HL7

1
HL7

• Version 2.3.1

2
Outline

• Introduction
• Concepts
• Examples
• Chapters

3
Introduction

• Level 7 ? Application level of OSI
• Purpose
• facilitate communication in healthcare settings
• by providing standards for exchange of data among
  healthcare applications

4
Introduction

• Version 2.3.1 is largely silent about privacy
  authentication and confidentiality of data that
  pass through messages
• makes no assumption about the ultimate use of
  data (but assumes that both source and
  destination applications provide for these
  requirements)
• Version 2.3.1 is silent on the actual logical and
  physical construction of the patient longitudinal
  health record

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Introduction

• HL7 makes no assumptions about the ownership of
  data
• HL7 makes no assumptions about the design or
  architecture of the receiving application system
• The scope of HL7 is restricted to the
  specification of messages between application
  systems, and the events triggering them

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Concepts

• Trigger event ? an event in the real world of
  healthcare creates the need for data to flow
  among systems
• Two types of data flow
• unsolicited update/acknowledgement
• query/result

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Concepts

• A message is the atomic unit of data transferred
  between systems
• Each message has a message type that defines its
  purpose
• For example, the ADT Message type is used to
  transmit portions of a patients Patient
  Administration (ADT) data from one system to
  another

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Concepts

• There is a one-to-many relationship between
  message types and trigger event codes
• a message type may be associated with more than
  one trigger event
• A message is comprised of a group of segments in
  a defined sequence

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Concepts

• A segment is a logical grouping of data fields
• A data field is a string of characters

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Examples

• Datatypes
• Message
• Segments

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Datatype (Coded Element) CE

• This data type transmits codes and the text
  associated with the code
• identifier ? which code
• text ? description
• name ? which coding scheme

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Datatype (Encapsulated Data) ED

• This data type transmits encapsulated data
• source application
• type of data
• data subtype
• encoding
• data

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Type of Data - ED
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Data subtype - ED
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Messages

• UDM/ACK - unsolicited display update message
  (event Q05)
• Trigger events for the unsolicited update are
  generally the completion of a particular action
  (concerning a given patient)
• a lab test might be completed

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Messages (Abstract message syntax)

• UDM Unsolicited Display Message Chapter
• MSH Message Header 2
• URD Results/Update Definition 2
• URS Results/Update Selection Criteria 2
• DSP Display Data 2
• DSC Continuation Pointer 2
• ACK General Acknowledgment Chapter
• MSH Message Header 2
• MSA Message Acknowledgment 2
• ERR Error 2

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Queries

• for data regarding a single patient, e.g., send
  all lab results for patient 123456
• for data regarding multiple patients, e.g., send
  the list of patients whose attending physician is
  Dr. 123
• for data that is not patient related, e.g., send
  the age specific normal values for serum protein.

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Queries

• The variety of potential queries is almost
  unlimited (embedded query languages, stored
  procedure calls, virtual table requests)
• There was no attempt here to define a Standard
  that would cover every possible query
• the Standard includes the most common queries
  that are likely to occur in a hospital

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Segment (MSH Message Header Segment)
Message Type Data field This field contains the
message type and trigger event for the message
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Chapters

• Patient Administration
• Order Entry
• Financial Management
• Observation Reporting
• Master Files
• Medical Records/Information Management
• Schedules
• Patient Care

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Patient Administration

• The Patient Administration transaction set
  provides for the transmission of new or updated
  demographic (nufus bilgisi) and visit information
  about patients

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ADT/ACK - admit/visit notification (event A01)

• An A01 event is sent as a result of a patient
  undergoing the admission process which assigns
  the patient to a bed
• It signals the beginning of a patients stay in a
  healthcare facility
• an A01 event can be used to notify
• the pharmacy system that a patient has been
  admitted and may be legitimately prescribed drugs
  
• nursing system that the patient has been admitted
  and needs a care plan prepared
• the finance system of the start of the billing
  period
• the dietary system that a new patient has been
  installed and requires dietary services
• the laboratory, pathology, and radiology systems
  that a patient has been admitted and is entitled
  to receive services
• the clinical repository that an admission has
  taken place for the EMR (electronic medical
  record)
• These compositions are left to developers

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ADT/ACK - admit/visit notification (event A01)

