An Open Source Framework for constructing
iPhone-based Remote Patient Monitoring
Grid Research Group
Agent Health, Inc.
Remote patient monitoring (RPM) is an important aspect of patient management and
support. RPM is becoming critical due to rising medical costs, the shortage of medical
personnel, and the increasing number of individuals with chronic diseases. MedRPM is a
software and hardware framework that allows medical vendors to quickly construct
commercial RPM solutions based on the Apple iPhone. The system is unique in that it
can support the triad of patient monitoring: health, safety, and environment. The iPhone
acts as the central patient management system collecting patient and environmental
monitoring data. An iPhone application called iRPM allows the iPhone to receive
wireless monitoring data from a number of sources and for patients to interact with the
iPhone to provide clinically relevant information. MedRPM is intended to spur the
adoption of RPM solutions in the medical industry. All software in the framework is open
Remote Patient Monitoring
Remote Patient Monitoring (RPM) refers to the monitoring and management of patient
health conditions. The monitoring occurs within a remote environment (remote from the
care provider) such as the patient’s home. Devices such as weight scales, glucometers,
pH sensors, temperature sensors, and blood pressure monitors transmit patient
monitoring data to a collection station within the patient’s environment. The data is then
transmitted to care providers who analyze the data to determine new treatment
regimens, modify existing regimens, treat declining health conditions, or diagnose
patient status. Home health solutions have been the early adopters of RPM solutions.
However, RPM solutions will see their greater need in the area of chronic care and
disease detection. Within this paper, we also include medical studies within the RPM
umbrella. A medical study is the remote monitoring of a patient for a pre-determined
amount of time (for example, twenty-four hours) to determine the presence or absence
of a medical condition.
A typical RPM architecture is shown in Figure 1: Example RPM Architecture. The
patient’s home contains a computer server that receives data transmitted from
monitoring devices in the home and/or worn by the patient. The devices contain a
wireless transmitter which sends patient condition information using any number of
industry communication protocols such as Bluetooth or Zigbee. The server receives the
The MedRPM System 2
data, stores it, and later transmits the data to another server based at the care provider’s
location. Patient monitoring data is typically analyzed at the care provider’s location
although minimal analysis may also be done within the patient’s environment. The
patient’s cellular phone is used for communication with the care provider using cellular,
instant messaging, and email. Monitoring is provided only at the patient’s environment.
Once a patient leaves the environment, support is suspended. There are now RPM
solutions (including MedRPM) which do support patient monitoring outside the patient’s
Figure 1: Example RPM Architecture
The MedRPM framework is unique. It uses the Apple iPhone as the primary “server”
both within and outside the patient’s environment. The iPhone becomes the central
device that supports data collection, data processing, minimal data analysis, and patient-
physician communication. Figure 2: MedRPM Architecture shows the general
architecture of the MedRPM framework.
Figure 2: MedRPM Architecture
With the iPhone as the central server, the framework is very quick to deploy. Patients
download the vendor iRPM application from the Apple App Store onto their iPhone and
they are ready for monitoring. The architecture allows patients to enter other medical
environments which have been enhanced for monitoring and immediately participant in
those environments. In the future, all hospitals will be enhanced for wireless patient
monitoring and a patient, by merely entering the hospital, will be recognized, monitored,
and even superficially treated before seeing any care provider. The iPhone represents
the first consumer cellular solution that supports enough computing power to be truly
viewed as a server.
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MedRPM is intended to spur the adoption of RPM solutions in the medical industry.
MedRPM has two goals: first, enable medical vendors to quickly construct RPM
solutions with minimal cost. Reducing the cost of constructing RPM solutions (and
hence the consumer cost of the resulting solution) is paramount to RPM adoption;
second, enable the inclusion of advanced core features for RPM solutions. By providing
core features in MedRPM, medical vendors can concentrate their expertise on providing
focused disease management solutions.
RPM solutions consist of both hardware and software components. The software
components can be provided free of cost through open source initiatives. The hardware
components are much different because they are provided by medical vendors.
MedRPM is attempting to provide a number of free smart motes that can be used
immediately by the patient. The patient will distribute the smart motes in their
environment per care provider instructions. The smart motes will immediately form a
network and communicate with the iRPM iPhone application. Other devices used to
monitor the patient must be purchased separately by the care provider or the patient.
