitoring inside our existing wireless access point network.
The complete solution, which was later trademarked as Infinity OneNet by Drager Medical, uses an IEEE 802.1 lb wireless protocol. The OneNet technology allows both the HIS and the ED to go wireless at the same time, creating two separate "lanes" in the "information highway," one for the less critical, less sensitive applications data, and one dedicated lane for the patient monitoring data.
After much discussion, we agreed to approach the project as experimental, but with an understanding that the existing HIS would not be disrupted. Although the software was being developed on-the-fly, we could clearly see the potential benefit of combining wireless monitoring and the HIS. Drager Medical made the investment in research and development and, beginning in late summer 2003, brought their consultants onsite regularly to set goals and to work out the technical aspects of the wireless solution. By Match 2004, 10 beds within SMC¡¯s 22-bed emergency department went wireless.
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