ISO 4135:2022

FINAL
INTERNATIONAL ISO/FDIS
DRAFT
STANDARD 4135
ISO/TC 121/SC 4
Anaesthetic and respiratory
Secretariat: ANSI
equipment — Vocabulary
Voting begins on:
2021­05­26
Anästhesie und Beatmungsgeräte — Begriffe
Voting terminates on:
Matériel d'anesthésie et de réanimation respiratoire — Vocabulaire
2021­07­21
ISO/CEN PARALLEL PROCESSING
RECIPIENTS OF THIS DRAFT ARE INVITED TO
SUBMIT, WITH THEIR COMMENTS, NOTIFICATION
OF ANY RELEVANT PATENT RIGHTS OF WHICH
THEY ARE AWARE AND TO PROVIDE SUPPOR TING
DOCUMENTATION.
IN ADDITION TO THEIR EVALUATION AS
Reference number ISO/FDIS
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO­
4135:2021(E/F/D)
LOGICAL, COMMERCIAL AND USER PURPOSES,
DRAFT INTERNATIONAL STANDARDS MAY ON
OCCASION HAVE TO BE CONSIDERED IN THE
LIGHT OF THEIR POTENTIAL TO BECOME STAN­
DARDS TO WHICH REFERENCE MAY BE MADE IN
©
NATIONAL REGULATIONS. ISO 2021

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ISO/FDIS 4135:2021(E/F/D)
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ISO/FDIS 4135:2021(E)

Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
3.1 General concepts . 1
3.1.1 Properties of gases and materials . 1
3.1.2 Properties of equipment . 5
3.1.3 Metrology concepts . 5
3.1.4 Equipment components . 8
3.1.5 Physiological terms . .14
3.1.6 Use environment and workflow .16
3.2 Medical gas supply systems .18
3.2.1 Pipeline systems .18
3.2.2 Terminal units .21
3.2.3 Low­pressure hose assemblies for use with medical gases.22
3.2.4 Pressure regulators .23
3.2.5 Gas cylinders and accessories .23
3.3 Anaesthetic machines and workstations .24
3.3.1 General terms .24
3.3.2 Components .25
3.4 Ventilators and resuscitators .26
3.4.1 General terms .26
3.4.2 Ports .28
3.4.3 Pressures .28
3.4.4 Flowrates .29
3.5 Oxygen therapy delivery systems .29
3.5.1 Liquid oxygen systems .29
3.6 Breathing systems .29
3.6.1 General terms and classification .29
3.6.2 Adaptors .31
3.6.3 Valves .31
3.7 Humidifiers, nebulizers and moisture exchangers .32
3.7.1 General terms .32
3.7.2 Humidifiers .32
3.7.3 Nebulizers .33
3.7.4 Heat and moisture exchangers .34
3.8 Airways, tracheal tubes, tracheostomy tubes and intubation equipment .35
3.8.1 General.35
3.8.2 Pharyngeal airway .35
3.8.3 Tracheal tubes .36
3.8.4 Bronchial tubes and blockers .37
3.8.5 Tracheostomy tubes .38
3.8.6 Masks and cannulae .38
3.8.7 Voice prostheses .39
3.8.8 Laryngoscopes .39
3.9 Anaesthetic gas scavenging and plume evacuation systems .40
3.9.1 General terms .40
3.10 Suction devices .43
3.10.1 General terms .43
3.10.2 Suction equipment .44
3.10.3 Suction catheters for the respiratory tract .45
3.11 Monitoring .45
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ISO/FDIS 4135:2021(E)

3.11.1 General terms .45
3.11.2 Gas monitors.46
3.11.3 Pulse oximeters .47
3.11.4 Thermometers .48
3.11.5 ECG equipment .48
3.11.6 Sphygmomanometers .51
3.11.7 Transcutaneous gas monitors .52
Annex A (informative) Terminology — Alphabetized index of defined terms .53
Bibliography .66
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ISO/FDIS 4135:2021(E)