There are a number of issues with RPM that are slowing full adoption including:
Cost. The cost of specialized RPM equipment is expensive such as enhanced
weight scales that support wireless communication.
Intrusive. Reviewing captured patient monitoring data requires the time of a care
provider. Time which is in greater demand in today’s medical environment. The
required time does not fit well within the hectic office workflow of a care provider.
Reimbursement. Healthcare payers are reluctant to reimburse costs related to
RPM without clear evidence of the patient benefits.
Lack of Supporting Software. Lack of effective patient management software to
process patient monitoring data.
The MedRPM framework takes advantage of the current trends in software computing
which will drive the effectiveness of RPM solutions and hopefully address the above
issues. With the current trends of open source software, new analytical and supporting
software for RPM solutions will be free. This will remove a large part of the cost burden
to care providers. In addition, smart phone technology has now reached a point in which
they can replace existing dedicated RPM patient devices. Smart phones can now
support complex software, support numerous networking capabilities including Bluetooth
and Wi-Fi, have onboard sensors, cameras, and audio recording capabilities. Smart
phone features are being added at a mesmerizing pace much faster than medical
vendors using specialized patient devices.
In the sensor market, smart motes are a new technology that is rapidly reaching
maturity. Smart motes are small computers (typically one inch square) that have
sensors. Smart motes can be sprinkled throughout a patient environment and provide
visibility into the environment including temperature, appliance usage, and security.
Smart motes are also replacing simple wireless transmitters found in today’s medical
devices to enable the devices to take on more tasks. Sensors are advancing at a rapid
pace. There are now sensors which can measure vital signs and specific symptoms in a
patient. These sensors are getting smaller, smarter, cheaper, and less intrusive.
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The MedRPM Framework
MedRPM consists of four major components: the Apple iPhone docking shell, the iPhone
application called iRPM, the web application server called MedView, and a collection of
smart motes. Aside from the smart motes that monitor environmental data, the MedRPM
framework does not include wireless monitoring devices. Patients and care providers
must purchase the necessary monitoring devices related to their disease and support
requirements. MedRPM provides a list of devices that currently work with the framework.
It is expected that medical vendors using the MedRPM framework to create commercial
RPM solutions will expand on that list. Figure 3: The MedRPM Framework shows the
components of the MedRPM system.
Figure 3: The MedRPM Framework
The iPhone docking shell contains sensors, an additional battery, and a smart mote. The
embedded smart mote allows the iPhone to converse with Zigbee-based wireless
medical monitoring devices. Zigbee is an industry standard communication protocol that
provides a number of advanced features for small wireless devices. We expect Zigbee to
become the dominate protocol in the medical industry for wireless devices. The
WebRPM framework does support other communication protocols such as Bluetooth.
The iPhone slides into the docking shell which connects to the iPhone 30 pin connector.
It should be noted that Apple is very restrictive in the use of the 30 pin connector and
Bluetooth. A vendor must be part of the Apple “Made for iPod” program in order to create
devices that use the 30 pin connector and Bluetooth.
The MedRPM framework provides the following core features:
Alert System. Both the iRPM application and the MedView application server
contain early detection and intervention features. WebRPM can alert care
providers and patients as to issues that require immediate attention. For
example, if a patient’s heart rate exceeds a defined threshold then an alert would
be generated and sent to the care provider and the patient.
Data Integration. Data integration is the ability of MedRPM to exchange data
with existing medical data systems. Data integration is an important aspect of
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patient support which may involve multiple care providers. The MedView
application server can send and receive patient information in any number of
industry data formats such as HL7, Microsoft Excel spreadsheets, and XML.
MedView can send and receive the information in any number of network
protocols such as web service calls, SOAP, HTTP, FTP, and email.
Timers. The iRPM iPhone application supports multiple timers to schedule major
patient regimen tasks such as when to take medication, when to create a diary
entry, and when to create a data entry. These timers are necessary to ensure the
patient follows specific regimens created by their care provider. iRPM will notify
the care provider if a specific scheduled task is not accomplished by the patient.
