prEN ISO 19223-1

SLOVENSKI STANDARD
01-oktober-2026
Pljučni ventilatorji in pripadajoča oprema - Slovar in semantika - 1. del: Pljučni
ventilatorji (ISO/DIS 19223-1:2026)
Lung ventilators and related equipment - Vocabulary and semantics - Part 1: Lung
ventilators (ISO/DIS 19223-1:2026)
Beatmungsgeräte und zugehörige Geräte - Terminologie und Semantik - Teil 1:
Beatmungsgeräte (ISO/DIS 19223-1:2026)
Ventilateurs pulmonaires et équipement associé - Vocabulaire et sémantique - Partie 1:
Ventilateurs pulmonaires (ISO/DIS 19223-1:2026)
Ta slovenski standard je istoveten z: prEN ISO 19223-1
ICS:
01.040.11 Zdravstveno varstvo Health care technology
(Slovarji) (Vocabularies)
11.040.10 Anestezijska, respiratorna in Anaesthetic, respiratory and
reanimacijska oprema reanimation equipment
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

DRAFT
International
Standard
ISO/DIS 19223-1
ISO/TC 121/SC 4
Lung ventilators and related
Secretariat: ANSI
equipment — Vocabulary and
Voting begins on:
semantics —
2026-08-04
Part 1:
Voting terminates on:
2026-10-27
Lung ventilators
ICS: 11.040.10; 01.040.11
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENTS AND APPROVAL. IT
IS THEREFORE SUBJECT TO CHANGE
AND MAY NOT BE REFERRED TO AS AN
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PUBLISHED AS SUCH.
This document has not been edited by the ISO Central Secretariat.
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Reference number
ISO/DIS 19223-1:2026(en)
DRAFT
ISO/DIS 19223-1:2026(en)
International
Standard
ISO/DIS 19223-1
ISO/TC 121/SC 4
Lung ventilators and related
Secretariat: ANSI
equipment — Vocabulary and
Voting begins on:
semantics —
Part 1:
Voting terminates on:
Lung ventilators
ICS: 11.040.10; 01.040.11
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENTS AND APPROVAL. IT
IS THEREFORE SUBJECT TO CHANGE
AND MAY NOT BE REFERRED TO AS AN
INTERNATIONAL STANDARD UNTIL
PUBLISHED AS SUCH.
This document has not been edited by the ISO Central Secretariat.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL,
© ISO 2026
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
STANDARDS MAY ON OCCASION HAVE TO
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Published in Switzerland Reference number
ISO/DIS 19223-1:2026(en)
ii
ISO/DIS 19223-1:2026(en)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms,definitions, symbols, and abbreviated terms . 1
3.1 General artificial-ventilation terminology .2
3.1.1 Referenced terms .2
3.1.2 Qualifiers defined in this document .3
3.1.3 Ventilation equipment terms . .5
3.1.4 Respiratory mechanics .7
3.1.5 Ventilation classes .11
3.2 Breath terminology . 13
3.3 Ventilation control paradigms . .17
3.4 Lung inflation terminology .18
3.4.1 Inflation classification terminology .18
3.4.2 Inflation control terms .19
3.4.3 Inflation pattern terms . . . 23
3.5 Phase and cycle terminology .24
3.6 Time measurement terminology .27
3.7 Rate terminology . 30
3.8 Pressure terminology . .32
3.9 Flow terminology . 36
3.10 Volume terminology . 39
3.10.1 Breath and inflation volume terms . 39
3.10.2 Minute ventilation terms . 40
3.11 Initiation and termination terminology .43
3.12 Baseline and PEEP terminology . 46
3.13 Mode terminology. 50
3.13.1 General mode terminology . 50
3.13.2 Ventilation mode classification .52
3.13.3 Ventilation mode names . 56
3.13.4 Fail-safe and apneoa ventilation .62
3.14 Bi-level terminology . . . 63
3.15 Safety limits and alarm terminology . 68
Annex A (informative) Illustrations of ventilation terms .71
Annex B (informative) Concepts relating to baseline airway pressures and PEEP as used in this
document .108
Annex C (informative) Systematic Coding for Health Informatics and Medical Device
Communications.117
Annex D (informative) Implementation of this terminology in ventilator labelling and
instructions .125
Annex E (informative) Terminology — Alphabetized index of defined terms . 128
Bibliography .135

iii
ISO/DIS 19223-1:2026(en)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out through
ISO technical committees. Each member body interested in a subject for which a technical committee
has been established has the right to be represented on that committee. International organizations,
governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely
with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types
of ISO documents should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions
related to conformity assessment, as well as information about ISO's adherence to the World Trade
Organization (WTO) principles in the Technical Barriers to Trade (TBT) see www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 121, Anaesthetic and respiratory equipment,
Subcommittee SC 4, Vocabulary and semantics.
