HL7 RXV Segment: Pharmacy/Treatment Variance

The RXV segment was introduced in HL7 v2.7 to carry pharmacy/treatment variance data — particularly the bolus, patient-controlled analgesia (PCA), and max-dose parameters that surround a continuous infusion or PCA order. It travels with administration and variance reporting messages and gives downstream systems the dosing envelope that an infusion pump applied or attempted. RXV continues structurally through v2.7.1, v2.8, v2.8.1, and v2.8.2; this page reflects the v2.8.1 HAPI definition.

Purpose

RXV captures the dosing variance and PCA/bolus configuration tied to a single administration or pump program. It is produced by a smart pump, eMAR, or pharmacy system whenever a dose deviates from order, when a clinician programs a PCA or bolus, or when a max-dose lockout fires. The segment lets downstream surveillance and clinical decision-support engines analyze under/over-dosing patterns and reconstruct exactly how the device was programmed.

Typical uses:

Recording bolus type, amount, and volume for a PCA program.
Recording PCA type, dose amount, and dose volume per demand.
Capturing the max-dose limit, max-dose volume, and max dose per time the pump enforced.
Reporting lockout interval, syringe manufacturer/model/size, and an action code for variance reporting.

Used in

RXV carries pharmacy/treatment variance inside administration messages — most commonly Pharmacy/Treatment Administration (RAS) variance reporting and the related RDS dispense flow. A single RAS/O17 carries the order (RXO/RXE), the administration event (RXA), the dispense detail (RXR/RXC), and an RXV segment per variance or programmed PCA/bolus parameter set. RXV is also seen in custom infusion-pump interfaces feeding clinical surveillance platforms.

Field-by-field reference

The table below lists every field in RXV as defined by the HAPI v2.8.1 model. Seq is the dotted-identifier used in HL7 (RXV-1, RXV-2, ...). Req marks fields the standard requires; all others are optional and may be omitted. Repeat is Y where the field is defined as repeating in the v2.8.1 javadoc. Table # lists the HL7 user/HL7-defined table where one is well established.

Seq	Name	Data Type	Length	Req	Repeat	Table #	Description
RXV-1	Set ID - RXV	si	—	R	—	—	Sequence number for this RXV instance
RXV-2	Bolus Type	id	—	R	—	—	Coded type of bolus delivered
RXV-3	Bolus Dose Amount	nm	—	O	—	—	Quantity of drug per bolus dose
RXV-4	Bolus Dose Amount Units	cwe	—	O	—	—	Units for the bolus dose amount
RXV-5	Bolus Dose Volume	nm	—	O	—	—	Volume infused per bolus dose
RXV-6	Bolus Dose Volume Units	cwe	—	O	—	—	Units for the bolus dose volume
RXV-7	PCA Type	id	—	R	—	—	Coded type of PCA program
RXV-8	PCA Dose Amount	nm	—	O	—	—	Quantity of drug per PCA demand
RXV-9	PCA Dose Amount Units	cwe	—	O	—	—	Units for the PCA dose amount
RXV-10	PCA Dose Amount Volume	nm	—	O	—	—	Volume per PCA demand
RXV-11	PCA Dose Amount Volume Units	cwe	—	O	—	—	Units for the PCA dose volume
RXV-12	Max Dose Amount	nm	—	O	—	—	Maximum dose amount the pump allows
RXV-13	Max Dose Amount Units	cwe	—	O	—	—	Units for the max dose amount
RXV-14	Max Dose Amount Volume	nm	—	O	—	—	Maximum cumulative volume the pump allows
RXV-15	Max Dose Amount Volume Units	cwe	—	O	—	—	Units for the max dose volume
RXV-16	Max Dose per Time	cq	—	R	—	—	Maximum dose enforced per time window
RXV-17	Lockout Interval	cq	—	O	—	—	Minimum interval between PCA demands
RXV-18	Syringe Manufacturer	cwe	—	O	—	—	Manufacturer of the syringe in use
RXV-19	Syringe Model Number	cwe	—	O	—	—	Model number of the syringe in use
RXV-20	Syringe Size	nm	—	O	—	—	Nominal size of the syringe
RXV-21	Syringe Size Units	cwe	—	O	—	—	Units for the syringe size
RXV-22	Action Code	id	—	O	—	—	Variance action code for the segment

Most-used fields

RXV-1 Set ID - RXV — required sequencing; downstream parsers will reject unsequenced repetitions.
RXV-2 Bolus Type and RXV-7 PCA Type — required even when not in use; sites send a "none" or "N/A" code from their pump vocabulary.
RXV-3/4 Bolus Dose Amount + Units and RXV-8/9 PCA Dose Amount + Units — the dosing pair clinicians and pharmacists watch most closely.
RXV-16 Max Dose per Time — the only required CQ in the segment; carries the smart-pump's hard limit (e.g. 30^mg/4h).
RXV-17 Lockout Interval and RXV-22 Action Code — used to characterize PCA programs and to flag variance events for surveillance.