Data capture. MedRPM supports data capture from a myriad of medical devices
including anticipated next generation devices. Data capture is the most
important aspect of any RPM solution.
Patient education. Both the iRPM application and the MedView application
server can provide focused patient information for disease management,
nutrition, and exercise recommendations. Patient information is the cornerstone
of any medical regimen.
Social interaction. The MedView application server supports a patient blog to
allow patients to interact to share advice, experiences, and thoughts.
Patient Safety. The MedRPM framework includes a collection of smart motes for
monitoring patient safety in their environment. Smart motes are used to monitor
environmental temperature, appliance usage, and security such as monitoring
doors and windows. The iPhone sensors are used to detect patient falls while
the GPS unit is used to track the location of patients. Patient location monitoring
is important for patients with forms of dementia.
Physician-Patient Communication. A care provider can communicate directly
with their patient in the form of “notes” or messages using the Apple Push
Notification system. The patient’s iPhone will vibrate and an indicator will
appear on the phone to tell the patient that a message has been received from
their care provider. Communication is also supported using the standard
iPhone capabilities such as email, text messaging, and cellular.
Remote Data Analysis. An embedded rule system in the iRPM application will
interpret patient monitoring data as it arrives to the iPhone. The rule system will
alert the care provider via email immediately if the data exceeds normal
thresholds or any other criteria defined by the care provider. New threshold or
analysis rules can be uploaded to the patient’s iPhone in real-time.
Simulation Mode. The iRPM application can execute in a special “simulation
mode” in which the application will “play” a previous session to allow patients
and physicians to participate in “Human Computer Interaction” (HCI) studies.
These studies do not require medical monitoring devices freeing the
participants to concentrate on HCI issues.
Data Visualization. Ability to graphically display patient monitoring data both
on the iPhone and the MedView application server.
Real-time Update. Ability to upload to the patient’s iPhone in real-time new
information such as analysis rules, patient background information, session
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details, event types, data types, and patient education material. This can be
done without patient participation.
HCI Features. Advanced “Human Computer Interaction” (HCI) features to allow
patients to communicate with the iPhone with minimal effort. For example,
patients can double-tab the iPhone screen and the iPhone begins recording a
ten second audio memo without the patient having to view the iPhone.
Data capture is the primary task of any RPM system. The care provider needs quality
monitoring data to ensure they have a good understanding of the patient’s status.
Without good data, proper patient support is impossible. Data may come from a number
of sources. Figure 4: Patient Data shows the possible sources of clinical data for
Figure 4: Patient Data
In addition to patient monitoring data from wireless medical devices, the iRPM
application provides a screen for patients to manually input data including temperature,
heart rate, blood pressure, and weight. For example, a timer in the iRPM application
would notify the patient that it is time to take vital signs. The patient would then enter the
vital sign data values manually into iRPM. The physician can add or remove data types
such as “heart rate” from the iPhone to fit the RPM solution. Patients can enter
reactions, events, and symptoms through a diary component. Finally, patients can create
audio memos for the care provider. Support for manual patient monitoring data entry is
important for situations where wireless enabled medical devices are too expensive or
unavailable. Studies have shown that manual data entry is not as intrusive as one would
suspect. Patients welcome the fact that someone is watching out for their safety and
data entry is a reminder of that fact.
Care providers can send patient monitoring data directly to the iPhone either locally
through Wi-Fi or remotely through the Apple Push Notification system. Patient visits to
their non-primary care providers may generate data which needs to be added to their
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iPhone. Chronic care patients typically have more than one care provider. Not all the
care providers are enabled for patient monitoring. Having access to the patient’s iPhone
allows all involved care providers to directly contribute to patient support.
The MedRPM system is designed to support the use of wireless medical sensors. Many
embedded sensors in the industry support wireless communication protocols such as
Bluetooth and Zigbee. These sensors may talk directly to the iPhone or indirectly
through other devices (for example, smart motes). The iRPM application will evolve to
support an ever increasing myriad of devices. New updates to the iRPM application will
be made available through the Apple App store. The new updates will not affect
monitoring data currently stored on the patient’s iPhone so the updates can be applied
even during active patient monitoring sessions. Many consumer health devices have
embedded wireless transmitters. The data can be transmitted directly to the iPhone for
storage and processing. An example consumer health device is a weight scale. An ever
increasing number of medical devices such as heart monitors and blood pressure
monitors now have wireless capabilities. The data can be transmitted directly to the
iPhone for storage and processing. Finally, smart motes (very small computing systems)
distributed within the patient’s environment can communicate directly with the iPhone
through the smart mote embedded in the docking shell.
