sip-based medical event monitoring system knarig arabshian and henning schulzrinne department of...
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SIP-based Medical Event SIP-based Medical Event Monitoring SystemMonitoring System
Knarig Arabshian and Henning Schulzrinne
Department of Computer ScienceColumbia University
{hgs,knarig}@cs.columbia.eduJune 6, 2003
OverviewOverview
Basics of SIP (Session Initiation Protocol)
Details of SIP event notification architecture
Medical Logic Modules and SIP XML Messages and SIP Benefits Conclusions
SIP-based Medical Event SIP-based Medical Event Monitoring SystemMonitoring System
Medical industry transitioning to Internet-based communication
SIP can work on a variety of devices Adopted as protocol of choice for third
generation wireless networks Used for Internet conferencing, telephony,
presence, event notification and instant messaging
What is SIP?What is SIP? The Session Initiation Protocol (SIP) is a signaling protocol
used for establishing sessions in an IP network. SIP is part of the IETF standards and is modeled upon other
Internet protocols such as SMTP (Simple Mail Transfer Protocol for e-mail) and HTTP (Hypertext Transfer Protocol for www)
SIP is also being used in Microsoft Messenger in Windows XP
A session could be a simple two-way telephone call or it could be a collaborative multi-media conference session.
Different services are possible Internet telephony Instant Messaging with buddy lists Event notification Device control
What is SIP?What is SIP? Two Components within SIP: User Agent and
the SIP Network Server. User Agent is the end system component
for the call The User agent can be both a User Agent
Client (UAC) and a User Agent Server (UAS) The client element initiates the calls and
the server element answers the calls. SIP Server is the network device that
handles the signaling associated with multiple calls.
What is SIP?What is SIP? Main function of the SIP servers is to provide
name resolution and user location Caller is unlikely to know the IP address or
host name of the called party Caller will dial an email-like address or a
telephone number associated with the called party.
A SIP proxy server receives requests, determines where to send these, and passes them onto the next server (using next hop routing principals).
home.com
office.com alice
bobm2.home.com
Basic call setupBasic call setup E-mail like identifier: <sip:[email protected]> Alice’s phone registers with home.com Bob dials [email protected]; Phone does DNS
Registrar
REGISTER home.com SIP/2.0To: sip:[email protected]: sip:[email protected]…
DNS lookup sip.udp.home.com
Resolve to m2.home.com
home.com
office.com
alice
bobm2.home.com
Basic call setupBasic call setup
Phone sends INVITE; acts as User Agent Client Server can proxy the call to current location
INVITE sip:[email protected] …To: sip:[email protected]: “Bob” <sip:[email protected]>…c=IN IP4 128.59.19.60m=audio 8000 RTP/AVP 0 5 8
User agent client
INVITE sip:[email protected] …
To: sip:[email protected]: “Bob”
<sip:[email protected]>…
Proxy
home.com
office.com alice
bobm2.home.com
Basic call setupBasic call setup Alice’s phone rings; acts as a User Agent Server When Alice picks up, call is accepted and bob’s
phone sends ACK to complete the setup
pc4.home.com
SIP/2.0 180 Ringing
ProxyUser agent
server
SIP/2.0 200 OK…c=IN IP4 135.180.144.32m=audio 9000 RTP/AVP 0 8
home.com
office.comalice
bob
Basic call setupBasic call setup Encoded audio packets sent over RTP
home.com
office.comalice
bob
Basic call setupBasic call setup When either party hangs up BYE is sent
BYE sip:[email protected]
Columbia SIP user agent Columbia SIP user agent (sipc)(sipc) Media
Audio, video, text, white board Screen sharing Shared web browsing
Advanced Presence, instant messaging Conference control Emergency notification and handling Device control
Subscribe/NotifySubscribe/Notify SIP has also been extended to generate
event notifications and instant messages
Users subscribe to an event with the SUBSCRIBE method and receive notifications via NOTIFY
This feature can be used for creating medical event monitoring systems
Subscribe RequestSubscribe Request Resembles that of a SIP INVITE Must have one “Event” header in the
header field which will specify the type of event it is subscribing to
Must also contain an “Expires” header which defines the duration of the subscription
Subscriptions to multiple events requires multiple subscribe messages to be sent to the notifier
To unsubscribe, it sends a SUBSCRIBE message with the ”Expires” field set to zero
Subscribe RequestSubscribe Request Can contain optional message body in
SUBSCRIBE request Further details of notification
methods of alerting (alarm, IM Messages, telephone calls)
Filtering of sub-events Standardized grammar to automate
the processing of the SUBSCRIBE request in the Notification Server
If message body is not present then Subscriber will expect the default method of alert
Notify RequestNotify Request The “Event” header will indicate the type of
emergency notification it is The message body of the NOTIFY message
will include specific instructions on the alert methods.
Notification server receives the subscription, adds the subscriber to the particular event list and then generates NOTIFY requests accordingly
CLIENT(SUBSCRIBER)
SUBSCRIBE sip:[email protected] SIP/2.0Event: heartmonitorExpires: 86400 From: sip:[email protected]: sip:[email protected]
SERVER(NOTIFIER)SIP/2.0 202 Accepted
From: sip:[email protected]: 86400
NOTIFY sip:[email protected] SIP/2.0Event: heartmonitorTo: sip:[email protected]: sip:[email protected]
Medical Logic Modules Medical Logic Modules (MLMs)(MLMs) Medical Logic Modules (MLMs) encode medical
knowledge which are used in decision-support systems.