A list of all parts in the ISO 19223 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.

iv
ISO/DIS 19223-1:2026(en)
Introduction
The characteristics of ventilation-modes of current automatic lung ventilators are complex and often not well
understood. Some ventilator manufacturers have created proprietary terms to describe ways of ventilating
patients, and other manufacturers have used existing terms with different meanings in different situations.
This has led to patient safety hazards, an example being that lung ventilator clinical orders (settings) for
one model of ventilator can be quite different from those required to get the same result from a different
ventilator. International standards are necessary to prevent inconsistencies that may result in risks to
patients. This document provides standardized terminology and semantics for artificial ventilation. Where
possible, terms already in general use have been incorporated, while clearly defining each term and limiting
its potential for misuse. New terms and deprecation of previous terms have been necessary to ensure a clear
understanding of the interactions between the patient and the ventilator.
This document has been developed with the participation, cooperation and assistance of clinicians, members
of other standards development organizations, and major international ventilator manufacturers. The
applications include lung ventilators, anaesthesia and respiratory therapy equipment, health informatics
systems facilitating clinical care, research, interoperability, incident reporting and equipment maintenance.
Ventilators have become increasingly interactive with the patient, and terminology must take this into
account.
The terminology in this document is defined to facilitate both the setting of a ventilator and how to describe
and record the resultant ventilator-patient interactions, continuously and at defined points within the
course of ventilation. This includes the result of the complex interactions that occur when additional breaths
are taken during an assured-inflation cycle, as can occur, for example, during APRV (airway pressure release
ventilation).
Ventilation-modes of modern ventilators require the selection of both the pattern that determines when and
what inflations occur, and the method used to inflate the lungs; functions that can be conveniently referred
to as the ventilation-pattern and the inflation-type. In most cases the choice of inflation-type is largely
independent of the choice of ventilation-pattern.
In this document, the ventilation-mode is a composite of these two independent, user-selectable elements:
the ventilation-pattern determines how the ventilator will respond to patient-trigger events and what it will
cause to be delivered, when, irrespective of the patient’s respiratory activity and the inflation-type which
determines how the pressure or flow at the patient-connection port will be regulated during an inflation,
once initiated.
This format, with its focus on the pattern to which inflations are initiated and on the type of inflation that
is delivered, is independent of which ventilation-pattern and inflation-type combination can be used with
which setting, and for which clinical intention. Its structure not only reduces the number of items to be
remembered but also makes them much easier to teach, learn, remember and recognize, thereby improving
ventilator usability. The overall objective is to encourage a consistent use of ventilator vocabulary so that
users trained in the application of this document will be able to move easily from one ventilator to another
and operate each one, with confidence, after a minimum amount of training.
Some of the terms in this document are principally intended for technical documents, informatics and
related applications (see Annex C) and might have little applicability to ventilator labelling and instructions
for use (see Annex D).
The notes to some definitions refer to post-coordinated terms. These are terms formed by the combination
of two defined terms, or of a defined term with a natural language word, to form a new compound term.
Usually, the additional term or word qualifies the base term by reference to an alternative site, pressure
level or point of occurrence within a respiratory cycle. It can place a restriction on the applicability of the
base term.
Examples of the application of this document are illustrated in the figures of Annex A and Annex B but
these are not intended to indicate a requirement, nor to impose any restriction on the design of artificial

v
ISO/DIS 19223-1:2026(en)
ventilation devices. Colour coding is employed in most of these figures of this document to help distinguish
between some of the specific characteristics being illustrated.
[1]
NOTE The following figures have been adapted from Reference with permission:
— Figures: Figure A.1 to Figure A.35 and Figure B.1 to Figure B.7.

vi
DRAFT International Standard ISO/DIS 19223-1:2026(en)
Lung ventilators and related equipment — Vocabulary and
semantics —
Part 1:
Lung ventilators
1 Scope
This document defines terms for fields of respiratory care involving artificial ventilation, such as intensive-
care ventilation, anaesthesia ventilation, emergency and transport ventilation and home-care ventilation.