The iPhone is unique from other cellular devices in that it contains onboard sensors. The
sensors provide an opportunity to use the iPhone to automatically generate patient
monitoring data in support of RPM. For example, the iPhone accelerometer can be used
to determine if the patient has fallen or is in a supine position. Research is needed to
determine the effectiveness of the accelerometer for RPM but it does provide some
interesting possibilities. The iPhone proximity sensor is used for Human-Computer
Interaction (HCI) purposes. Swiping the proximity sensor can automatically generate
specific diary events or specific patient monitoring data. It is envisioned that the docking
shell will contain additional sensors such as a heart rate sensor. A patient will be able to
press their thumb onto the docking shell and the shell will automatically generate heart
Location information via the iPhone GPS capabilities is paramount in the support of
patient conditions such as dementia. The iRPM application can track the patient to
ensure they remain within their environment geographical boundaries. iRPM can
generate “out of boundary” patient events while at the same time notifying the patient’s
care provider. Care providers can track patients once they leave their environment.
Diary events can be created automatically if patients are tracked within the geographic
boundaries of known restaurants. Location tracking can be intrusive however for critical
care patients its support is paramount.
Although this paper presents a superficial discussion on the subject, smart motes are
destined to become a major enabling technology for the medical industry. Smart motes
are sometimes referred to as sensor networks. Smart mote networks are collections of
distributed wireless devices that observe and respond to events within an environment.
Smart motes have evolved from simple sensors to full fledge computer systems able to
execute software solutions. A smart mote typically consists of five components on a
small (1 inch square) platform: a microprocessor, memory, a transceiver (transmitter and
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receiver), sensors, and a battery. Smart motes will initially be used to monitor patient
environmental conditions such as temperature. Next generation solutions will have smart
motes embedded in all wireless medical devices where they will carry on complex tasks
and participate in patient monitoring networks.
Patient Data Format
Data traveling between MedRPM components can exist in a number of formats from
proprietary to medical standards like HL7. MedRPM defines its own data format for data
that travels between the iPhone and the MedView web application server. The following
is an example WebRPM XML data value sent from iRPM to MedView.
<RelatedID>Mount Sinai Diet Study</RelatedID>
The iRPM iPhone application is designed to understand a number of data formats. Over
time, the iRPM application will support additional data formats driven mostly by the
available sensors in the market. Figure 5: Data Formats in MedRPM shows the
protocols supported among components in the MedRPM framework. Realize that data
traveling through the network consists of not just patient monitoring data. iRPM also
accepts data concerning patients, analysis rules, patient events, and sessions. The
intent is not to have the WebRPM framework impose any data format constraints on
vendors using WebRPM to create commercial solutions.
Figure 5: Data Formats in MedRPM
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In Figure 5: Data Formats in MedRPM, notice that the communication is bi-directional for
smart motes. Smart motes are able to form networks with other smart motes including
the one embedded in the WebRPM iPhone docking shell. This is very important since a
smart mote is much like a small computer which can run software and store data.
Future enhancements to the WebRPM framework will support the updating of smart
mote software in real-time. iRPM will be able to send data and software directly to a
specific smart mote. Smart motes will be able to run data analysis software alleviating
some of the work of the iRPM iPhone application and reducing the amount of wireless
The iRPM iPhone Application
iRPM is an iPhone native application designed to support RPM solutions. The patient is
able to interact with the iPhone via the iRPM application to input clinically relevant
information such as meals, symptoms, and monitoring data. The iRPM application can
exchange patient data with the MedView application server.
The main screen for the iRPM application is the patient dashboard. The dashboard
provides important information about the patient including the number of active alerts,
last received patient monitoring data value, the current active session, the number of
unread patient memos, and a care provider emergency contact button. The emergency
button allows the patient to quickly contact their care provider with minimal effort.