Version differences (2.6 to 2.8.2)

v2.6 — RXV does not exist. Pharmacy variance is carried implicitly in RXA-9 (administration notes) and free-text NTE.
v2.7 — RXV introduced with all 22 fields as defined here. Bolus Type, PCA Type, and Action Code are ID-typed and bound to user-defined vocabularies.
v2.7.1, v2.8, v2.8.1 — No new fields. CWE units fields are reaffirmed as the carrier for UCUM unit codes.
v2.8.2 — Structure unchanged; downstream IGs increasingly recommend explicit UCUM codes in every units field (RXV-4/6/9/11/13/15/21).

Common mistakes

Omitting RXV-1 because only one RXV is being sent. Set ID is required even on the first and only repetition.
Treating RXV-2 or RXV-7 as optional. They are ID-typed and required; sites must define a "no bolus" / "no PCA" sentinel value in their pump vocabulary.
Reporting a bolus or PCA dose amount (RXV-3, RXV-8) without its units (RXV-4, RXV-9). Receivers cannot assume mg, mcg, mL, or units-of-insulin.
Putting mg/h into RXV-16 as 30^mg/h when the pump's actual limit is per 4 hours. RXV-16 is CQ — the time window is part of the unit string.
Confusing RXV with RXR (route) or RXC (component). RXV is variance/PCA programming, not route or component.

Examples

Minimal RXV

RXV|1|NONE||||||NONE|||||||||30^mg/4h^UCUM

Fully-populated RXV

RXV|1|DEMAND^Patient-demand bolus^HL70835|1.0|mg^milligram^UCUM|1.0|mL^milliliter^UCUM|CONT^Continuous + demand^HL70836|0.2|mg^milligram^UCUM|0.2|mL^milliliter^UCUM|10|mg^milligram^UCUM|10|mL^milliliter^UCUM|30^mg/4h^UCUM|6^min^UCUM|BD^Becton Dickinson^L|PLASTIPAK-30ML^Plastipak 30 mL^L|30|mL^milliliter^UCUM|A

Annotated breakdown

RXV|1                       Set ID - RXV: first variance segment
   |DEMAND^...              Bolus Type: patient-demand bolus
   |1.0                     Bolus Dose Amount: 1.0
   |mg^...^UCUM             Bolus Dose Amount Units: mg
   |1.0                     Bolus Dose Volume: 1.0
   |mL^...^UCUM             Bolus Dose Volume Units: mL
   |CONT^...                PCA Type: continuous + demand
   |0.2                     PCA Dose Amount: 0.2
   |mg^...^UCUM             PCA Dose Amount Units: mg
   |0.2                     PCA Dose Volume: 0.2
   |mL^...^UCUM             PCA Dose Volume Units: mL
   |10                      Max Dose Amount: 10
   |mg^...^UCUM             Max Dose Amount Units: mg
   |10                      Max Dose Volume: 10
   |mL^...^UCUM             Max Dose Volume Units: mL
   |30^mg/4h^UCUM           Max Dose per Time: 30 mg per 4 hours (REQUIRED)
   |6^min^UCUM              Lockout Interval: 6 minutes between demands
   |BD^...                  Syringe Manufacturer
   |PLASTIPAK-30ML^...      Syringe Model Number
   |30                      Syringe Size: 30
   |mL^...^UCUM             Syringe Size Units
   |A                       Action Code: Add (variance posted)

In-context excerpt: RAS variance reporting

MSH|^~&|EMAR|TOWER-3W|PHARMSURV|HOSP|20260610142210||RAS^O17^RAS_O17|MSG00112877|P|2.8.1
PID|1||77231884^^^HOSP^MR||VANBUREN^IMOGEN^J||19610214|F
PV1|1|I|3W^312^A^HOSP||||74419^OBERLIN^HANNAH^^^DR|||MED||||||74419^OBERLIN^HANNAH^^^DR|INP|||||||||||||||||||||||20260609083000
ORC|RE|ORD-998812|FILL-554301|GRP-44871|||^Q6H^^20260609100000^20260615100000^R|||74419^OBERLIN^HANNAH^^^DR|||20260609095500
RXE|^Q6H^^20260609100000^20260615100000^R|MORPHINE-1MG-ML^Morphine sulfate 1 mg/mL inj^RXNORM|1|2|mg^milligram^UCUM|INJ^Injection^HL70162|||||1|mL^milliliter^UCUM
RXA|0|1|20260610142000||MORPHINE-1MG-ML^Morphine sulfate 1 mg/mL inj^RXNORM|2|mg^milligram^UCUM|||00^New admin^HL70322||TOWER-3W
RXV|1|DEMAND^Patient-demand bolus^HL70835|1.0|mg^milligram^UCUM|1.0|mL^milliliter^UCUM|CONT^Continuous + demand^HL70836|0.2|mg^milligram^UCUM|0.2|mL^milliliter^UCUM|10|mg^milligram^UCUM|10|mL^milliliter^UCUM|30^mg/4h^UCUM|6^min^UCUM|BD^Becton Dickinson^L|PLASTIPAK-30ML^Plastipak 30 mL^L|30|mL^milliliter^UCUM|A