Sharing knowledge gives way to many obstacles. Typically medical institutions do not share the
same decision support systems. Sharing knowledge across institutions,
coordinating local vocabularies and translating the logic for automation is a strenuous process.
Arden SyntaxArden Syntax The Arden Syntax is a Medical Logic Module that
has been developed for the task of sharing medical knowledge bases across many institutions.
Its main focus is on knowledge used in decision support systems that can provide therapeutic suggestions and alerts.
It is compiled and then run automatically to generate advice where and when it is needed.
Arden SyntaxArden Syntax
Contains three main sections: maintenance, library and knowledge.
Maintenance section contains management information such as title,
filename, author, etc. Library section
commenting section where the purpose of the MLM is described.
Arden SyntaxArden Syntax
Knowledge section contains few subsections type section--describes the way the
MLM is to be used. data section--assigns local variables,
which can be lengthy database queries
evoke slot--contains the conditions under which the MLM becomes active.
Arden SyntaxArden Syntax logic section--consists of the actual
rule or medical condition to test for action section—describes what is to
be done when the condition is true.
knowledge:type: data-driven;data:
/* absolute neutrophile count */
anc := read last 2 from ({query
for ANC} where it occurred within the past 1 week);
pt_taking_tms := read exist {query for TMS order};
evoke: on storage of {ANC};logic:
if pt_taking_tms /*1*/and last anc < 1000 and decrease of anc > 0 then
conclude trueelse
conclude false;action: store "Caution: The
patient's relative granulocytopenia may
be exacerbated by
trimethoprim/sulfamethoxazole.";
In the data slot, the local variable "anc" is assigned the patient's last 2 ANC's
within the past week. "pt_taking_tms" is
assigned true or false depending on whether the patient is taking
trimethoprim and sulfamethoxazole (TMS).
The evoke slot specifies that this
MLM is evoked whenever an
absolute neutrophile count
(ANC) is stored
The logic slot says that if the patient is taking TMS and if the last ANC is less than 1000 and if the ANC is decreasing, then execute the action slot, which sends the appropriate message.
Arden Syntax and SIPArden Syntax and SIP
Two possible ways of using Arden Syntax with SIP Users subscribe to Arden Syntax rules already
implemented Users subscribe to Arden Syntax rules
dynamically
Arden Syntax and SIPArden Syntax and SIP Users can subscribe to an Arden Syntax rule
already implemented in a server. Participants within the monitoring system are
aware of the Arden Syntax rules within each institution.
SIP SUBSCRIBE is sent with the message body containing the name of the rule being subscribed to
The server executes this rule within its system and notifies the subscriber whenever that particular rule becomes true.
Arden Syntax and SIPArden Syntax and SIP Arden Syntax rules dynamically added within a server’s
knowledge base for monitoring purposes. In this example, a subscriber inserts the rule itself within
the SUBSCRIBE message body. The server receives the SUBSCRIBE message and
extracts the message body, compiles the syntax and then executes the logic within the syntax.
The server will monitor the database and whenever the syntax becomes true, it will invoke the action specified within the rule via a SIP NOTIFY message.
Arden Syntax and SIPArden Syntax and SIP
Drawbacks of this method Since institutions each have their own
custom databases, adding a dynamic syntax rule may result in incompatibility with the database that is being queried to.
Unless the subscriber knows the exact query language of the remote server’s database, this will not work.
XML Messages and SIPXML Messages and SIP XML (Extensible Markup Language) is
“metalanguage”, which is a language used for describing other languages
An XML schema is an XML language that defines various data types found in the XML document
Popular in web-related programming Good choice for interoperability within many
different types of institutional systems.
XML Messages and SIPXML Messages and SIP XML messages may be used for representing
database query a filter for events subscribed to specification of alerting methods performing remote procedure calls.
XQL (XML Query Language)-- general-purpose query language that is being standardized within the W3C
Used to query a remote database assuming a common XML schema is shared
XQL document is processed automatically within the notification server by interpreting the XQL document and translating it to its own database query language.
Bluetooth and SIPBluetooth and SIP Bluetooth is a specification that uses low-power radio
signals to link phones and computers Use of Bluetooth is being considered in the medical industry Companies such as Colorado MEDtech and Code Blue
Communications Inc. are developing bluetooth-enabled medical devices.
These devices provide mobile access to information and medical data
acquisition. enables devices to communicate with each other
wirelessly. Bluetooth can also be used for location-based services such
as detecting the doctor’s whereabouts or for establishing ubiquitous systems in the hospital environment.
1)Doctor subscribes to server to monitor patient’s heart
Bluetooth access point
4)Doctor can’t be reached so doctor’s location is
identified via his bluetooth-enabled PDA and patient’s data is also transmitted to the PDA
Bluetooth access point
3)Server process data that results in a notify being sent to the doctor’s pager
2)Heart monitor
transmits signals
wirelessly to the server
Location information sent
5)Server calls house phone near the doctor
BenefitsBenefits Device Neutrality
There are likely to be range of SIP-based end systems, ranging from IP telephones, 3G wireless handsets, IM/presence software to embedded devices.
Event monitoring system can be easily extended to new devices
More Information and Automated Action Video conferencing, text messaging Device control which causes flashing lights
and aides the hearing-impaired
ConclusionConclusion SIP is a signaling protocol that
supports SUBSCRIBE/NOTIFY methods SIP-based medical event monitoring
system can be implemented using MLMs or XML messages
SIP provides a flexible and robust event notification architecture in conjunction with other wireless protocols