• ADT ADT Message Chapter
• MSH Message Header 2
• EVN Event Type 3
• PID Patient Identification 3
• PD1 Additional Demographics 3
• NK1 Next of Kin /Associated Parties 3
• PV1 Patient Visit 3
• PV2 Patient Visit - Additional Info. 3
• DB1 Disability Information 3
• OBX Observation/Result 7
• AL1 Allergy Information 3
• DG1 Diagnosis Information 6
• DRG Diagnosis Related Group 6
• PR1 Procedures 6
• ROL Role 12
• GT1 Guarantor 6
• IN1 Insurance 6

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AL1 - patient allergy information segment

• The AL1 segment contains patient allergy
  information of various types
• Each AL1 segment describes a single patient
  allergy

• Allergy type (IS) 00204 This field indicates
  a general allergy category. The standard suggests
  values for this datafield.
• - Allergy code/mnemonic/description (CE) 00205
  (Note that CE data type is used) This field
  uniquely identifies a particular allergy. This
  element may conform to some external, standard
  coding system (that must be identified), or it
  may conform to local, largely textual or mnemonic
  descriptions.

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AL1 - patient allergy information segment

• The AL1 segment contains patient allergy
  information of various types
• Each AL1 segment describes a single patient
  allergy

• Allergy type (IS) 00204 This field indicates
  a general allergy category. The standard suggests
  values for this datafield.
• - Allergy code/mnemonic/description (CE) 00205
  (Note that CE data type is used) This field
  uniquely identifies a particular allergy. This
  element may conform to some external, standard
  coding system (that must be identified), or it
  may conform to local, largely textual or mnemonic
  descriptions.

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Order Entry

• The Order Entry transaction set provides for the
  transmission of orders or information about
  orders between applications
• An order is a request for (Order Classification)
• clinical observations (e.g., vitals, IOs) from
  the nursing service
• tests in the laboratory
• food from dietary
• films from radiology
• linens from housekeeping
• supplies from central supply

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Financial Management

• The Finance chapter describes patient accounting
  transactions
• The patient accounting message set provides for
  the entry and manipulation of information on
• billing accounts,
• charges,
• payments,
• adjustments,
• insurance,
• and other related patient billing

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Observation Reporting

• These transaction sets permit the transmission of
  any kind of clinical observations including (but
  not limited to)
• clinical laboratory results
• the results of imaging studies
• EKG pulmonary function studies
• measures of patient status and condition
• vital signs
• intake and output
• severity and/or frequency of symptoms
• drug allergies
• problem lists
• physician and nursing history
• diagnostic lists
• physicals
• progress or operative notes
• and so on

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Master Files

• In an open-architecture healthcare environment
  there often exists a set of common reference
  files used by one or more application systems
• Such files are called master files
• Some common examples of master files in the
  healthcare environment include
• doctor master file
• system user (and password) master file
• location (census and clinic) master file
• device type and location (e.g., workstations,
  terminals, printers, etc.)
• lab test definition file
• exam code (radiology) definition file
• charge master file
• patient status master
• patient type master
• personnel, staff master file

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Medical Records/Information Management

• This chapter currently supports document
  management
• mainly, defines the Medical Document Management
  (MDM) transaction set
• It supports transmission of new or updated
  documents or information about their status(es)

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Schedules

• The goal of this specification is to facilitate
  the communication of scheduling requests and
  information between applications
• Schedules control the occurrence of certain
  services and the use of particular resources
• They consist of a set of open, booked and blocked
  slots for one particular service or resource
• Services are real-world events, such as clinic
  appointments
• Resources are tangible items whose use is
  controlled by a schedule. These items are
  often people, locations, or things low in supply
  but high in demand

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Patient Care

• The purpose of this chapter is to describe
  healthcare messages that need to be communicated
  between clinical applications for a given
  individual
• A goal refers to an objective to be achieved as a
  consequence of healthcare interventions applied
  to an individual
• A problem of a given individual can be described
  by formal diagnosis coding systems or by other
  professional descriptions of healthcare issues
  affecting an individual
• A clinical pathway is a standardized plan of care
  against which progress towards health is measured
  
• Variances are documented deviations, either
  positive or negative

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Patient Care Scenarios

• Patient pre-admission or patient admission
• A physicians office is scheduling a patient for
  admission to the hospital
• The admitting diagnosis/problem list and
  admission information is sent by the physicians
  electronic information system to the hospitals
  Patient Administration system and longitudinal
  medical record
• The trigger event identifies the message as an
  add problem to the Patient Administration and
  medical record system