23-05-2014, 04:09 PM
Monitoring Patients’ Signs Wirelessly
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Abstract
Recent developments in off-the-shelf wireless
embedded computing boards and the increasing need for
efficient health monitoring systems, fueled by the
increasing number of patients, has prompted R&D
professionals to explore better health monitoring systems
that are both mobile and cheap. This work investigates
the feasibility of using the ZigBee embedded technology
in health-related monitoring applications. Selected vital
signs of patients are acquired using sensor nodes and
readings are transmitted wirelessly using devices that
utilize the ZigBee communications protocols. A prototype
system has been developed and tested with encouraging
results.
INTRODUCTION
The increasing cost of in-bed hospitalization and
the recent technological advances in low-power
integrated circuit sensors coupled with the introduction
of power efficient protocols such as Bluetooth and
ZigBee has tempted researchers to study the
establishment and usage of wireless networks as a
vehicle for transmitting patients’-related information
without the need to confine them to a premise [1, 2].
Wireless-based non-confining monitoring systems
improve the quality of life for the patients while
serving as a cost effective solution to the problem of
health care monitoring that is worsening with the
increase in the aging population. The rapid
development in the telecommunication field and
mobile technology has accelerated the introduction of
telemedicine as a viable and reliable alternative.
Recent work [3, 4] includes using Bluetooth
technology coupled with the GSM technology to report
signs to PDAs held by the patient or his doctor.
Monitoring based on ultra wideband-based personal
area networks was reported in [5].
SYSTEM HARDWARE DESCRIPTION
The system is designed and built using the ZigBee
modules (Nodes) from Jennic Corporation [11]. Vital
signs’ sensors attached to the patient’s body are
interfaced to these Nodes (hereafter P-Node). The
complete P-Node is packaged in a light form and
carried by the patient. Sensed data is transmitted to a
ZigBee coordinator (Z-Coor) with a wide LCD display
that is carried by the supervisor nurse on the hospital
floor.
SYSTEM SOFTWARE DEVELOPMENT AND TESTING
The P-Nodes (units carried by the patients) together
with M-Nodes (units carried by the nurse) and Z-Coor
work in a star topology formation. Using this topology,
every device in the network can communicate only
with Z-Coor.
All units are programmed using C. Appropriate
code was developed to carry out various functions such
as configuring and enabling the A/D converters,
reading of data via specific ports or channels,
programming the timers, calculating the acceleration,
acquiring sensed data and formatting of payloads for
transmission, etc.
Each P-Node carried by a patient has a unique ID
(Node ID). A frame that includes this nodeID, Room
Temperature, Heart Rate, Body Temperature, and
computed Acceleration is created and sent to the Z-
Coor. Table 1 shows the frame format and content. The
“OK” indicator corresponding to the accelerometer
field indicates that the patient’s orientation is normal.
CONCLUSIONS
The paper discusses the implementation of a
monitoring system targeting patients on a hospital
floor. The system consists of end units carried by
patients that collect sensed data (health sign readings)
and transmit it to a coordinator unit at the hands of the
floor nurse. This is implemented using a ZigBee-based
network. Such wireless environments provide patients
with the ability to move around and feel confident