This document is applicable:
— in lung ventilator and breathing-therapy equipment device standards,
— in health informatics standards,
— for labelling on medical electrical equipment and medical electrical systems,
— in medical electrical equipment and medical electrical system instructions for use and accompanying
information,
— for medical electrical equipment and medical electrical systems interoperability, and
— in electronic health records.
This document is also applicable to those accessories intended by their manufacturer to be connected to a
ventilator breathing system or to a ventilator, where the characteristics of those accessories can affect the
basic safety or essential performance of the ventilator and ventilator breathing system.
NOTE This document can also be used for other applications relating to lung ventilation, including non-electrical
devices and equipment, research, description of critical events, forensic analysis and adverse event (vigilance)
reporting systems.
This document does not specify terms specific to high-frequency ventilation or jet ventilation, which
[2]
are defined in ISO 19223-2:2025 , terms specific to breathing-therapy equipment, which are defined
[3]
in ISO 19223-3:2025 , or to physiologic closed-loop ventilation, negative-pressure ventilation; nor to
respiratory support using liquid ventilation or extra-corporeal gas exchange, or oxygen, except where it has
been considered necessary to establish boundaries between bordering concepts.
[4]
This document is structured based on the guidance and requirements specified in ISO 704:2022 and
[5]
ISO 10241-1:2011 .
2 Normative references
There are no normative references in this document.
3 Terms,definitions, symbols, and abbreviated terms
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp

ISO/DIS 19223-1:2026(en)
— IEC Electropedia: available at http:// www .electropedia .org/
NOTE For convenience, an index and a list of sources of all defined terms used in this document are provided in
Annex E.
3.1 General artificial-ventilation terminology
3.1.1 Referenced terms
3.1.1.1
normal use
operation, including standby, routine inspection and adjustments by any user, in accordance with the
accompanying information (3.1.1.6) or, for those medical devices provided without accompanying information
(3.1.1.6), with generally accepted practice
Note 1 to entry: Normal use should not be confused with intended use (3.1.1.2). While both include the concept of use
as intended by the manufacturer, intended use (3.1.1.2) focuses on the medical purpose while normal use incorporates
not only the medical purpose, but also matters such as maintenance, transport.
[6]
[SOURCE: IEC 60050-880 , 880-21-07]
3.1.1.2
intended use
intended purpose
use for which a product or process is intended according to the specifications, instructions for use and other
accompanying information (3.1.1.6)
[6]
[SOURCE: IEC 60050-880 , 880-21-06]
Note 1 to entry: Intended use should not be confused with normal use (3.1.1.1). While both include the concept of use
as intended by the manufacturer, intended use focuses on the medical purpose while normal use (3.1.1.1) incorporates
not only the medical purpose, but also such matters as maintenance, service and transport.
3.1.1.3
normal condition
condition of a medical device or accessory in which all risk control measures are intact
[6]
[SOURCE: IEC 60050-880 , 880-18-11]
3.1.1.4
single fault condition
condition of a medical device or accessory in which a single risk control measure is defective
[6]
[SOURCE: IEC 60050-880 , 880-18-25.]
3.1.1.5
protection device
part or function of a medical device that, without intervention by the user, protects against a hazard or a
hazardous output
[6]
[SOURCE: IEC 60050-880 , 880-16-08.]
3.1.1.6
accompanying information
DEPRECATED: accompanying document
information supplied by the manufacturer with or marked on a medical device or accessory for the user or the
responsible organization, particularly regarding safe use
[6]
[SOURCE: IEC 60050-880 , 880-11-01.]

ISO/DIS 19223-1:2026(en)
3.1.1.7
port
fluid port
opening for the passage of a fluid through a specified interface
Note 1 to entry: Typical interfaces where ports occur are:
— where breathing gas enters a ventilator,
— where water for humidification enters a humidifier,
— where operator-detachable tubing is connected to a medical device, and
— where a VBS (3.1.3.4) is connected to the patient or to an airway device (3.1.3.3).
Note 2 to entry: A port can be in the form of a specific connector or be designed to not allow connection with any
connector.
[6]
[SOURCE: IEC 60050-880 , 880-05-02. Modified - added preferred term port]
3.1.2 Qualifiers defined in this document
3.1.2.1
set
setting
allocated a specific value
EXAMPLE 1 A set pressure limit (3.1.2.5).