A session is a fundamental concept in the iRPM application. A session is a means of
organizing patient monitoring data. All monitoring data stored in the iPhone is stored
within the context of a session. WebRPM makes no requirements as to when to create
sessions or how many. A typical session would include data for a specific study or data
defined for reimbursement under the patient’s healthcare plan. Sessions can be created
on the iPhone through the iRPM application or sessions can be uploaded onto the
iPhone by the care provider using the WebView application server. A session may be
"active" which means it is currently the session of focus. Or "not active" which means
either it is an older session or the session is being defined. iRPM can manage and store
any number of sessions but only one session may be active at any one time. When a
session is active, it will be displayed on the patient dashboard and all created memos,
diaries, and patient monitoring data will be related to the active session.
A patient participates in a session under the supervision of a care provider. As part of
the setup process for a session, the care provider must define the patient(s) within
iRPM. iRPM can store any number of patients. To indicate that the patient participates in
a particular session, the physician must link the two (session and patient) via the
Session Detail screen in iRPM. The general attributes of a patient include the patient’s
first and last name, the patient identifier (if applicable), gender, height, weight, and an
iPhone device token value. An iPhone device token value is used when pushing data
from the WebView application server to the patient's iPhone.
A great feature of the iRPM application is the ability for patients to create audio memos
for the care provider. Audio memos provide an effective means of communication
between a patient and their care providers. There are no restrictions as to the size or
length of an audio memo except for the physical data limits of the patient’s iPhone.
Patients may create as many memos as needed for the session.
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Care providers define medical rules that run on the iPhone. These rules attempt to
analyze patient monitoring data as it arrives to the iPhone. An example threshold rule
would be "if the pH value is below 2.0 then alert the patient to change their current
behavior". Patient experiences from previous sessions are incorporated into new
medical rules thus creating sophisticated RPM solutions. Rules may create alerts to the
patient which either informs or instructs the patient. The Alert feature may be turned off
using the iPhone Settings application. A value appears on the iRPM dashboard
indicating the number of alerts that have occurred while the session was active. An Alert
detail page will provide further details to the patient. An example instruction would be for
the patient to create a new diary event. Doing so will allow the physician to understand
why the alert occurred. Some alerts will also automatically notify the physician using
email or instant messaging.
Physicians can send digital notes to patients using the Apple Push Notification system.
This is much like instant messaging but the notes are delivered directly to the iRPM
application and do not use the user's SMS facility. The Physician Notes feature may be
turned off using the iPhone Settings application. A value appears on the patient
dashboard indicating the number of notes that have occurred while the session was
active. A Physician Note detail page will provide further instructions to the patient if
required. An example instruction would be to ask a patient to immediately contact their
The capturing of patient monitoring data from medical devices is an important aspect of
RPM. But just as important is the numerous events that occur during a session. Example
patient events include coughing spells, heartburn occurrences, and wheezing. iRPM
supports a patient diary where patients can add events during a session. Analysis
software can later correlate the patient’s data to events. The iRPM application attempts
to add diary events automatically when they can be deduced through the iPhone
sensors or the WebRPM docking shell sensors. An event consists of an event type and
duration. WebRPM defines a number of event types such as "Cough", Heartburn", and
"Meal". iRPM allows physicians to define any number of additional event types per
session. Or they may choose to remove any number of the pre-defined event types for a
particular session. Those enhanced event types will show up on the Diary detail page.
The event types are managed using an Event Type Detail screen.
WebRPM will continually add features to the iRPM application to advance the way
patients interact with the application. This is related to a branch of research known as
"Human Computer Interaction" or HCI. This is the study of how humans interact with a
computer (or application in this situation). The iPhone provides a number of novel
features which allows different ways for people to interact with applications. For
example, the ability of the iPhone to vibrate, to create audio sounds, the accelerometer,
push notification, and the proximity sensor. WebRPM has added a number of features to
support advance HCI including the Alert facility and the Physician Note facility. All HCI
related features can be enabled or disabled using the iPhone Settings applications.
