Units of Measurement

quantities and units

• UCUM• Units in RTM• IHTSDO - Observable and Investigation Model Project

• ISO/IEC 80000 / 80003 - telebiometrics• (IDMP, ISO 11240)

from draftISO/CD 11240

UCUMThe Unified Code for Units of Measure

• Codes for base units and derived units• Covers most units in practical use• freely available• published as XML file• lightweight maintenance process • unitsofmeasure.org

UCUM

• added units for RTM:– Wood units for vascular resistance:

[wood'U] := mm[Hg].min/L– B[10.nV] ( for using dB[10.nV] )

• future development:– add syntax rules for logarithmic units– rules for arbitrary units– road to ISO?

Lab: Reference ranges for blood tests

Unit alone is not enough!

• relative volume:1 L / 2 L = 0.5 L/L

• volume fraction:1 L / 3 L = 0.333 L/L

• same unit and dimension!

-> fully specified property required!

1 L

1 L

1 L

harmonized RTM table

IHTSDOObservable and Investigation Model Project

Example: • substance rate of renal excretion of

pregnanediol in micromoles per day (observable entity)– PROPERTY TYPE substance rate– CHARACTERIZES renal excretion of pregnanediol– PROCESS OUTPUT pregnanediol– UNITS micromoles per day– DIRECT SITE urine specimen

IHTSDOObservable and Investigation Model Project

Example: • mass concentration ratio of silver to creatinine in 24

hour urine (observable entity)– PROPERTY TYPE mass concentration ratio– CHARACTERIZES renal excretion of silver– PROCESS AGENT renal parenchyma– PROCESS DURATION 24 hours– PROCESS OUTPUT silver– RELATIVE TO creatinine– DIRECT SITE 24 hour urine specimen

IHTSDOObservable and Investigation Model Project

• PROPERTY TYPE • INHERES IN

– INHERENT LOCATION – INHERENT INGREDIENT

• CHARACTERIZES – PROCESS AGENT – PROCESS DURATION– PROCESS OUTPUT

• TOWARDS• RELATIVE TO, REL-TO PART-OF

IHTSDOObservable and Investigation Model Project

• PRECONDITION• SCALE• UNITS• TECHNIQUE• DIRECT SITE

observable

PROPERTY TYPE Property types

PROCESS DURATION

SCALE

Time frame

Scale types

DRAFT model for observables with a target that is a ‘quality’

independent continuantsINHERES IN

TOWARDS Functions, substances

UNITS units

TECHNIQUE techniques

OBS-TARGET

PRECONDITION Body states (challenges, fasting etc.), timings, sequence numbers, etc

DIRECT SITE Body structures, specimens

quality

sitesHAS LOCATION

substancesHAS INGREDIENT

RELATIVE TO substances

IHTSDOObservable and Investigation Model Project

• Property Type– This attribute is used to specify the type of

inherent quality or process that is to be observed.– Its values are abstract types of quality (length,

odor, concentration) or abstract types of process features (rate, speed), and do not include qualities that are located (length of arm, odor of urine), or given a value (elevated concentration).

IHTSDOObservable and Investigation Model Project

• Note: In a coming release of SNOMED CT, Measurement property will become a subtype of a new general concept Property type (qualifier value)

IHTSDOObservable and Investigation Model Project

• Working on Rules for translating LOINC names and cNPU codes into the SNOMED observables model.

• Viable approach for parts of 11073 nomenclature?

• Relation to RTM?

ISO/IEC 80000

• Quantities and units • Successor of ISO 31, IEC 60072• definitions, names, letter symbols and their

use, relations, and signs and symbols used with them

• ISO TC 12 - Quantities and Units / IEC TC 25• "style guide" for scientific publications

ISO/IEC 80003

• ISO TC 12 - Quantities and Units

• ISO 80003: Physiological quantities and their units– ISO 80003-2 PHYSICS– ISO 80003-3 CHEMISTRY– IEC 80003-4 BIOLOGY– IEC 80003-5 CULTUROLOGY– IEC 80003-6 PSYCHOLOGY