HL7 Version 3 Resources
HL7 V3 Resources
What is HL7 Version 3?
HL7 Version 3 is used by healthcare computers to talk to other computers. The name HL7 comes from 'Healthcare' and the top level (Level 7) of the Open Systems Interconnection (OSI) model, which carries the meaning of information exchanged between computer applications. HL7 Version 3 is mainly used in large interoperability projects, such as the NHS Connecting for Health programme in the UK, Health InfoWay in Canada, etc. HL7 V3 has significant differences from HL7 Version 2, which is mainly used within individual hospitals. Browse 'Introduction to HL7' V3 Books and Guides here..
HL7 V3 Introduction & Information
What is HL7? A simple introduction to the Health Level 7 eHealth Standards
What is Health Level 7? A comprehensive HL7 Overview (WikiPedia)
What is HL7 International? The official site of the HL7 organisation
HL7 Books & eHealth Books we Recommend:
Download the HL7 Standards - CDA, V2.x, V3, Arden Syntax & EHR Functional Model
NEW: Meaningful Use and Beyond: A Guide for IT Staff in Health Care - Are you ready to take your IT skills to the healthcare industry? This concise book explains how the US healthcare system is implementing Electronic Health Records ("EHRs") and other IT systems to comply with the US government’s Meaningful Use requirements. A tremendous opportunity for tens of thousands of IT professionals, the Meaningful Use program requires a complete makeover of archaic paper records systems, cumbersome workflows and other outdated practices. This book describes in detail how hospitals and doctors’ offices differ from other organizations that use IT and explains how to bridge the gap between clinicians and IT staff.
Electronic Health Records For Dummies - a helpful, plain-English guide for doctors, nurses and healthcare administrators to understand, implement and use an Electronic Health Record system.
Health Care Information Systems: A Practical Approach for Health Care Management - the Best Selling textbook in the field. Mark Leavitt, MD, PhD, CCHIT Chairman said "With health care information technology now in the national policy spotlight, this book should be required reading for every health care administrator and student.
The HL7 CDA Book - by eminent expert Keith Boone provides clear and easy-to-use CDA implementation guidance with numerous examples. The reader will learn not only how to implement the CDA standard, but also to understand its idioms and to "speak" the CDA language.
Introduction to HL7 V2.x Messaging (2nd Edition) - the most popular HL7 V2.x Messaging introductory Textbook. Mike Henderson is widely recognized as a most experienced HL7 V2.x teacher and trainer. He regularly teaches at the HL7 Education Summits in the US and co-authors the HL7 V2.x Analyst Certification exams.
HL7 V2.x Messaging Study Guide - the Study Guide to the above Textbook. Both books are considered mandatory reading and study for candidates sitting the HL7 International V2.x Analyst Certification exam.
Verification Results for IT Standards: HL7 - a text focussing on the formal verification of standards in healthcare.
Principles of Health Interoperability HL7 and SNOMED - Healthcare depends on the two leading standards HL7 and SNOMED CT for functional and semantic interoperability. Tim is one of the most experienced teachers of both HL7 V3 and SNOMED CT.
International Standards Online: ISO, ANSI, IEC, IEEE, CSA, BSI, DIN, etc. - easily and instantly download these popular eHealth Standards!
Managing Health Care Information Systems: A Practical Approach for Health Care Executives - the title says it all!
Browse more HL7 Books and Manuals to learn the Secrets of Health Level 7.
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Why is HL7 needed?
A specialised healthcare language is required to avoid the sort of ambiguity that is common in everyday medical English. Computers cannot easily deal with synonyms (saying the same thing using different words) or homonyms (where the same term or phrase means different things depending on context). Furthermore, healthcare data is uniquely complex in scope and structural complexity. Joined-up healthcare is difficult when patients have multiple problems and are being treated by several specialists in different locations.
HL7 and XML
HL7 messages are XML documents, which look somewhat similar to HTML. Each message is a string of text with information enclosed by tags, wrapped in angle brackets. Start tags look like <tag> and end tags look like </tag>. Tags can be qualified by attributes such as <tag attribute="value">.
The HL7 tags and attributes are derived from the HL7 Reference Information Model (RIM) and the HL7 Data Types. The structure of each HL7 message is set out in an XML schema, which specifies the tags and attributes needed or allowed in the message, their order and the number of times each may occur, together with annotations describing how each tag shall be used.
The HL7 RIM Reference Information ModelHL7 is a language, and every language has a grammar. The HL7 RIM (Reference Information Model) specifies the grammar of HL7 messages and, specifically, the basic building blocks of the language and their permitted relationships. The RIM is not a model of healthcare, although it is healthcare specific, nor is it a model of any message, although it is used in messages. At first sight the RIM is quite simple. The RIM backbone has just five core classes and a number of permitted relationships between them.
In HL7 V3, every happening is an Act, which is analogous to a verb in English. Each Act may have any number of Participations, in Roles, played by Entities. These are analogous to nouns. Each Act may also be related to other Acts, via Act-Relationships.
Act, Role and Entity classes also have a number of specialisations. For example, Entity has a specialisation called Living Subject, which itself has a specialisation called Person. Person inherits the attributes of both Entity and Living Subject.
RMIM Refined Message Information ModelHL7 has developed a notation, called Refined Message Information Model (RMIM), which displays the structure of a message as a colour-coded diagram. Most RMIMs can be shown on a single sheet of paper or PowerPoint slide and these RMIM diagrams are used to design messages and to explain what each HL7 message consists of.
Structural AttributesStructural attributes are used to specify more precisely what each RIM class means when used in a message. For example, Act has a class code and a mood code. The class code states what sort of Act this is, such as an observation, an encounter, or the administration of a drug. Mood is analogous to the tense of a verb. Mood code indicates whether an Act has happened (an event), or is a request for something to happen, or a goal or even a criterion. For example, "weight = 100kg" is an observation event; "measure weight daily" is a request; "reduce weight to 80Kg" is a goal and "if weight is greater than 80Kg" is a criterion.
Attributes and Data TypesThe RIM defines a set pre-defined Attributes for each class and these are the only ones allowed in HL7 messages. Each attribute has a specified Data Type. These Attributes and Data Types become tags in HL7 XML messages.
RefinementMessage specifications, to do a particular task, use a sub-set of the available RIM Attributes, listing each element used and how many repeats are allowed. This is known as refinement. Each Data Type is constrained to the simplest structure that meets the requirements of the task.
Identifiers and CodesOne common data type is the Instance Identifier, which is used to give unique identity to people, persons, organisations, things and information objects. HL7 uses two main types of code. The first type covers the specialised codes used for structural attributes and are defined by HL7 itself. The second type covers externally defined terms and codes such as SNOMED CT (Clinical Terms).
Scope and ExtensibilityHL7 covers the whole scope of healthcare communications in an unambiguous way, using a relatively small set of constructs, which need to be learnt. Healthcare communications are complex and any language needs to accommodate this complexity and also handle future needs.
(Text: Tim Benson, HL7 UK)
HL7 International runs regular HL7 eLearning courses for people wanting to study HL7 V3 and CDA by distance education. Where possible, the Australian students are tutored by local staff. Other organisations provide comprehensive HL7 education.
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