Biocompatibility evaluation of breathing gas pathways in healthcare applications - Part 3: Tests for emissions of volatile organic compounds (VOCs)
1Key Takeaways
This standard applies to the biocompatibility assessment of gas channels in medical devices, especially the emission test of volatile organic compounds (VOCs). This standard does not involve contamination from respiratory gas sources, but only focuses on potential contaminants inside the gas channel.
2Expert Interpretation
An in-depth interpretation of ISO 18562-3:2017, the test standard for volatile organic compound (VOC) emissions from the respiratory gas pathways of medical devices, covers test methods, acceptance criteria, risk assessment processes, and implementation recommendations. This standard is applicable to the biocompatibility assessment of medical devices such as respiratory therapy equipment and anesthesia workstations.
Overview of the Standard's Core Content
ISO 18562-3:2017 is Part 3 of a series of standards for the biocompatibility assessment of respiratory gas pathways in medical devices. It specifically addresses volatile organic compound (VOC) emission testing. This standard applies to medical devices such as ventilators, anesthesia workstations, and oxygen concentrators, and requires an assessment of the risk of VOC emissions from gas pathway materials during their normal use cycle.
Key test requirements
| Test elements | Specific requirements | Technical basis |
|---|---|---|
| Test type | Type test | Clause 4.1 |
| Sampling point selection | Location representing the patient's inhaled gas characteristics | Clause 5.3(c) |
| Flow rate setting | 20m³/d for adults, 0.21m³/d for neonates | Clause 5.3(d) |
| Analytical method | ISO 16000-6 or ASTM D5466-01 | Clause 5.3(f) |
Acceptance standard system
The standard adopts a three-level exposure classification assessment system:
- Limited exposure (≤24 hours): Tolerable daily intake (TI) ≤360µg/d
- Long-term exposure (24h-30 days): ≤360µg/d on the first day, ≤120µg/d thereafter
- Permanent exposure (≥30 days): Continuous exposure ≤40µg/d
For unidentified compounds, the Threshold of Toxicological Concern (TTC) is used for control. For specific limits, refer to Clause 5.2 of the standard.
Detailed Explanation of the Test Method
The standard requires three stages of sampling:
- Initial stage (when the device is activated)
- After 24 hours
- End of life (or reaching steady state)
Testing should be conducted at the maximum rated ambient temperature to ensure that the device has reached thermal stability (temperature change ≤ 2°C within 1 hour). Materials known not to emit VOCs (such as metals and ceramics) may be exempt from testing.
Implementation Recommendations
Material Selection: Prioritize medical-grade polymers with low VOC emissions and avoid PVC materials containing plasticizers.
Process control: Optimize the degassing process during the manufacturing process and use pretreatment methods such as high-temperature aging to reduce initial VOC release.
Verification strategy: It is recommended to establish a material database and implement fast-track evaluation of verified materials to reduce repeated testing.
Background of technological evolution
This standard fills the gap in the ISO 10993 series on gas pathway assessment. Traditional extraction methods cannot detect gaseous pollutants, while VOCs in the respiratory pathway of medical devices may be directly absorbed through the lungs and have higher bioavailability. The standard innovatively uses the dose-time integral method to calculate the actual patient exposure, which more scientifically reflects clinical risks.