# Logical Record Architecture for Health and Social Care
## Discharge Summary Release 0.02

Contents
The content of this release is not comprehensive and is not fully validated and must not be used in live system implementations.
# ELEMENT Domain Model: Kt/VObservation
An ELEMENT to represent a derived Kt/V observation. Kt/V is a measure of haemodialysis adequacy. Kt/V can be predicted from one of several simple formulae requiring as input data the pre- and post-dialysis urea concentrations, the duration of dialysis, and the weight loss during dialysis. Kt/V can be calculated using several formulae giving different results and hence, if Kt/V is being used for comparative audit, it is important that the raw data are collected to allow calculation of URR and estimated Kt/V using a single formula. The result of a Kt/V calculation may be inclusive of the subject of care's residual kidney function. ## Attributes
Name | Data type | Occurs | Description | Value Constraints
--- | --- | --- | --- | ---
name | SC | 1..1 | The name, expressed as a coded value or as plain text, specifies the clinical or administrative concept to which this EHR node corresponds, as labelled in the EHR system in which it was first committed. |
value
Literal value(s): PROPERTY_OBSERVATION_ELEMENT
rc_id | II | 1..1 | The globally-unique identifier by which this node in the EHR hierarchy is referenced in the EHR system to which the data were first committed. This identifier shall be retained by the EHR Recipient and re-used whenever this RECORD_COMPONENT is subsequently included in another EHR_EXTRACT. |
meaning | CD.CV.SCT | 1..1 | A coded representation of a Kt/V derived observation. |
code
Semantic expression constraint
synthesised | BL | 1..1 | This attribute value shall be TRUE if this RECORD_COMPONENT has been created in order to comply with this standard , but this point in the EHR hierarchy has no corresponding node in the EHR from which it was extracted. |
value
Default value: true
obs_time | IVL_TS | 0..1 | The date and time, or interval, of a Kt/V observation. |
value | REAL | 1..1 | The value of the derived Kt/V observation. Kt/V is by definition dimensionless. |
## COMPONENT RELATIONSHIPS ### Subject of relationships
Name | Object of relationship | Occurs | Dependency
--- | --- | --- | ---
HasAnnotation | Text | 0..* | INDEPENDENT
IsDerivedObservation | UrineVolumeObservation | 0..* | INDEPENDENT
IsDerivedObservation | EstimatedBodyWaterCompositionObservation | 0..* | INDEPENDENT
IsDerivedObservation | WashbackVolumeObservation | 0..* | INDEPENDENT
IsDerivedObservation | UreaDistributionVolumeObservation | 0..* | INDEPENDENT
IsDerivedObservation | BloodUreaObservation | 0..* | INDEPENDENT
IsDerivedObservation | FluidIntakeVolumeObservation | 0..* | INDEPENDENT
IsDerivedObservation | HaemodialysisAccessRecirculationObservation | 0..* | INDEPENDENT
IsDerivedObservation | BodyWeightObservation | 0..* | INDEPENDENT
IsDerivedObservation | MaterialFlowRate | 0..* | INDEPENDENT
## Item of ENTRY Domain Models ### Kt/V ## Reference Model Type ## PROPERTY_OBSERVATION_ELEMENT