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 non­governmental, 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).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction or on
the ISO list of patent declarations received (see www .iso .org/ patents).
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, in collaboration with the European Committee
for Standardization (CEN) Technical Committee CEN/TC 215, Respiratory and anaesthetic equipment, in
accordance with the Agreement on technical cooperation between ISO and CEN (Vienna Agreement).
This fourth edition cancels and replaces the third edition (ISO 4135:2001), which has been technically
revised.
The main changes compared to the previous edition are as follows:
— Deletion of terms that are no longer relevant to International Standards prepared by ISO/TC 121, or
that are defined in more widely applicable International Standards, such as ISO 14971.
— Deletion of terms that are specific to lung ventilators and that are covered in ISO 19223.
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.
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ISO/FDIS 4135:2021(E)

Introduction
In this document, the following print types are used:
— Definitions: roman type;
— Terms defined in this document or as noted: italic type;
— Informative material appearing outside of tables, such as notes, examples and references: in
smaller type.
The primary objective for this document has been to facilitate consistent use of terminology across all
the standards relevant to manufacturers, test laboratories and regulatory agencies with an interest in
equipment for use in anaesthesiology and respiratory care.
rd
Since the publication of the 3 edition of ISO 4135 in 2001, many new and updated standards have been
rd
published by ISO/TC 121. In many cases, terms defined in the 3 edition of ISO 4135 have not been
found sufficient for the purposes of these standards, resulting in terms being redefined in different
standards, or new terms created, such that users of the standards may be confused as to the meaning.
In preparation for this new edition, all the terms defined in ISO/TC 121 documents were reviewed. This
new edition is intended to address several objectives:
rd
a) Deletion of terms in the 3 edition of ISO 4135 that no longer fulfil a purpose, or that are now
included in ISO 19223;
b) Addition of terms from other ISO/TC121 standards where these can be of value across multiple
standards;
c) Encouragement of consistent use of terminology across ISO/TC 121 standards, in order to minimize
the potential for readers to misunderstand intent.
In preparation of this document it became apparent that many terms are defined in standards applicable
to medical equipment more widely than the scope of ISO/TC 121, and that redefining these terms in a
domain-specific terminology or in a product standard can lead to confusion when users of the standard
are familiar with the more generally applicable terminologies.
rd
A number of terms previously defined in the 3 edition of ISO 4135 or in other ISO/TC 121 standards,
particularly those for different categories of lung ventilators and anaesthetic workstations, are now
provided in ISO 19223:2019. These are freely available on the ISO online browsing platform (see Clause 3).
The ISO Online browsing platform is available at https:// www .iso .org/ obp
Terms defined in ISO 19223 have been included in this document where they have applicability outside
the scope of mechanical ventilation.
EXAMPLE 1 Airway pressure is included in this document because it has applicability in fields such as
pulmonary function testing.
EXAMPLE 2 Airway resistance is not included in this document because the only context of use of this term is
within standards for lung ventilators, for which ISO 19223 is an appropriate source.
Particular emphasis has been placed on the identification of instances where the same term is used for
different concepts, or where the same concept is identified by different terms.
This last point is particularly relevant for test laboratories, and for manufacturers using standards
from several different subcommittees of ISO/TC 121, or ISO/TC 121 standards alongside IEC/TC 62
standards. When multiple definitions exist, and particularly when terms in the general standard or
collaterals are redefined in particular standards, it is all too easy for the user of a standard to reference
the wrong definition, and hence misconstrue requirements.
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ISO/FDIS 4135:2021(E)