EXAMPLE 2 The set Δ inspiratory pressure (3.8.6).
Note 1 to entry: Set is used in this document as a prefix to distinguish an intended value for a controlled artificial
ventilation (3.1.5.2) variable from a measured (3.1.2.2) or actual value (3.1.2.4) of the same quantity, if this is not
evident from the context of use.
Note 2 to entry: A set value might be determined directly by the user or indirectly by selection of an algorithm that
determines the setting based on other set or measured (3.1.2.2) values.
Note 3 to entry: See also the references to settings in Annex A and Annex C.
3.1.2.2
measured
determined by a measuring device or system
Note 1 to entry: This term is used in this document as a prefix to distinguish the value of a quantity as determined by
a measuring device or system, from an actual value (3.1.2.4) or set (3.1.2.1) value of the same quantity, if this is not
evident from the context of use.
Note 2 to entry: Measured values might be displayed or recorded as discrete values or as a continuous waveform.
3.1.2.3
preset
one of a set of stored configuration parameter(s), including selection of algorithms and initial values for use
by algorithms, which affects or modifies the performance of the ventilator (3.1.3.1)
Note 1 to entry: Presets are commonly configured by the manufacturer or a responsible organization.
Note 2 to entry: Access to a preset value is typically controlled by
— a tool,
— a responsible-organization password and a technical description, separate from the instructions for use,
— an individual user password,

ISO/DIS 19223-1:2026(en)
— voice recognition, or
— biometric means.
3.1.2.4
actual value
value of a quantity as it exists in fact
Note 1 to entry: This is the true value of a quantity, which might, or might not, be determinable by a measuring device.
Note 2 to entry: The definitions of terms denoting quantities, in this document, denote the actual value of that
quantity. Set (3.1.2.1) values are the means by which an user informs the ventilator (3.1.3.1) of the intended actual
value, and measured (3.1.2.2) values are displays or records of the actual value, to the accuracy and resolution of the
measuring system.
3.1.2.5
limit
point or level beyond which the value of a parameter cannot pass without an action by the ventilator (3.1.3.1)
Note 1 to entry: The action might be a notification or the implementation of means to prevent or mitigate a hazardous
situation.
Note 2 to entry: In this document, this term is restricted to the designation of safety constraints that provide patient
protection that is completely independent of the controlled ventilation (3.1.5.1) parameters.
Note 3 to entry: An alarm system uses an alarm limit in determining an alarm condition.
Note 4 to entry: See also Annex E and safety limits and alarm terminology (3.15).
3.1.2.6
initiate
cause a process or action to begin
Note 1 to entry: This word has been adopted in this document as the general term to designate the concept of causing
a process or action to begin. This is to counter a tendency to use the word trigger (3.11.1) for this purpose; a trend that
removes the ability of that term to differentiate its own special meaning from that of a simple timed switching action.
In this document, an inflation (3.4.1.1) can be initiated by, for example:
— a patient-trigger event (3.11.5);
— a timed signal;
— a manual input;
— a conditional termination (3.11.12) of an expiratory phase (3.5.6);
— a signal from a remote device.
Note 2 to entry: In this document, an inflation (3.4.1.1) that is initiated by a timed signal may be referred to as being
ventilator-initiation (3.11.9).
Note 3 to entry: A conditional termination (3.11.12) of an expiratory phase (3.5.6) is typically achieved by establishing
an expiratory flow (3.9.5) threshold at which the next inflation (3.4.1.1) is initiated. An initiation of this type is
sometimes used, for example, to optimize the expiratory time (3.6.6) in an APRV (3.13.3.9) mode. Such a threshold flow
is typically expressed as either a set (3.1.2.1) expiratory flow (3.9.5) or a set (3.1.2.1) percentage of the peak expiratory
flow (3.9.5).