Patients are expected to predominately use the audio memos features on pHWear as a
way to communicate information to the physician during a session. Manually creating an
audio memo can be difficult at times when the patient is focusing on another task or
when it is dark and difficult to focus on the iPhone. The Auto Memo feature solves these
problems by allowing the patient to record a memo merely by tapping twice anywhere on
the patient dashboard screen of the iRPM application. When the screen is double
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tapped, the Audio Memo screen appears and the patient is asked to record their memo.
The recording will last for 10 seconds at which time iRPM will automatically stop the
recording and return to the patient dashboard screen. This requires no additional work
on behalf of the patient except for the initial double tap.
Additional HCI features will be added as experience is gained with the iRPM application.
The iRPM application provides a screen to manually input many types of patient
monitoring data including temperature, heart rate, blood pressure, and weight. The care
provider can add or remove “data types” from the iPhone to fit the RPM solution. This
can be done in real-time.
The WebView Application Server
The WebView application server is the main interaction point for care providers. Care
providers use WebView to manage and support their patients. WebView has two major
Main collection point for patient monitoring data.
Patient monitoring data analysis.
To enable communication from the patient’s iPhone to WebView, a patient’s iPhone is
configured to indicate the location (Web URL) of the corresponding WebView application
server. That server becomes the collection point for the monitored patient. When
requested, the iRPM application will send patient monitoring data to the WebView
server. To enable communication from WebView to the patient’s iPhone, WebView
stores the device token for the patient’s iPhone. WebView uses the Apple Push
Notification Service (APNS) to communicate with patient iPhones. Payloads for APNS
are intended to be small. WebView messages are limited to alerts, physician memos,
and “data available” alerts. “Data Available” alerts tell the patient’s iPhone that data is
available on the WebView application server and that it should begin uploading the data.
This relieves the iRPM application from having to poll the WebView application server
periodically for data availability.
WebView is also used by patients although the main interaction point for patients is the
iRPM application. Patient features in MedView include education, socializing with other
patients through the patient blog, and communicating with their care provider.
WebView is a web-based application which can be installed on a hosted server (cloud),
a local server, or even a laptop computer. WebView is accessed using standard web
browsers. Figure 6: WebView Application Server shows a few of the many features
supported by WebView.
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Figure 6: WebView Application Server
WebView receives patient monitoring data from the iRPM iPhone application and stores
the data for analysis. WebView can request data from a specific iRPM application which
instructs the application to start the download process. If the patient’s iPhone is on the
same network as the WebView application servicer, WebView can download the data
directly without having to instruct the application.
WebView contains a robust rule engine and rule database defined by experts in the
medical field. These rules can be applied to patient monitoring data to determine any
issues that require attention.
Chronic care patients typically have more than one care provider. These providers need
to share information. The WebView application server can send filtered patient
monitoring data to any location using a number of network protocols including web
services, SOAP, HTTP, FTP, and email. In addition, WebView can convert patient
monitoring data to any number of data formats including XML, Microsoft Excel
spreadsheets, and HL7.
WebView contains an event-correlation engine. This implies that with proper setup, the
engine can take patient events and derive the possible reasons why the events
occurred. Care providers can take the information and complete the diagnosis with
minimal effort. The event correlation engine is intended to help alleviate the demands of
RPM on care providers. This will speed the adoption of RPM in the medical community.
After an analysis of patient monitoring data, the care provider must derive patient
regimens. The regimens are in the form of medical workflows that have been predefined
by the medical community and the care provider. WebView provides a graphical medical
workflow designer. The medical workflows may cause new information to be sent to the
patient’s iPhone such as new analysis rules, patient educational information, and new
timer values for scheduling medications.
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MedRPM is one of the first open source RPM frameworks that we have seen in the
medical industry. The MedRPM novel approach to constructing RPM solutions will
hopefully speed the adoption of RPM solutions. Creating MedRPM as an open source
solution will allow medical software developers around the U.S. to contribute to the
success of MedRPM. This should accelerate the quality and capabilities of MedRPM
much faster than would be the case if MedRPM was a vendor proprietary solution. The
experiences in evolving MedRPM will contribute greatly to other sensor-based solutions
in the medical industry such as hospital sensor networks.
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