In-context excerpt: max-dose lockout variance

MSH|^~&|SMARTPUMP|ICU-N4|PHARMSURV|HOSP|20260610181555||RAS^O17^RAS_O17|MSG00112991|P|2.8.1
PID|1||77231991^^^HOSP^MR||CALLISTER^EMRYS^P||19480930|M
PV1|1|I|N4^405^B^HOSP||||71902^MCKINLEY^ARJUN^^^DR|||CCU
ORC|RE|ORD-998917|FILL-554418|GRP-44993|||^CONT^^20260610170000^20260612170000^R|||71902^MCKINLEY^ARJUN^^^DR
RXE|^CONT^^20260610170000^20260612170000^R|HYDROMORPHONE-PCA^Hydromorphone PCA^RXNORM|0.2|mg^milligram^UCUM|IV^Intravenous^HL70162
RXA|0|1|20260610181500||HYDROMORPHONE-PCA^Hydromorphone PCA^RXNORM|0|mg^milligram^UCUM|||16^Refused^HL70322||ICU-N4
RXV|1|NONE^No clinician bolus^HL70835|||||DEMAND-ONLY^Demand only^HL70836|0.2|mg^milligram^UCUM|0.2|mL^milliliter^UCUM||||4|mg^milligram^UCUM|4|mL^milliliter^UCUM|4^mg/4h^UCUM|8^min^UCUM||||||LO

FHIR mapping

There is no segment-level ConceptMap published in the HL7 v2-to-FHIR Implementation Guide for RXV. In practice, integrators map RXV content to:

A MedicationAdministration variance (status = on-hold | not-done | stopped) when RXV-22 Action Code marks a lockout, refusal, or override.
MedicationAdministration.dosage extensions for PCA-specific parameters (RXV-3/4, RXV-8/9, RXV-16, RXV-17).
A DetectedIssue when RXV-16 Max Dose per Time was reached, with a reference back to the MedicationAdministration and the offending interval.
The pump itself as a Device, with RXV-18/19/20/21 captured as Device properties or DeviceMetric calibration data.

Because the IG does not normatively cover RXV, treat any local mapping as project-specific and document the choices in your interface specification.

Engine considerations

HAPI parses RXV with all 22 fields at v2.8.1. The ID-typed RXV-2/7/22 are not bound to a fixed value set in code; validate against your site's pump vocabulary in the application layer.
Mirth Connect / NextGen Connect typically passes RXV through to a clinical surveillance destination unchanged. Transformations are usually limited to normalizing units in RXV-4/6/9/11/13/15/21 to UCUM.
Cloverleaf / Rhapsody users often split RXV into a dedicated PCA-program record at the channel level so analytic platforms can query lockout intervals and max-dose limits without re-parsing HL7.
Iguana / Lyniate Iguana users frequently combine RXA + RXV into a single JSON administration event for downstream warehouses.
Trigger event handling: RAS/O17 in v2.8.1 carries one ORC, one RXE (or RXO+RXR), one RXA per administration event, and zero-or-more RXV per PCA program or variance. Engines should not drop RXV when RXA-20 Completion Status indicates "Refused" or "Not Administered" — the RXV is precisely what explains why.

How Vorro parses and produces RXV

The Vorro integration platform models RXV as a dosing-envelope record bound to the administration event asserted by the accompanying RXA. When parsing inbound RAS/O17 variance, Vorro:

Validates RXV-1 Set ID, RXV-2 Bolus Type, RXV-7 PCA Type, and RXV-16 Max Dose per Time as required and rejects the segment to a quarantine queue when any are missing.
Coerces every NM+CWE unit pair (RXV-3/4, RXV-5/6, RXV-8/9, RXV-10/11, RXV-12/13, RXV-14/15, RXV-20/21) into a {value, unit} object and validates the unit against UCUM, raising a soft warning when an unknown unit appears.
Parses RXV-16 Max Dose per Time and RXV-17 Lockout Interval into time-windowed limits and indexes them so surveillance queries can find every PCA program with >= 30 mg / 4h morphine equivalence in a single pass.
Promotes RXV-22 Action Code into a variance.action field on the administration record, preserving the original code for replay.

When producing RXV from pump telemetry, Vorro guarantees the required fields are populated, emits all units as UCUM, and refuses to emit a segment without the matching RXA so downstream systems always have administration context.

Sources

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