ISO/DIS 19223-1:2026(en)
3.1.2.7
mandatory
required to occur
Note 1 to entry: This term is defined as used in this document, with a specific meaning of the word mandatory, which
in natural language has a spectrum of meanings. It has become firmly established in the vocabulary of artificial
ventilation (3.1.5.2) but, because of its ambiguity, it can denote either ‘total control’ or, as in this definition, ‘required
to occur’. In early artificial ventilation (3.1.5.2) practice, it was usual for all aspects of the patient's ventilation (3.1.5.1)
to be taken over by the ventilator (3.1.3.1) and so every breath (3.2.1) could be described as mandatory in its broadest
sense. Since then, with the introduction of breath synchronization (3.11.6) and the concept of support for spontaneous
breaths (3.2.3), only a small percentage of patients currently have their ventilation (3.1.5.1) totally controlled. However,
there remains a mandatory component to all forms of artificial ventilation (3.1.5.2) but a key aspect for an user when
setting a contemporary ventilator (3.1.3.1) is being assured that, when a selected inflation-type (3.4.1.2) is delivered
within the selected ventilation-pattern (3.13.1.3), it will provide at least a minimum level of assistance and, in the case
of apnoea, that the ventilation (3.1.5.1) will be totally controlled.
These developments have led manufacturers to increasingly restrict the use of the term ‘mandatory’ to the context
of ventilation (3.1.5.1) that is assured to occur by the programmed delivery of a selected inflation-type (3.4.1.2), in
predetermined patterns, at a rate that is independent of the patient's respiratory activity (3.2.6). This is the only sense
in which the term mandatory is used in this document; which is mainly in the explanation of the classical mode names
such as continuous mandatory ventilation (3.13.3.2), intermittent mandatory ventilation (3.13.3.4) and synchronized
intermittent mandatory ventilation (3.13.3.5). For other purposes, wherever possible, the word assured is used in its
place.
3.1.2.8
rise time
indication of the time for the regulated parameter to rise to a set (3.1.2.1) value following the initiation
(3.1.2.6) of an inflation (3.4.1.1)
Note 1 to entry: The rise time is often expressed as the slope of a ramp or as the time-constant of the rise although
neither of these terms depicts the actual typical trajectory of this pressure rise precisely.
Note 2 to entry: For pressure-regulation (3.3.2), this is the time to reach a set (3.1.2.1) inspiratory pressure (3.8.2), for
flow-regulation (3.3.1) it is the time to reach a set (3.1.2.1) inspiratory flow (3.9.2).
Note 3 to entry: See also Figure A.1 and Figure A.9 to Figure A.13.
3.1.2.9
Δ
delta
difference between two quantities
Note 1 to entry: This symbol is used in this document as a prefix to denote that the qualified parameter is referenced
to another parameter. In particular, it is used in this document to qualify an inspiratory pressure (3.8.2) or expiratory
pressure (3.8.8) to denote when it is referenced to a baseline airway pressure (3.12.1) level instead of to the default,
ambient pressure level.
Note 2 to entry: In verbal communication, Δ, as used in this document, is expressed as either ‘delta’ or ‘differential’.
Note 3 to entry: See also Figure A.1, Figure A.9, Figure A.10, Figure A.29, Figure A.30 and Figure A.33.
3.1.3 Ventilation equipment terms
3.1.3.1
ventilator
lung ventilator
DEPRECATED: respirator
medical device or medical electrical equipment intended to provide artificial ventilation (3.1.5.2)
Note 1 to entry: In cases of possible ambiguity the full term, lung ventilator, should be used.

ISO/DIS 19223-1:2026(en)
3.1.3.2
airway
patient airway
connected, gas-containing cavities and passages within the respiratory system (3.1.4.2), that conduct gas
between the alveoli and the oral and nasal orifices on the surface of the face, or the patient-connection port
(3.1.3.9) if an airway device (3.1.3.3) is used
Note 1 to entry: This is a well-established term that is commonly used in isolation in references to the airway of a
patient. Depending on the context, it is sometimes more helpful to use the admitted term patient airway.
3.1.3.3
airway device
device intended for use as an interface between the patient-connection port (3.1.3.9) of a ventilator (3.1.3.1)
and the patient's airway (3.1.3.2), and which has no auxiliary features on which the ventilator (3.1.3.1) is
dependent for its normal operation
EXAMPLE Endotracheal tube; tracheotomy tube; face mask; supralaryngeal airway.
Note 1 to entry: The connection to the patient's airway (3.1.3.2) can be at the face (non-invasive) or internal to the
patient (invasive).
Note 2 to entry: A face mask that intentionally vents respiratory gas to atmosphere by means of a bleed orifice is a
functional part of the ventilator breathing system (3.1.3.4) and therefore not an airway device. With that arrangement,
the face seal of the mask becomes the patient-connection port (3.1.3.9) and there is no patient-connection port (3.1.3.9)
connector, nor an airway device.
