National foreword

This British Standard is the UK implementation of EN ISO 20789:2019. It is identical to ISO 20789:2018. It supersedes BS ISO 20789:2018, which is withdrawn

The UK participation in its preparation was entrusted to Technical Committee CH/121, Anaesthetic and respiratory equipment.

A list of organizations represented on this committee can be obtained on request to its secretary.

BSI, as a member of CEN, is obliged to publish EN ISO 20789:2019 as a British Standard. However, attention is drawn to the fact that during the development of this European Standard, the UK committee voted against its approval.

The UK committee submitted a negative vote as it is the opinion of the UK committee that passive humidifiers do not provide any clinically significant humidification to patients. This has been exacerbated in this latest version as the minimum performance requirement has been replaced by a manufacturer's declaration.

This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application.

Compliance with a British Standard cannot confer immunity from legal obligations.

This British Standard was published under the authority of the Standards Policy and Strategy Committee on 31 July 2018.

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. 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 and/or on the ISO list of patent declarations received. 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 on 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 WTO principles in the Technical Barriers to Trade (TBT) see the following URL: Foreword - Supplementary information

This document was prepared by Technical Committee ISO/TC 121, Anaesthetic and respiratory equipment, Subcommittee SC 3, Lung ventilators and related equipment.

Introduction

This document specifies requirements for so called “cold bubble-through or cold pass-over” respiratory tract passive humidifiers intended for use on patients in home care and in healthcare facilities. Passive humidifiers are used to raise the water content of gases delivered to patients. Gases available for medical use do not contain sufficient moisture and can damage or irritate the respiratory tract or desiccate secretions of patients whose upper airways have been bypassed. Inadequate humidity at the patient-connection port can cause drying of the upper airway, or desiccation of tracheo-bronchial secretions in the tracheal or tracheostomy tube, which can cause narrowing or even obstruction of the airway^[¹^][²^]1.

Passive humidifiers rely on moisture being transferred from a liquid reservoir to the gas at room temperature, without heating of either the humidification chamber or breathing tubes, to increase the water content of gases delivered to patients. Hence, such respiratory tract passive humidifiers have a lower mg/l output than active humidifiers. Refer to ISO 80601‑2‑74 for basic safety and essential performance of active humidifiers.

Since the safe use of a passive humidifier depends on the interaction of the passive humidifier with its accessories, this document sets total system performance requirements up to the patient-connection port. These requirements are applicable to accessories such as breathing tubes.

This document also constitutes a major technical revision of a portion of ISO 8185:2007^[³^], which it replaces in combination with ISO 80601‑2‑74. The most significant changes relative to ISO 8185:2007 for passive humidifiers are the following modifications:

extending the scope to include the passive humidifier and its accessories, where the characteristics of those accessories can affect the basic safety or essential performance of the passive humidifier, and thus not only the passive humidifier itself;
modification of the humidification test procedure and the disclosure of humidification performance;

and the following additions:

requirements for mechanical strength (via IEC 60601‑1‑11);
new symbols;
requirements for a passive humidifier as a component of a system;
requirements for cleaning and disinfection procedures;
requirements for biocompatibility;
requirements for fire prevention;
requirements for usability.

Passive humidifiers are commonly used with air and air-oxygen mixtures and a passive humidifier should be able to operate with these gases. Care should be taken if using other gas mixtures such as helium/oxygen mixtures as their physical properties are different from those of air and oxygen.

In this document, the following print types are used:

requirements and definitions: roman type;
test specifications: italic type;
informative material appearing outside of tables, such as notes, examples and references: in smaller type. Normative text of tables is also in a smaller type;
terms defined in Clause 3 of this document or as noted: small capitals.

In this document, the conjunctive “or” is used as an “inclusive or” so a statement is true if any combination of the conditions is true.

The verbal forms used in this document conform to usage described in Annex H of the ISO/IEC Directives, Part 2. For the purposes of this document, the auxiliary verb:

“shall” means that compliance with a requirement or a test is mandatory for compliance with this document;
“should” means that compliance with a requirement or a test is recommended but is not mandatory for compliance with this document;
“may” is used to describe a permissible way to achieve compliance with a requirement or test.

An asterisk (*) as the first character of a title or at the beginning of a paragraph or table title indicates that there is guidance or rationale related to that item in Annex A.

