Liberating medical device data
for clinical research
An architecture for
semantic and temporal harmonization
Assistant Professor Anesthesiology & Critical Care Medicine The Johns Hopkins Medical Institutions Baltimore, MD 2224-2760
IEEE Senior Member & CTO & VP Clinical Applications Nuvon, Inc. 3624 Market St., Philadelphia, PA 19104
Application Development Engineer Nuvon, Inc. 3624 Market St., Philadelphia, PA 19104
Rafael Richards, MS, MD John R Zaleski, PhD Sameer Peesapati, MS
Introduction: The State of Device Data
2
Medical Device Data: The Problem
3
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
Introduction
4
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
Architecture
5
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.
Nuvon VEGA Server
IDM-MG 3000
IDM-MG 4000
Enterprise Clinical Information Systems /Electronic Medical Record Systems
IDC
NativeData
NativeData
NativeData
NativeData
IDM-SpecificHL7 Data
HL7 Data
Infusion Pumps
Physiological Monitors
Ad-Hoc Vitals Monitors
Mechanical Ventilators
Nuvon VEGA Server
IDM-MG 3000
IDM-MG 4000
Enterprise Clinical Information Systems /Electronic Medical Record Systems
IDC
NativeData
NativeData
NativeData
NativeData
IDM-SpecificHL7 Data
HL7 Data
Infusion Pumps
Physiological Monitors
Ad-Hoc Vitals Monitors
Mechanical Ventilators
DAG & MS DCA
Nuvon VEGA Server
IDM-MG 3000
IDM-MG 4000
Enterprise Clinical Information Systems /Electronic Medical Record Systems
IDC
NativeData
NativeData
NativeData
NativeData
IDM-SpecificHL7 Data
HL7 Data
Infusion Pumps
Physiological Monitors
Ad-Hoc Vitals Monitors
Mechanical Ventilators
.
.
.
Physical Architecture
Devices
DCA Device DAG
MS
Clinical
Information
System
CSV or TXT
HL7
Device
Drivers`
Network Time
Server
Logical Architecture
monitoring
Data file
push polled
Configuration
8
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
Time Synchronization
9
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.
Medical Device-1
Medical Device-2
Medical Device-
M
.
.
.
…
DCA DAG
Network Time
Service
UTC UTC
Text
EMR
10
Obtain Device
Measurements
RkRkRk ttt
RRk tt RRRk ttt and
kkk ttt
PCD k = 1 Output Auto poll
DCA DAG
(end of flow) (start of
data query)
)( kk tx )( RR tx
RRR ttt
0ttk )( kk tx
Rkk tt RkRkk ttt and
Output PCD
Measurements such that
Output PCD
Data such that
)( Rkk tx
Aggregator Manual frequency
Obtain Device
Measurements
RkRkRk ttt kkk ttt
Auto
(start of
data query)
)( kk tx0ttk
)( kk tx
Rkk tt RkRkk ttt and
Output PCD
Measurements such that
Manual PCD k = 2
.
.
.
Obtain Device
Measurements
RkRkRk ttt kkk ttt
Auto
(start of
data query)
)( kk tx0ttk
)( kk tx
Rkk tt RkRkk ttt and
Output PCD
Measurements such that
Manual PCD k = M
Time Sync Process
11
Device 1 Reporting Time
Device 2 Reporting Time
Device M Reporting Time
.
.
.
Common Reporting Time
tR
tR1
tR2
tRk
Selecting Common Reporting Time
12
Device 1 Reporting Time
Device 2 Reporting Time
Device M Reporting Time
.
.
.
Common Reporting Time t0 t1
tR
NULL
Reporting When No Data Exist
13
Terminology Synchronization
14
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.
Medical Device-1
Medical Device-2
Medical Device-
M
.
.
.
…
DCA DAG
Network Time
Service
UTC UTC
Text
EMR
Parameters:
Device-1:
A1, A2, A3, …
Device-1:
B1, B2, B3, …
Device-1M
M1, M2, M3, …
Master Dictionary:
A
B
C
D
E
F
.
.
.
A1
A2
A3
…
B1
B2
B3
…
…
M1
M2
M3
…
15
HR
SpO2
NBPs
NBPd
NBPm
ARTs
ARTd
ARTm
CO
PVC
etCO2
…
HR
SpO2
fR
Mve
Tve
fRe
PIP
etCO2
…
HR-ECG
NBPs
NBPd
NBPm
RR
MVe
TVe
Device 1
Device 2
User-Selected Mapped Output
SpO2-1
SpO2-2
HR-SPO2
User-defined Mapping
16
Terminology Sync
17
cbcb xxx
Rx
Y
cbx~
nullxcb
cbcbcb xxx
U
cbcbcb xxx~~
U cbx~
N
User defined Auto defined` Input
Output Union
Data Output
18
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.
Device 1
Device 2
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
Patient
information
from ADT
(optional)
Parameter
selection and
periodicity of
measurements
DCA DAG
CSV FILE +
HL7
19
CSV Output
20
Time measured from start of data collection (seconds)
CSV Data Plot
21
Time synchronized
Conclusions
22
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.
Nomenclature
23
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.
Nomenclature
24
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.
Nomenclature
25
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.
Medical
Device
Software
functions
DCA
Proprietary
(RS232)
Text
(TCP/IP)
Database
DAG,
MS
NTS
Symbols
26
control
(TCP/IP)