Liberating medical device data for clinical research
1. Liberating medical device data
for clinical research
An architecture for
semantic and temporal harmonization
Rafael Richards, MS, MD John R Zaleski, PhD Sameer Peesapati, MS
Assistant Professor IEEE Senior Member & Application Development Engineer
Anesthesiology & Critical Care Medicine CTO & VP Clinical Applications Nuvon, Inc.
The Johns Hopkins Medical Institutions Nuvon, Inc. 3624 Market St., Philadelphia, PA 19104
Baltimore, MD 2224-2760 3624 Market St., Philadelphia, PA 19104
3. Medical Device Data: The Problem
Medical device data are trapped in silos
Unique Protocols
Unique Physical Connectivity
Unique Clock Times
Unique Time frequency of output
Unique Terminology
Differences must be harmonized before data can be
used
3
4. Introduction
We present a tool that:
Liberates device data
Integrates data from multiple devices
Semantically and temporally harmonizes data from as
many as eight medical devices connected to a given
patient
Data are delivered to the clinical investigator in
multiple formats
CSV (spreadsheet) or HL7
4
5. Architecture
Data collection appliance (DCA)
Each DCA can be connected to as many as eight patient physiologic
monitoring or therapeutic medical devices.
DCA can be remotely accessed via hospital network to select
parameters and frequency of collection from devices connected to
the patient.
Data aggregation gateway (DAG)
DAG orchestrates integration of data of from multiple patients
Filters and synchronizes data such that it can be easily stored in a
data warehouse (DW) or EMR.
Management Server (MS)
Orchestrates coordination of data between each bedside and DAG.
Functions include time synchronization of all devices at all bedsides
to a single universal clock, and use of a standard dictionary to
harmonize terminology.
5
6. Nuvon VEGA Server
Physical Architecture
Mechanical Ventilators
Native
Devices Data DCA DAG & MS
IDC
Nuvon VEGA Server
Enterprise Clinical Information System
IDM-MG 3000 Electronic Medical Record Systems
Native
Data
Ad-Hoc Vitals Monitors Nuvon VEGA Server
Mechanical Ventilators
Native
Native
Data
Data IDC
Enterprise Clinical Information Systems /
IDM-MG 3000 IDM-Specific Electronic Medical Record Systems
HL7 Data
Native HL7 Data
Native
Data
Mechanical Ventilators Data
Ad-Hoc Vitals Monitors Native
Physiological Monitors
Data
. Native IDC
. Data Enterprise Clinical Information Syste
. IDM-MG 3000 Electronic Medical Record System
IDM-Specific IDM-MG 4000 Data
HL7
Native HL7 Data
Native
Data
Data
Infusion Pumps
Physiological Monitors
Ad-Hoc Vitals Monitors
Native
Data IDM-MG 4000
Infusion Pumps
IDM-Specific
HL7 Data
HL7 Data
Native
Data
7. Logical Architecture
MS
Device monitoring
Drivers`
CSV or TXT
Data file
DAG
Device DCA
polled push
HL7 Clinical
Information
System
Network Time
Server
8. Configuration
DCA is accessible via its web page through laptop of
DAG
Through this web page, parameters may be included or
excluded from offered set (or completely replaced relative to
the offered set).
Note that parameter description, its code, and units of measure
are defined at this level with respect to specifications of
manufacturer.
At DAG it is possible to alter parameters
Common codebook allows parameter semantic synchronization
so that user can receive these parameters in unified codes that
are desired by user
Parameters are synchronized in time for output so all data from
single patient aligned with one UTC time increment
8
9. Time Synchronization
Each device collects data in accord with its own time
clock.
Data are aggregated and are written out synchronized to
a single clock at DAG.
Each medical device has a separate clock—not
synchronized with any universal clock or with each other.
Each medical device is polled at a separate frequency.
As data are collected on each DCA, these clocks are
aggregated locally: that is, data are packaged for
transmission to DAG along with DCA time stamp—UTC.
Finally, on DAG, times of individual devices are
synchronized according to a universal, UTC-based
clock.
9
10. Network Time
Service
Medical Device-1
UTC UTC
Text
DCA DAG
Medical Device-2
…
EMR
.
.
.
Medical Device-
M
10
11. Time Sync Process
DCA DAG
Auto poll Manual frequency Aggregator Output
PCD k = 1
Obtain Device x k (t k ) Output PCD x k (t Rk ) Output PCD
t k t0 Measurements
Measurements such that Data such that
x R (t R )
x k (t k ) tk t Rk and tk t Rk t Rk t Rk t R and t Rk t R t R
(start of (end of flow)
data query)
tk tk tk t Rk t Rk t Rk t R t R t R
Auto Manual
PCD k = 2
Obtain Device x k (t k ) Output PCD
t k t0 Measurements
Measurements such that
x k (t k ) tk t Rk and tk t Rk t Rk
(start of
data query)
tk tk tk . t Rk t Rk t Rk
.
Auto . Manual
PCD k = M
Obtain Device x k (t k ) Output PCD
t k t0 Measurements
Measurements such that
x k (t k ) tk t Rk and tk t Rk t Rk
(start of
data query)
tk tk tk t Rk t Rk t Rk
11
12. Selecting Common Reporting Time
tR1
Device 1 Reporting Time
tR2
Device 2 Reporting Time
.
.
