NPSG Data ExchangeWhere We Are Today and What We NeedDavid M. Rapoport, MDNYU School of MedicinePhiladelphiaJanuary 27, 2006What is an Electronic NPSG?Raw DataEvents (“scoring”)Patient Information and IDAssociated Data (video, tech notes, etc)Representations of Data(Windows)Data are usually collected to, and displayed from, a proprietary file format.Benefits of Standardized Electronic NPSG File FormatMulticenter StudiesCentralized reading from multiple acquisition formatsData DisseminationSharing of scored data and completed data sets (eg SHHS)Additional processing of previously collected dataRemote Access, eg via internetDependent on transmission and compression.ArchivingOld records/migration of data to new systems or new analysesRecord NPSG in Proprietary FormatConvert toStandard FormatConvert to AlternateProprietary FormatData TransmissionDisplay Score/ProcessReport Score/ProcessReportData Storage DisplayWhy Can’t We Do This Now?Most systems use proprietary data format for raw and scored dataStandards for data exchange exist (eg EDF), but….Often used as “intermediate” data format for RAW DATA ONLYRules for using the “standard” are frequently incompletely implementedStandards for event and scored data incompletely or not definedNew solution for each new problem or advance in the field (lack of extensibility)Examples of Issues in Implementing EDFDates 02-05-05 February 5, 2005 or May 2, 2005?Sampling frequency – non integer causes “clock drift” if roundedCalibration information often lostInteger “wraparound” – maximum values that can be stored are -32,768 to +32767Loss of calibration2550Example of Wrap-aroundStandardization TargetsStandardized file format for dataStandardization of what a program utilizing the “standard” data can/must doRead dataWrite file or dataDisplay data (including processed data)Manipulate dataComponents of an Electronic NPSGRaw DataTime series of data pointsInformation about what data is, sampling freq, calibration, display, etcConventions on storageParallel or multiplexed data points for multiple channelsData compressionData integrity (watermarking)Examples: EDF, SDF, ASCII, proprietary binary formatsComponents of an Electronic NPSGEvents (eg apneas, sleep stages)Several CategoriesNo fixed set of eventsLinkages between eventsExamples: EDF plus, ASCII, proprietary binary formatsEvent “Categories” in Electronic NPSGDiscrete Events (eg scoring that occurs intermittently or not at all)Examples include apnea, hypopnea, arousalContinuous Descriptors (eg – scoring that always has a value)Changes occuring at Fixed Intervals (eg R&K epochs of sleep staging)Changes occuring at Variable intervals (eg position)Linkages between events – can either change an event or only qualify it Examples include different definitions of hypopnea (with arousal or desat)Development of a New NPSG Standard FormatPerspectives and Input neededResearchClinical PracticeNIH (Regulatory)IndustryProcedures to disseminate/implement a
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