ISO 20789:2018

Overview

ISO 20789:2018 - Anaesthetic and respiratory equipment - Passive humidifiers defines safety, performance and testing requirements for respiratory passive humidifiers commonly described as cold bubble-through or cold pass‑over devices. The standard covers the humidifier and its accessories as a complete system up to the patient‑connection port, with emphasis on preventing respiratory tract drying and ensuring predictable humidification performance in both healthcare and home‑care settings.

Key topics and technical requirements

ISO 20789:2018 addresses device-level and system-level requirements, including:

• Scope and terms: Definitions for passive humidifier types and system components.
• Test conditions and general testing requirements: Specified procedures for water level, gas flowrate, leakage and measurement uncertainties to determine humidification output.
• Mechanical safety and strength: Stability, resistance to unwanted lateral movement, mechanical integrity and requirements derived from relevant medical electrical safety standards.
• Acoustic, overflow and overpressure protection: Limits and design requirements to reduce audible noise, spillage and pressure hazards.
• Compatibility and connectors: Requirements for breathing system connectors, inlet/outlet ports, accessory ports and flow‑direction sensitive components to ensure safe integration with tubing and ventilators.
• Identification, marking and documentation: Durable markings, symbols, units, warnings, installation/start‑up and maintenance instructions, unique version identifiers and technical descriptions.
• Hygiene and biocompatibility: Cleaning, disinfection, sterilization guidance and biocompatibility requirements for materials that contact patient gases or fluids.
• Usability, fire prevention and single‑fault conditions: Design guidance to reduce user error, ensure safe behaviour under faults and minimize fire risk.
• Annexes: Informative guidance, symbol lists, terminology and a normative method for determination of humidification output.

Practical applications and users

ISO 20789:2018 is intended for:

• Manufacturers of passive humidifiers and breathing system accessories - to design, test and label products that meet international safety and performance expectations.
• Biomedical engineers and test laboratories - for setting up compliant test protocols and system performance verification.
• Regulators and procurement teams - to assess conformity and select devices for hospitals and home‑care programs.
• Clinical users and respiratory therapists - for understanding device limitations, cleaning/maintenance, and safe integration with ventilators and oxygen delivery systems.

Benefits include improved patient safety (reduced airway desiccation and obstruction risk), clearer performance disclosure (humidification output), better system compatibility and harmonized cleaning/marking practices.

Related standards

• ISO 80601‑2‑74 (active humidifiers) - for heated humidification systems and essential performance.
• ISO 8185:2007 - portions replaced by ISO 20789.
• IEC 60601‑1‑11 - referenced for mechanical strength and home healthcare considerations.

Keywords: ISO 20789:2018, passive humidifiers, cold bubble-through, cold pass-over, humidification output, anaesthetic and respiratory equipment, medical device standard.