rd
In some cases terms were provided in different sections of the 3 edition of ISO 4135, with different
definitions. The Working Group amended the categorization and in some cases amended term names in
order to avoid any instances of terms with distinct definitions.
The terms, names and acronyms listed in this Standard have been described in a manner that formalizes
their interpretation to the extent that it minimizes ambiguity and provides a rigid usage discipline for
formal data handling and informatics, whilst retaining phraseology that is suitable for user instructions
and clinical dialog.
In the application of the vocabulary of this International Standard, the full term should always be used
wherever any ambiguity might arise from use of an abbreviated term and where there is no trade-
off with conciseness, for example, in the formulation of data bases. However, in many applications the
context of use may make some of the parts of a compound preferred term redundant, in which case
abbreviations, symbols and permitted terms may be used, as appropriate.
The vocabulary of this document is primarily arranged in a systematic order, with a secondary
alphabetical order. An alphabetical index of the terms defined in this document is provided in Annex A.
For terms that have different definitions in differing contexts, the definition context is specified in <>
before the definition.
This document is a “controlled vocabulary”, which includes “pre-coordinated terms”. It is expected
that users of this standard may also create “post-coordinated terms” by a process of concatenation
as appropriate to the field of use. Within the field of terminology standards, a pre-coordinated term
is a verbal designation of a concept with more than one root that can be split morphologically into
separate components and which is predefined in a controlled vocabulary, for example minute volume
and pressure-limiting valve, while a post-coordinated term is a verbal designation of a concept with
more than one root, created by a user by combining terms from controlled vocabularies. An example
of this would be supraglottic airway device, which can be created by combining the two individually
defined terms supraglottic and airway device.
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FINAL DRAFT INTERNATIONAL STANDARD ISO/FDIS 4135:2021(E)
Anaesthetic and respiratory equipment — Vocabulary and
semantics
1 Scope
This International Standard establishes a vocabulary of terms used for anaesthetic and respiratory
equipment and supplies, related devices and supply systems.
NOTE 1 This document is based on standards and drafts which have been produced by ISO/TC 121 and
CEN/TC 215.
NOTE 2 To avoid multiple definitions of the same term in different categories, this document attempts to
ensure consistency by the inclusion of a ‘general’ category, and by use of domain specifiers and unique pre-
coordinated domain-specific term names.
NOTE 3 In addition to terms and definitions used in two of the three official ISO languages (English and
French), this document gives the equivalent terms in the German language; these are published under the
responsibility of the member body for Germany. However, only the terms and definitions given in the official
languages can be considered as ISO terms and definitions.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
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
— IEC Electropedia: available at http:// www .electropedia .org/
3.1 General concepts
3.1.1 Properties of gases and materials
3.1.1.1
absolute humidity
mass of water vapour present in a unit volume of gas
Note 1 to entry: In respiratory applications absolute humidity is commonly represented in units of milligrams per
litre or grams per cubic metre, with volume expressed at BPTS condition.
Note 2 to entry: See also relative humidity (3.1.2.4).
3.1.1.2
adiabatic compression
compression process that occurs without transfer of heat into or out of a system
3.1.1.3
aerosol
suspension of liquid or solid particles in a gas
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ISO/FDIS 4135:2021(E)

3.1.1.4
air for driving surgical tools
natural or synthetic mixture of gases, mainly composed of oxygen and nitrogen in specified proportions,
with defined limits for the concentration of contaminants, and intended to act as a power source for
surgical tools
3.1.1.5
anaesthetic gas
gas, which may be the vapour of a volatile anaesthetic agent, or mixture of gases, used in anaesthesia
Note 1 to entry: In parts of an anaesthetic breathing system (3.6.1.8), anaesthetic gas includes gases exhaled by
the patient.
3.1.1.6
auto-ignition temperature
temperature at which a material will spontaneously ignite under specified conditions
3.1.1.7
body temperature and pressure saturated
BTPS
ambient atmospheric pressure, at a temperature of 37 °C, and at a relative humidity (3.1.2.4) of 100 %
3.1.1.8
standard temperature and pressure dry
STPD
pressure of 101,325 kPa at a temperature of 20 °C, dry
3.1.1.9
carrier gas
respirable gas that conveys a substance or substances to the patient
EXAMPLE Medical air (3.1.1.18) used to convey a bronchodilatory drug.
3.1.1.10
carrier gas
respirable gas that conveys one or more anaesthetic gases (3.1.1.5) to the patient
EXAMPLE Ambient air and oxygen (3.1.1.21) mixture in a draw-over vaporiser (3.3.2.3).
3.1.1.11
combustion
rapid oxidation to produce heat and light
3.1.1.12
compliance
change in volume of gas per unit pressure change within an enclosed space
Note 1 to entry: It is deprecated to include the measurement conditions into the definition of compliance; in
general compliance may be expressed at any specified measurement condition.
Note 2 to entry: to entry. ISO 19223 provides definitions for pulmonary compliance, respiratory system
compliance, static compliance and dynamic compliance, all of which relate to the patient. Various other standards
from ISO/TC 121 reference compliance with respect to items of equipment such as breathing tubes (3.1.4.4) and
reservoir bags.
3.1.1.13
delivered gas temperature
temperature of the gas, or aerosol (3.1.1.3) or both, being delivered to a patient, referenced to the
patient-connection port (3.1.4.41)
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ISO/FDIS 4135:2021(E)

