How Do I Find Thee? Let Me Count the Ways

July 1, 2008

There’s more than one way to locate people and objects in hospitals. The best choice depends on the need.

Real-time location systems (RTLS) have become common in today’s hospitals, surgical centers and nursing homes, resulting in cost savings and improved efficiency. From finding key assets in the ED, to optimizing patient flow, to automated billing, RTLS can deliver real benefits across an organization.

There’s more than one way to locate people and objects in hospitals. The best choice depends on the need.

Real-time location systems (RTLS) have become common in today’s hospitals, surgical centers and nursing homes, resulting in cost savings and improved efficiency. From finding key assets in the ED, to optimizing patient flow, to automated billing, RTLS can deliver real benefits across an organization.

However, the plethora of technologies, and their sometimes significant price tags, can be challenging for hospital decision makers, especially when budgets are spread thin. Which technology should you choose? What is the best balance between performance and cost? Which will grow with you as your systems expand and diverge?

How Does It Function?

Typical real-time location systems include: Ultra-wideband (UWB), Wi-Fi, Zigbee and UHF (generally 433 MHz and 915 MHz), and they all work in essentially the same manner — tags attached to objects emit signals to a network of receivers, usually located on walls or in ceilings. Each receiver calculates the distance of the tag from the receiver’s location, and by combining the distances from several receivers, the system determines the location of each tag, similar to the way a GPS device “listens” to several satellites when calculating a position.

There are two classes of RTLS technologies: those that use signal strength to determine the distance to a tag (the louder the signal, the closer the tag), and those that use time-of-arrival (the sooner the signal arrives, the closer the tag).

Time-of-arrival systems are more accurate than signal-strength systems. Consider the cell phone: The signal strength increases or decreases depending on the distance from the phone to the cell tower. It also decreases when moving from outdoors to indoors, or when rotating the phone, and even when the wind blows in the wrong direction (or so it seems). The point being, many more things than distance affect signal strength. Thus, systems that calculate distance based solely on signal strength are less accurate than systems that measure time-of-arrival. Why is timing more accurate? Signals travel at the speed of light no matter what, so the only thing that affects the time-of-arrival is distance.

The only time-of-arrival systems currently in use in healthcare environments are UWB, so most RTLS use signal strength, including Wi-Fi, Zigbee and UHF. Ultrasound is sometimes used; however, it doesn’t penetrate walls, so for a receiver to “hear” a tag, it must be in the same room.

How Do We Use It?

What does all this mean in practice for a healthcare organization? How accurate is accurate enough? That depends on your needs. Reasons for deploying a location system and the technologies required include:

Is a person or object in the building? This is not really a location problem, even though “inside the building” is a location. The technologies used here tend to be passive RFID tags, such as those in ID badges that cause doors to open based on proximity.

In which part of the building is a person or object? Determining approximate locations, such as whether a patient is in the ED or the OR, or, where the wheelchairs are located, requires an accuracy of only 10 to 20 feet, which signal-strength systems can achieve. However, determining the exact locations of persons and objects so they can be quickly retrieved requires accuracy of better than 10 feet, which some signal-strength systems can deliver, but often not reliably. This is the edge where time-of-arrival systems become necessary.

What is happening to a person or object? How people and things are interacting, is the most highly valued location information. For example, which bed does patient P occupy, or with whom is doctor D consulting? Which of two patients in room A is using the vital-signs monitor? How long has patient E been waiting in the ED? This level of information requires location accuracy better than three feet, and preferably as good as one foot, with high reliability. Currently, UWB time-of-arrival systems are the only type able to provide this information.

Hospital organizations can have the most precise, highest-value location information available by installing UWB RTLS solutions throughout their facilities, and some have, even though the initial investment can be higher than signal-strength systems. However, some hospitals that need a lower cost of entry into the world of RTLS may be required to compromise on accuracy (and therefore value).

The reason accuracy may be compromised is because specific tags are generally only “heard” by specific receivers. These “single-mode” systems require that the same type of RTLS be installed throughout the buildings, so that the tags can be tracked throughout the entire organization. However, various locations within a hospital might have different RTLS needs. For example, interaction-level accuracy might be critical in the ED or OR, where process efficiency has a positive impact both on quality of care and top-line revenue. While deploying disparate locations systems throughout the hospital, and placing multiple tags on everything and everyone, might get around this dilemma, it’s not desirable, adds cost and is a nightmare to manage. Whether patients or staff will even tolerate wearing multiple tags, and whether equipment can accommodate multiple tags, is highly questionable.

What are my options?

Dual-mode systems integrate UWB with a signal-strength system. Both receiver types hear all of the tags and can receive location information from anywhere in the organization. UWB provides the accuracy of an interaction-grade RTLS where it’s needed, and the signal-strength system provides lower cost zone- and room-level accuracy. The choice of which to use is a matter of preference. Some users want to leverage their Wi-Fi network for location, and some want to install an overlay technology and keep Wi-Fi for data and voice.

An installation might include UWB for interaction-level accuracy only in the ED and a signal-strength system elsewhere, followed later by a surgical suite upgrade that includes UWB readers, with no need to replace any legacy systems. This flexibility makes dual-mode systems a low-risk option when trying to make an initial RTLS purchase. Perhaps more importantly, dual-mode systems offer RTLS at competitive price points, putting organizations on the first rung of the “high accuracy, high value” RTLS ladder, which can be scaled as needs require and budgets allow.

Nesconset Center Employs UWB RTLS: A mini case history

 

As the number of people needing skilled living assistance increases, facilities employ technology to improve care management for their residents.

Long Island-based Nesconset Center for Nursing and Rehabilitation in New York, recently implemented an Ultra-wideband (UWB) real-time location system (RTLS) to improve the accuracy of locating Alzheimer’s and Dementia patients, caregivers and various assets throughout the facility. The RTLS, from Time Domain Corp., Huntsville, Ala., includes tags, readers and antennas, and software from Sysgen Data Ltd., Melville, N.Y.

According to Robert Heppenheimer, Nesconset’s executive director and owner, “The ability of our staff to locate their patients and assets associated with the patients allows for better care management and faster response times for patient needs and requirements. For the first time, we can head off problems before they happen, which in turn, helps lower the risk of elopements.”

Nesconset reduces the risk of elopements using the integrated messaging system. Patients wear UWB tags, called “Smart Buddies.” The tags have “rules” that are programmed into the system’s software, associating them to the patients who are wearing them. When a Smart Buddy violates a rule assigned to it, the system alerts the proper staff members via a Windows Mobile 6 device that immediately communicates the violations to a certified nurse assistant (CNA). The CNA responds to the issue based on the urgency of the alert, which can be broadcast to staff via e-mail, text messages, cell phones, alarms and flashing lights.

The UWB system also automatically gathers information on the precise interactions between Nesconset staff and patients. This frees staff from manual data logging, improves data accuracy and optimizes compliance reporting. Precise tracking of equipment also improves utilization and automated billing.

Staff involvement in the program enables valuable information to be collected for future use in determining the best possible methodologies for treating patients afflicted with Alzheimer’s disease and Dementia.

Adrian Jennings is CTO at Time Domain Corp., Huntsville, Ala. Contact him at [email protected].

July 2008

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