3.1.3.4
VBS
ventilator breathing system
anaesthesia breathing system
pathways through which gas flows to or from the patient at respiratory pressures, bounded by the port
(3.1.1.7) through which respirable gas enters, the patient-connection port (3.1.3.9) and the gas exhaust port
(3.1.3.6)
Note 1 to entry: These pathways typically extend within and outside the body of the ventilator (3.1.3.1), with those
outside being user-detachable.
Note 2 to entry: The port (3.1.1.7) of entry of a respirable gas into the ventilator breathing system can be inside
the body of the ventilator (3.1.3.1) and should not be confused with an external connection port (3.1.1.7) into which
respirable gas enters before being reduced to respirable pressures.
Note 3 to entry: The admitted term is included in this document for use in reference to the specific class of ventilator
(3.1.3.1) that are configured to ventilate patients with an anaesthetic gas mixture. With this application, the ‘respirable
gas’ is ‘anaesthetic gases' and the 'port (3.1.1.7) through which respirable gas enters’ can be referred to as the ‘fresh-
gas inlet’.
3.1.3.5
sleep-apnoea breathing-therapy equipment
medical equipment intended to alleviate the symptoms of a patient who suffers from sleep apnoea by
delivering a therapeutic baseline airway pressure (3.12.1) to the patient
Note 1 to entry: Sleep-apnoea breathing-therapy equipment is primarily used in the home healthcare environment
by a lay user without direct professional supervision.
3.1.3.6
exhaust port
port (3.1.1.7) of the medical equipment or device from which gas is discharged to the atmosphere during
normal use (3.1.1.1), either directly or via an anaesthetic gas scavenging system
3.1.3.7
gas output port
port (3.1.1.7) of the ventilator (3.1.3.1) through which gas is delivered at respiratory pressures to an user-
detachable part of the VBS (3.1.3.4)

ISO/DIS 19223-1:2026(en)
3.1.3.8
gas return port
port (3.1.1.7) of the ventilator (3.1.3.1) through which gas is returned at respiratory pressures through an
user-detachable part of the VBS (3.1.3.4) from the patient-connection port (3.1.3.9)
3.1.3.9
patient-connection port
port (3.1.1.7) of a VBS (3.1.3.4) intended for connection to an airway device (3.1.3.3)
Note 1 to entry: The patient-connection port is the end of the ventilator breathing system (3.1.3.4) proximal to the
patient.
Note 2 to entry: The patient-connection port is typically in the form of a suitable for connection to an airway device
(3.1.3.3) such as a tracheal or tracheostomy tube, a face mask, or a supralaryngeal airway, or to a test apparatus.
Note 3 to entry: Current particular standards typically specify that the patient-connection port is required to be in
the form of a specific standardized connector(s), for example, a connector(s) conforming to ISO 5356-1.
Note 4 to entry: In ventilators (3.1.3.1) designed to provide NIV (3.1.5.7) and where the artificial ventilation (3.1.5.2)
function is dependent upon a design feature of a component that connects the ventilator (3.1.3.1) to the patient's airway
(3.1.3.2), then the patient-connection port typically becomes the contact line of the seal to the patient's face and there
is no patient-connection-port connector.
3.1.3.10
fraction of inspired oxygen
FiO
concentration of oxygen in the breathing gas provided to a patient
Note 1 to entry: The fraction of inspired oxygen is conventionally measured and expressed as a volume fraction in the
dry breathing gas mixture, prior to any humidification of the breathing gas.
Note 2 to entry: The fraction of inspired oxygen is reported either as a fraction (in the range 0.21 to 1.00) or as a
percentage value.
3.1.3.11
heliox
breathing gas mixture comprising oxygen and helium
Note 1 to entry: Heliox with a fraction of inspired oxygen (3.1.3.10) in the range 0.20 to 0.40, and with the balance being
helium, is used in some cases of restricted airway disease as the lower density of helium compared with nitrogen
results in more laminar flow, and consequent reduction in airway resistance (3.1.4.3).