This European Standard was approved by CEN on 28 July 2019.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN member.

This European Standard exists in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United Kingdom.

European foreword

The text of ISO 20789:2018 has been prepared by Technical Committee ISO/TC 121 "Anaesthetic and respiratory equipment” of the International Organization for Standardization (ISO) and has been taken over as EN ISO 20789:2019 by Technical Committee CEN/TC 215 “Respiratory and anaesthetic equipment” the secretariat of which is held by BSI.

This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by March 2020, and conflicting national standards shall be withdrawn at the latest by March 2020.

Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN shall not be held responsible for identifying any or all such patent rights.

According to the CEN-CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom.

Endorsement notice

The text of ISO 20789:2018 has been approved by CEN as EN ISO 20789:2019 without any modification.

1 * Scope

This document specifies requirements for so-called “cold bubble-through” or “cold pass-over” humidifying equipment, hereafter referred to as a passive humidifier.Figure 1 and Figure 2 illustrate these passive humidifiers.

NOTE 1 Passive humidifier humidification chambers are at room temperature so they have a lower humidification output than active humidifiers.

This document is also applicable to those accessories intended by their manufacturer to be connected to a passive humidifier.

A passive humidifier integrated into another medical device is subject to the requirements of the standard of the other medical device.

EXAMPLE 1 The requirements in ISO 80601‑2‑69^[⁴^] also apply to a passive humidifier integrated into an oxygen concentrator.

EXAMPLE 2 The requirements in ISO 80601‑2‑70^[⁵^] also apply a passive humidifier integrated into sleep apnoea therapy equipment.

This document does not specify the requirements for active heated humidifiers, heated breathing tubes, or active heat and moisture exchangers (HMEs), the requirements for which are given in ISO 80601‑2‑74.

NOTE 2 ISO 5367 specifies other safety and performance requirements for breathing tubes.

This document is not applicable to a passive HME, which returns a portion of the expired moisture and heat of the patient to the respiratory tract during inspiration without adding heat or moisture, the requirements for which are given in ISO 9360‑1^[⁶^] and ISO 9360‑2^[⁷^].

This document is not applicable to nebulizers used for the delivery of liquids to patients, the requirements for which are given in ISO 27427^[⁸^].

This document is not applicable to equipment commonly referred to as “room humidifiers” or humidifiers used in heating, ventilation and air conditioning systems, or humidifiers incorporated into infant incubators.

An asterisk (*) as the first character of a title or at the beginning of a paragraph or table title indicates that there is guidance or rationale related to that item in Annex A.

This document has been prepared to support the essential principles of safety and performance of a passive humidifier and related accessories as medical devices in accordance with ISO 16142‑1:2016. Annex D maps the clauses and subclauses of this document with the essential principles of ISO 16142‑1:2016.

2 Normative references

3 Terms and definitions

4 General requirements for testing

4.1 Water level

4.2 Passive humidifier test conditions

4.3 * Gas flowrate and leakage specifications

4.4 * Passive humidifier testing errors

5 General requirements

5.1 Mechanical basic safety for all passive humidifiers

5.2 Compatibility requirement

5.3 General requirements for mechanical strength

6 Identification, marking and accompanying documentation

6.1 Legibility and durability of markings

6.2 Markings on the outside of the passive humidifier or its parts

6.3 Units of measurement

6.4 Instructions for use

6.5 Technical description

7 * Humidification output

8 Systems requirements

9 Specific single fault conditions

10 * Cleaning and disinfection

10.1 General

10.2 Home healthcare environment

11 * Breathing system connectors and ports

11.1 General

11.2 Outlet connector

11.3 Flow-direction-sensitive components

11.4 * Accessory port

11.5 Monitoring probe port

11.6 Oxygen inlet port

11.7 Air inlet port

11.8 Filling port

12 * Requirements for the breathing system and accessories

12.1 General

12.2 Accompanying documentation

12.3 Breathing tubes

12.4 Liquid container level

12.5 Filling cap

13 Compatibility with substances

14 * Biocompatibility

15 * Requirements for fire prevention

16 Usability

Bibliography

BS EN ISO 20789:2019

Anaesthetic and respiratory equipment. Passive humidifiers

Current

Published:

31 Oct 2019