. tRk
Device M Reporting Time
Common Reporting Time
12
tR
13. Reporting When No Data Exist
Device 1 Reporting Time
NULL
Device 2 Reporting Time
.
.
.
Device M Reporting Time
tR
Common Reporting Time
t0 t1
13
14. Terminology Synchronization
Master codebook is stored on DAG.
Updated by driver specifications of each device and is modified
and maintained within DAG in data file format.
It is modified by user to user-defined specifications.
Dictionary is linked to individual device dictionary through
codebooks that map the device-specific parameters to a common
codebook.
Devices have their data vectors mapped to common unified
codes representing specific data elements within master
codebook.
Parameters from each device may be mapped to common unified
codes within codebook.
Therefore, this codebook establishes a common dictionary of
terms that are then written out to file or as HL7 messages to end
user clinical information systems.
14
15. Parameters: Network Time
Service
Medical Device-1
Device-1:
UTC UTC
A1, A2, A3, …
Text
DCA DAG
Medical Device-2
…
Device-1:
B1, B2, B3, … EMR
Master Dictionary:
. A1 A
. A2 B
. A3 C
… D
Medical Device-
M E
B1
B2 F
Device-1M B3 .
M1, M2, M3, … … .
… .
M1
M2
M3
…
15
17. Terminology Sync
Auto defined` User defined Union Output
Input
~
x cb
Y
x cb null
~ ~ ~
xR x x cb x cb x cb x cb U x cb x cb
N
x cb x cb U x cb
17
18. Data Output
Output data are written to a comma-delimited
format file in a local directory on the DAG laptop.
Data between the DCA and DAG are constructed
using three separate elements
(1) Patient Info Table;
(2) Param Header Table;
(3) Param Values Table.
18
19. Patient Name(32)+0x2c Patient ID(32)+0x2c Bed Location(32)+0x2c Device Name(32) +0x2c 0x0d 0x0a
Parameter Header:
DCA_TS + 0x2c Chosen Device Parameter Codes and separated by comma (n*paramlen+(n-1) 0x2c(commas)) 0x0d 0x0a
Param Values: This is the protocol for each MSH Segment—
DCA_TS_value+0x2c Chosen Device Parameter Values (n*value_len+(n-1) 0x2c (commas)) 0x0d 0x0a
…N Parameters
Device 1
DAG
DCA
Device 2
CSV FILE +
Parameter
HL7
Patient
information selection and
from ADT periodicity of
(optional) measurements
19
21. CSV Data Plot
Time synchronized
Time measured from start of data collection (seconds)
21
22. Conclusions
A tool has been developed that acquires all
data from up to eight patient care devices
connected to a patient
Tool semantically and temporally
harmonizes and generates a readily useable
spreadsheet of time synchronized data that
can be imported to any statistical analysis
software.
This tool should greatly enhance the
capabilities of clinical investigators to do
physiologic research.
22
23. Nomenclature
PoC Point of Care: physical location at bedside proximity of patient.
DCA Data Collection Appliance: physical device containing 8 serial ports that
communicates with the medical devices at the point of care.
DW Data Warehouse: repository for locating, storing, and retrieving data.
EMR Electronic Medical Record: ―a longitudinal collection of health information
in electronic format for and about persons‖ – derived from the 2003 IOM
Patient Safety Report.
DAG Data Aggregation Gateway: the system component that receives
disaggregated patient care data from DCAs and aggregates, formats,
synchronizes and harmonizes these data for communication to an EMR or
for writing to a DW or a file.
23
24. Nomenclature
MS Management Server: software that maintains a repository of device
drivers used by the DCA to communicate with medical devices; maintains
a web server that enables viewing individual DCAs and DAG through Web
pages; manages a database server and receives health and status of
DCAs and DAG for presentation in a web dashboard to facilitate general
management and oversight of the system.
HL7 Health Level Seven: a non-profit organization that maintains a collection
of interoperability standards associated primarily with data communication
and interoperability of healthcare systems.
ORU^R01 Observation Request-Unsolicited Results Transaction: one of
several HL7 formatted transactions used in standard practice to
communicate observations such as measurement data obtained from
medical devices.
WiFi Term used to describe wireless communication.
RJ45 A registered jack connector and wiring pattern normally used for
connecting computers and similar appliances over high-speed networks.
24
25. Nomenclature
O/S Operating System: based set of programs that operate the hardware of
a computer hardware resources.
PACU Post Anesthesia Care Unit: an area within a hospital that typically
adjoins the surgical area in which patients are moved to recover from
the effects of anesthesia.
MB MegaByte: 220 Bytes or 1048576 bytes.
DB-xx Designation of port connectors for attaching devices serially to
computers. Common connectors are DB-9 (9 pin serial connector, either
male or female), DB-15 (15 pin connector), etc. These connectors are
used to interface RS-232 connections with said computers.
UTC Coordinated Universal Time: is a time standard based on international
Atomic Time.
XML Extensible Markup Language: a standardized and flexible mechanism
for sharing information formats following a format standard designed for
Web-based documents.
Vector An array of scalar values with each value representing a different
attribute of a unique object, with device and UTC time stamp appended.
25
26. Symbols
DAG,
Medical
Device
DCA MS
NTS
Software
functions Database
Proprietary control Text
(RS232) (TCP/IP) (TCP/IP)
26