3.1.4 Respiratory mechanics
3.1.4.1
lung
each of the pair of compliant organs within the ribcage (thorax), bounded by the terminal bronchiole and the
visceral pleura, which during ventilation (3.1.5.1) provide gas/blood interfaces that enable oxygen from the
gas to pass into the blood and carbon dioxide to be removed
Note 1 to entry: In accordance with what has become common practice in the absence of a more suitable term, this
term in its singular form is also used in this document to reference the connected, respiratory-gas containing cavities
within the respiratory system (3.1.4.2), consisting of the airway (3.1.3.2) and the lungs. Examples of this common
practice in applications that are outside the scope of this document are: lung function; lung disease; lung compliance;
lung mechanics; test lung. Other established examples are lung ventilator; lung elastance; lung protective strategy.
Note 2 to entry: Although there are no such references in this document, if in the application of this document a need
arises to refer to just one of the lungs then, in order to avoid any possible ambiguity, it should always be identified as
such, or as the left lung or right lung.

ISO/DIS 19223-1:2026(en)
3.1.4.2
respiratory system
anatomical system related to breathing (3.2.2) including the airway (3.1.3.2), lungs (3.1.4.1), chest wall,
pleural space, brainstem respiratory control centre, phrenic nerves, neuromuscular junctions, diaphragm
and accessory muscles of ventilation (3.1.5.1)
3.1.4.3
airway resistance
drop in pressure between the patient-connection port (3.1.3.9) and the alveoli per unit rate of airway (3.1.3.2)
flow
Note 1 to entry: The airway resistance is normally expressed as a single coefficient, with the implicit assumptions
that it is independent of the flow rate and of the direction of flow. In practice, these assumptions are typically only
approximately valid.
Note 2 to entry: Test equipment that simulates airway resistance commonly provides either a linear resistance to flow,
representing fully laminar fluid dynamics, or a parabolic resistance to flow, representing turbulent fluid dynamics.
Note 3 to entry: The airway resistance can differ between the inspiratory phases (3.5.2) and expiratory phases (3.5.6).
3.1.4.4
respiratory compliance
C
rs
respiratory system compliance
DEPRECATED: lung compliance
elastic characteristic of the lung (3.1.4.1) expressed as the change in lung (3.1.4.1) volume per unit change of
airway pressure (3.8.1) in the absence of respiratory activity (3.2.6)
Note 1 to entry: The respiratory system compliance is normally expressed as a single coefficient, with the implicit
assumptions that it is independent of the volume of gas in the lung (3.1.4.1) and of any hysteresis between increasing
and decreasing volumes. In practice, these assumptions are typically only approximately valid.
Note 2 to entry: In mechanical ventilation (3.1.5.3) respiratory system compliance is determined as either a static
compliance (3.1.4.7) or a dynamic compliance (3.1.4.8). There might be differences between the values obtained by
these different methods, not only due to the method itself but also due to viscoelastic effects, pressure balancing
throughout the slower compartments of the lungs (3.1.4.1) and possible recruitment effects. Any measured value
needs to be identified using the method of measurement (C , C ).
rs,stat rs,dyn
Note 3 to entry: It is sometimes more applicable to express this characteristic as elastance, which is simply the inverse
of respiratory system compliance.
3.1.4.5
pulmonary compliance
C
L
elastic characteristic of the lungs (3.1.4.1) expressed as the change in the lung (3.1.4.1) volume per unit
change of the difference between the alveolar pressure and the pressure in the pleural space
Note 1 to entry: The pulmonary compliance is the compliance coefficient relating specifically to the lungs (3.1.4.1),
as distinct from the respiratory system compliance (3.1.4.4) which relates to the whole of the respiratory system
(3.1.4.2) and, therefore, includes the compliance of the thoracic cage. For most patients it is not clinically necessary
to differentiate between the compliance of the lungs (3.1.4.1) alone, and the compliance of the respiratory system
(3.1.4.2), so the more directly measurable respiratory system compliance (3.1.4.4) provides sufficient information. If an
impaired respiratory system (3.1.4.2) is indicated, the difference might be significant and can justify the more invasive
and skilled procedure required to obtain a measurement of pressure in the pleural space (the intrapleural pressure)
and, thereby, that of the pulmonary compliance.
Note 2 to entry: The difference between the alveolar pressure and the pleural pressure is typically referred to as the
transpulmonary pressure.
Note 3 to entry: The pulmonary compliance is normally expressed as a single coefficient, with the implicit assumptions
that it is independent of the volume of gas in the lungs (3.1.4.1), of any hysteresis between increasing and decreasing
volumes and of any variation of the pleural pressure withi
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