ST. LUKE'S HEALTH CARE SYSTEM
Hospitals have been some of the earliest adopters of wireless local area
networks (WLANs). The clinician user population is typically mobile and
spread out across a number of buildings, with a need to enter and access
data in real time. St. Luke's Episcopal Health System in Houston, Texas
(www.stlukestexas.com) is a good example of a hospital that has made
effective use wireless technologies to streamline clinical work processes.
Their wireless network is distributed throughout several hospital buildings
and is used in many different applications. The majority of the St. Luke’s
staff uses wireless devices to access data in real-time, 24 hours a day.
Examples include the following:
• Diagnosing patients and charting their progress: Doctors and
nurses use wireless laptops and tablet PCs to track and chart patient
• Prescriptions: Medications are dispensed from a cart that is wheeled
from room to room. Clinician uses a wireless scanner to scan the
patient's ID bracelet. If a prescription order has been changed or
cancelled, the clinician will know immediately because the mobile device
displays current patient data.
• Critical care units: These areas use the WLAN because running hard
wires would mean moving ceiling panels. The dust and microbes that
such work stirs up would pose a threat to patients.
• Case management: The case managers in the Utilization Management
Department use the WLAN to document patient reviews, insurance
calls/authorization information, and denial information. The wireless
session enables real time access to information that ensures the correct
level of care for a patient and/or timely discharge.
• Blood management: Blood management is a complex process that
involves monitoring both patients and blood products during all stages of
a treatment process. To ensure that blood products and patients are
matched correctly, St. Luke’s uses a wireless bar code scanning process
that involves scanning both patient and blood product bar codes during
the infusion process. This enables clinicians to confirm patient and blood
product identification before proceeding with treatment.
• Nutrition and diet: Dietary service representatives collect patient
menus at each nursing unit and enter them as they go. This allows more
menus to be submitted before the cutoff time, giving more patients
more choice. The dietitian can also see current patient information, such
as supplement or tube feeding data, and view what the patient actually
received for a certain meal.
• Mobile x-ray and neurologic units: St. Luke’s has implemented the
wireless network infrastructure necessary to enable doctors and
clinicians to use mobile x-ray and neurologic scanning units. This makes
it possible to take x-rays or to perform neurological studies in patient
rooms. This minimizes the need to schedule patients for neurology or
radiology lab visits. The mobile units also enable equipment to be
brought to the bedside of patients that cannot be easily moved. The
wireless neurology and x-ray units have also helped to reduce the time
between diagnosis and the beginning patient care.
St. Luke's first WLAN was deployed in January 1998 and made the hospital
an early pioneer in wireless health care applications. St. Luke’s first wireless
LAN was implemented in a single building using access points (APs) made by
A principal goal of this initial installation was to improve efficiency.
However, sometimes the WLAN had the opposite effect. The main problem
was dropped connections. As a user moved about the building, there was a
tendency for the WLAN to drop the connection rather than performing the
desired handoff to another access point. As a result, a user had to
reestablish the connection, log into the application again, and reenter
whatever data might have been lost.
There were physical problems as well. The walls in part of the building
were constructed around chicken wire, which interfered with radio waves.
Some patients' rooms were located in pockets with weak radio signals. For
these rooms, a nurse or doctor would sometimes lose a connection and have
to step out into the hallway to reconnect. Microwave ovens in the
kitchenettes on each floor were also a source of interference.
Finally, as more users were added to the system, the Proxim APs, with a
capacity of 1.2 Mbps, became increasingly inadequate, causing ongoing
To overcome the problems with their original WLAN and reap the potential
benefits listed earlier in this case study, St. Luke's made two changes
[CONR03, NETM03]. First, the hospital phased out the Proxim APs and
replaced them with Cisco Aironet (www.cisco.com) APs. The Cisco APs, using
IEEE 802.11b, operated at 11 Mbps. Also, the Cisco APs used direct
sequence spread spectrum (DSSS), which is more reliable than the
frequency-hopping technique used in the Proxim APs.
The second measure taken by St Luke's was to acquire a software
solution from NetMotion Wireless (netmotionwireless.com) called Mobility.
The basic layout of the Mobility solution is shown in Figure C9.1. Mobility
software is installed in each wireless client device (typically a laptop,
handheld, or tablet PC) and in two NetMotion servers whose task is to
maintain connections. The two servers provide a backup capability in case
one server fails. The Mobility software maintains the state of an application
even if a wireless device moves out of range, experiences interference, or
switches to standby mode. When a user comes back into range or switches
into active mode, the user's application resumes where it left off.
In essence, Mobility works as follows: Upon connecting, each Mobility
client is assigned a virtual IP address by the Mobility server on the wired
network. The Mobility server manages network traffic on behalf of the client,
intercepting packets destined for the client's virtual address and forwarding
them to the client's current POP (point of presence) address. While the POP
address may change when the device moves to a different subnet, from one
coverage area to another, or even from one network to another, the virtual
address remains constant while any connections are active. Thus, the
Mobility server is a proxy device inserted between a client device and an
Enhancing WLAN Security
In 2007, St. Luke’s upgraded to Mobility XE mobile VPN solution [NETM07].
This migration was undertaken to enhance security and compliance with
HIPPA data transmission and privacy requirements. Mobility XE server
software was deployed in the IT department’s data center and client
software was installed on laptops, handheld devices, and tablet PCs.
With Mobility XE running on both clients and servers, all transmitted
data passed between them is encrypted using AES (Advanced Encryption
Standard) 128-bit encryption. Mobility XE also serves as an additional
firewall; devices that are not recognized by the Mobility XE server are not
allowed to access the network. This arrangement helped St. Luke’s achieve
its IT goal of having encryption for all wireless data communications.
Mobility XE also enables the IT department to centrally manage all
wireless devices used by clinicians. This allows them to monitor the
applications currently being used by any device or user, the amount of data
being transmitted, and even the remaining battery life of the wireless device.
If a Mobility XE device is stolen or lost, it can be immediately quarantined by
IT executives at St. Luke’s view wireless networking as key lever in their
quest to increase clinician productivity and improved patient care. Mobile
EKG units have been deployed bringing the total of wireless devices in use to
nearly a 1,000.
1. Visit the NetMotion Web site (www.netmotionwireless.com) and access
and read other Mobility XE success stories. Discuss the patterns that
can be observed in the benefits that Mobility XE users have realized via
its deployment and use.
2. Do some Internet research on the security implications of HIPPA
requirements for hospital networks. Discuss the major types of
security mechanisms that must be in place to ensure hospital
compliance with HIPPA requirements.
3. Do some Internet research on the use of VLANs in hospitals.
Summarize the benefits of using VLANs in hospitals and identify
examples of how St. Luke’s could further enhance its wireless network
by implementing VLANs.
[CONR03] Conery-Murray, A. “Hospital Cures Wireless LAN of Dropped
Connections.” Network Magazine, January 2003.
[NETM03] Netmotion Wireless, Inc. “NetMotion Mobility: Curing the
Wireless LAN at St. Luke’s Episcopal Hospital. Case Study, 2003.
[NETM07] Netmotion Wireless, Inc. “St. Luke’s Episcopal Health System: A
Case Study in Healthcare Productivity.” 2007. Retrieved online at:
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