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Liberating medical device data for clinical research
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Liberating medical device data for clinical research

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  • 1. Liberating medical device data for clinical research An architecture for semantic and temporal harmonizationRafael Richards, MS, MD John R Zaleski, PhD Sameer Peesapati, MSAssistant Professor IEEE Senior Member & Application Development EngineerAnesthesiology & Critical Care Medicine CTO & VP Clinical Applications Nuvon, Inc.The Johns Hopkins Medical Institutions Nuvon, Inc. 3624 Market St., Philadelphia, PA 19104Baltimore, MD 2224-2760 3624 Market St., Philadelphia, PA 19104
  • 2. Introduction: The State of Device Data2
  • 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 ServerPhysical ArchitectureMechanical 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 ServiceMedical Device-1 UTC UTC Text DCA DAGMedical 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 ofdata 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 ofdata 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 Time12 tR
  • 13. Reporting When No Data ExistDevice 1 Reporting Time NULLDevice 2 Reporting Time . . .Device M Reporting Time tRCommon 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 ServiceMedical Device-1 Device-1: UTC UTC A1, A2, A3, … Text DCA DAGMedical Device-2 … Device-1: B1, B2, B3, … EMR Master Dictionary: . A1 A . A2 B . A3 C … DMedical Device- M E B1 B2 F Device-1M B3 . M1, M2, M3, … … . … . M1 M2 M3 … 15
  • 16. User-defined Mapping Device 1 HR SpO2 NBPs User-Selected Mapped Output NBPd NBPm HR-ECG ARTs HR-SPO2 ARTd ARTm SpO2-1 CO SpO2-2 PVC etCO2 NBPs … Device 2 NBPd HR NBPm SpO2 fR RR Mve Tve fRe MVe PIP etCO2 TVe …16
  • 17. Terminology Sync Auto defined` User defined Union OutputInput ~  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 0x0aParameter Header:DCA_TS + 0x2c Chosen Device Parameter Codes and separated by comma (n*paramlen+(n-1) 0x2c(commas)) 0x0d 0x0aParam 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
  • 20. CSV Output20
  • 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. NomenclaturePoC 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. NomenclatureMS 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. NomenclatureO/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