3.1.1.14
delivered oxygen concentration
concentration of oxygen in the gas delivered at a specified location
EXAMPLE In a closed anaesthetic breathing system (3.6.1.8), 100 % oxygen can be added to the breathing
system (3.6.1.1) to match the patient’s oxygen consumption, with the respiratory gas monitor (3.11.2.1) at the
patient-connection port (3.1.4.41) measuring a much lower value for FiO2 (3.1.1.15).
3.1.1.15
FiO
2
fraction of inspired oxygen
concentration of oxygen in the gas inspired by a patient
Note 1 to entry: The measurement site for FiO should be specified by the equipment manufacturer but should be
2
referenced to the concentration of oxygen in the gas that is intended to be inspired.
EXAMPLE In a closed anaesthetic breathing system (3.6.1.8), 100 % oxygen can be added to the breathing
system (3.6.1.1) to match the patient’s oxygen consumption, with the respiratory gas monitor (3.11.2.1) at the
patient-connection port (3.1.4.41) measuring a much lower value for FiO .
2
3.1.1.16
fresh gas
respirable gas delivered to a breathing system (3.6.1.1)
Note 1 to entry: In a circle breathing system (3.6.1.8.1), the fresh gas is all respirable gas delivered into the circle
breathing system (including anaesthetic gases (3.1.1.5) and vapours). This can include oxygen (3.1.1.21) or air
delivered into a vaporiser, and it can also include the vapour generated by a vaporiser (3.3.2.2).
Note 2 to entry: In an open breathing system (3.6.1.1), the fresh gas is all respirable gas delivered into the breathing
system (which can be at any point within the breathing system).
3.1.1.17
gas for medicinal use
gas or mixture of gases that can be used either with a view to restore, correct or modify physiological
functions by exerting a pharmacological, immunological or metabolic action, or to make a medical
diagnosis
3.1.1.18
medical air
natural or synthetic mixture of gases, mainly composed of oxygen and nitrogen in specified proportions,
with defined limits for the concentration of contaminants, intended for administration to patients
3.1.1.19
medical device gas
gas or mixture of gases intended by the manufacturer to be used as a medical device or as an accessory
to a medical device
Note 1 to entry: This encompasses uses for investigation or modification of the anatomy or of a physiological
process, and which does not achieve its principal intended action by pharmacological, immunological or
metabolic means, in or on the human body, but which may be assisted in its function by such means.
Note 2 to entry: In some countries, medical device gases may be regulated as a medical device, a drug or not
subject to regulation.
EXAMPLE 1 EXAMPLES:
EXAMPLE 2 Liquid gases used for cryoablation.
EXAMPLE 3 Gases used to provide an anaerobic atmosphere.
EXAMPLE 4 Compressed air for hyperbaric chambers.
EXAMPLE 5 Driving gas for surgical tools.
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ISO/FDIS 4135:2021(E)

EXAMPLE 6 Inflating gases for laparoscopy.
3.1.1.20
medical gas
any gas or mixture of gases intended for administration to patients for anaesthetic, therapeutic,
diagnostic or prophylactic purposes, or as a source of pneumatic power for medical or surgical tools
3.1.1.21
oxygen
gas for medicinal use (3.1.1.17) where the oxygen concentration is at least the minimum specified in the
relevant pharmacopoeia monograph
3.1.1.22
oxygen 93
DEPRECATED: oxygen-enriched air
gas for medicinal use (3.1.1.17) where the oxygen
...