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Introduction
Many hospitals have begun the difficult task of developing a wireless network. The ICU at Memorial Sloan- Kettering Cancer Center (MSKCC) in
New York City, NY, has been a leader in the use of this new technology, and Neil A. Halpern, MD, FCCP, Chief of Critical Care Medicine and Director of the ICU at MSKCC, moderated a symposium discussing how a wireless network can be developed to improve efficiency and safety within a hospital. “In Memorial,
as in many other hospitals, we have been faced with a series of challenges at the bedside and institutionally,” stated Dr. Halpern, adding, “these include an increasing number of networked and stand-alone bedside medical devices, and the installation of multiple parallel wired and wireless networks that do not communicate with each other or transmit their information to the electronic medical record.” In addition, nurses are besieged with a myriad of alarms that conflict with one another. Therefore, MSKCC began implementing a hospital-wide wireless network to alleviate some of these problems. To this end, the
hospital established a “wireless laboratory” to study the effects of introducing wireless medical devices. To help caregivers understand the multitude of
challenges facing the hospital when developing a wireless network, Dr. Halpern introduced Pat Carragee, Director of Information Systems at MSKCC, to discuss the basics of wireless networks and some of the challenges faced by hospitals in implementing them.
Wireless Networking: Definitions and Challenges of Hospital-Wide Implementation
In the traditional hard-wired ICU, all rooms are fitted with data jacks, and each device is connected by cable to the jack and subsequently to the network(Figure 1A). Unfortunately, the addition of new bedside medical devices requires the installation of more data jacks and more cable in the walls and ceilings. Equally important is that device mobility is limited to the length of the cable. With wireless connectivity, each medical device is connected to the network remotely, via a wireless transmitter. No additional cabling is required, and the plethora of cables lining the walls/ceilings can be replaced by antennas that capture the data from the medical devices “wirelessly” and relay it to caregivers (Figure 1B). Another improvement is that the device can be located anywhere within the wireless coverage zone and still remain on the network. In addition, the accelerating use of PDAs, cell phones, laptops, and pagers by caregivers makes it necessary for hospitals to begin changing their current hard-wired systems to a wireless network.
By allowing doctors and nurses unlimited access to the patient’s monitors, via a wireless network, the patient can receive faster and more efficient care.
All of these advantages to a hospital implementing a wireless network, however, do require that caregivers be knowledgeable of some of the terminology,
as well as some of the difficulties in developing a wireless network.
Wireless Fidelity Antennas
“Wireless Fidelity (Wi-Fi) is the standard for Ethernet traffic, or, basically, cable traffic over radio frequencies that the government has designated as free-radio frequencies,” said Mr. Carragee, adding that most traffic would use the 802.11b Wi-Fi standard (2.4 GHz 11 Mbps), but that 802.11 g (2.4 GHz 54 Mbps)and 802.11 a (5.0 GHz; 54 Mbps) standards are also used. Mr. Carragee stated, “The antennas and network adaptor cards that are now being deployed tend
to work in 802.11 b and g,” adding, “802.11 a may be used more often in the future. Combo antennas that support all three Wi-Fi standards would then be installed.” Wireless access points can cover 150- to 200-foot area in the hospital. To ensure continuity of the transmitted signals, each floor at MSKCC has six antennas (Figure 1B). The antennas terminate in special communications closets filled with wireless switches. These closets also contain the many wires that represent the proximal ends of the standard wired jacks that are located at each bedside. Although the wireless network in the hospital is focused on medical devices, the reality of our communicative world requires that each antenna has two additional functions: patient internet access and cell phone use. Therefore, antennas at MSKCC also provide patients’ family and friends access to the Internet, as well as telephony services. These three wireless services can be overlaid on the same antenna, but they do require different security measures.
Specific Challenges
There is a plethora of challenges in developing and maintaining a wireless network in a hospital. Some of the challenges discussed by Mr. Carragee
included:
Troubleshooting (Surveying)
Prior to installing the wireless network, a site survey that assesses the area to be “wired for wireless” must be performed. Once the wireless network is installed, Mr. Carragee stressed that it is very important to constantly perform additional surveys to ensure that the wireless signals continue to be strong. “Every time a facility is renovated, every time there is any kind of equipment that is brought into it, or if you are opening up a new floor, you have to redo the survey,” said Mr. Carragee, adding, “you walk around with a Geiger Counter-type device to see exactly the signal strength.” Interference is also a constant parameter that needs to be monitored. “Hospitals are often in urban areas and ‘hot spots’ outside the hospital may interfere with the hospital’s network.”
Data Size
There is a finite amount of information that can go through an access point. Knowledge of the size of data being transmitted (e.g., large picture files vs
small text messages) needs to be understood and appropriate measures employed to ensure all data are quickly transferred. “As you add dense applications
for monitoring, you have to continually track the capacity of any given wireless access point to handle the wireless load,” said Mr. Carragee.
Troubleshooting (Performance)
Mr. Carragee discussed the challenges of assuring the integrity of the wireless network. With all the wired or wireless devices/monitors connected to the network, it is important that the caregiver be aware when any aspect of the system is not functioning properly. Mr. Carragee credited the Cardiopulmonary Corporation for developing a technique to assess this problem. “If a medical device is registered as online on the network, the system informs the caregiver if the device dropped off the network, just as it would tell a caregiver if there is a patient alarm,” said Mr. Carragee.
Next: Wireless in the ICU Continued
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