Explained: Silicone sound abatement foam used in DreamStation 2 and the sleep and respiratory care devices remediated as part of the June 2021 Philips Respironics recall*
* This is a recall notification in the US and field safety notice in other countries
As a leading health technology company, our first priority at Philips is patient safety and quality. We understand how important Philips Respironics’ sleep therapy devices and ventilators are to patients that use them and how they improve their lives every day and night.
We deeply apologize for the distress and concern that Philips Respironics’ voluntary June 2021 recall* has caused for patients and care providers, and continue to work hard to resolve this for our patients and business customers. Globally, Philips Respironics has now remediated more than 99% of the actionable sleep therapy device registrations to date and continues to work on remediation of affected ventilators.
We have received a number of questions about the silicone sound abatement foam used in repaired and new replacement devices, as well as widely in the industry. We believe it is important that patients, care providers and business customers have access to accurate information and, most importantly, that they know that the foam is safe.
The repair and replacement program, which includes replacement of the PE-PUR sound abatement foam with silicone foam, is being implemented in consultation with the relevant competent authorities, including the US Food and Drug Administration (FDA). Devices with silicone sound abatement foam have been subject to extensive testing in accordance with the applicable regulatory standards, and Philips Respironics has not identified any safety issues.
In November 2021, FDA asked Philips Respironics to further test the silicone foam for volatile organic compounds (VOCs). This testing has been completed in accordance with the relevant industry standard (ISO 18562-3; see below for more information). Any VOCs emitted by devices with silicone foam during this testing were significantly below the applicable toxicological thresholds. This included formaldehyde, which was also significantly below the applicable FDA and World Health Organization (WHO) thresholds. The final reports of that testing were submitted to FDA in August 2022.
Multiple independent, certified laboratories conducted the testing on behalf of Philips Respironics. Harmonization of toxicological thresholds is critical for interpretation across these laboratories. This is best practice and consistent with medical regulatory authorities’ practices. Philips Respironics proposed to the test laboratories to use the applicable WHO limit for formaldehyde. This limit is more conservative than the FDA limit: the FDA has recently released its own internationally harmonized formaldehyde limit that is more than two times higher than the WHO limit.
The purpose of a test according to ISO-18562-3 is to determine if a detected and quantified VOC is likely to be associated with a toxicological risk based upon exposure during use of the device. Importantly, there is a big difference between a hazard, which is something that – at certain levels – has the potential to cause harm, and a risk, which is the likelihood that a hazard will cause harm.
For example, formaldehyde, like many other compounds, is omnipresent in daily life. It is present in the human body, certain food (e.g., pears, cauliflower), cardboard, carpeting, etc. Formaldehyde can be a hazard, but it is only considered a risk when the exposure levels are above the applicable regulatory thresholds. Based on the extensive testing by multiple independent, certified laboratories, none of the VOCs, including formaldehyde, exceeded those thresholds.
FAQs
The repaired and new replacement sleep therapy devices all contain silicone sound abatement foam. Silicone is a widely applied rubber-like material that is used in many applications of daily life, such as bakeware for cupcakes, and also in medical applications, including sleep therapy devices. This includes sleep therapy devices manufactured by other companies. Were any changes made to the silicone foam as a result of testing?
What material is used for sound abatement in the DreamStation 2 and other replacement devices?
What is the status of the testing on the silicone foam that FDA requested?
Silicone foam volatile organic compound testing as requested by FDA in November 2021 (i.e. device testing according to ISO 18562-3) has been completed. The final reports were submitted to FDA in August 2022.
What is volatile organic compound testing on devices testing according to ISO 18562-3?
The purpose of such a test is to determine if a detected and quantified volatile organic compound is likely to be associated with a toxicological risk based upon exposure during use of the device. This testing is performed on the entire device, not just the sound abatement foam component. ISO 18562-3 ‘Biocompatibility evaluation of breathing gas pathways in healthcare applications – Part 3: Tests for emissions of volatile organic compounds’ is the FDA recognized standard to conduct such tests.
These are very sensitive measurements, because the concentrations that are measured during such tests are typically in the range of µg/m3, or one millionth of a gram of a volatile organic compound per one thousand liters of air that is emitted by the device.
The silicone sound abatement foam used by Philips Respironics in the replacement devices has been shown in some tests to emit chemicals, including formaldehyde. Can you explain this?
The levels of formaldehyde detected in all devices that contain silicone sound abatement foam were well below the formaldehyde limit established by the World Health Organization, a global public health authority. Additionally, the levels detected were even further below the more recent formaldehyde limit established in 2023 by FDA, as well as other medical authorities.
In this respect, it is important to distinguish between a hazard, which is something that – at certain levels – has the potential to cause harm, and risk, which is the likelihood that a hazard will cause harm. For example, acetone is a common chemical found in plastics and specifically in nail polish remover. Hazards associated with acetone include skin irritation, dizziness, etc., but acetone is not a risk under normal exposures. Similarly, formaldehyde is omnipresent in daily life. It is present in the human body, certain food (e.g., pears, cauliflower), cardboard, carpeting, etc. Formaldehyde can be a hazard, but it is not considered to be a risk when the exposure levels are below the applicable regulatory limits.
The determination of chemical levels and safety is not made by Philips Respironics but by the testing laboratories per FDA recognized standards. The general process is:
No. Philips Respironics’ devices with silicone sound abatement foam have been subject to extensive testing in accordance with the applicable industry testing standards, and Philips Respironics has not identified any safety issues.
The comprehensive testing and research program also includes an in-depth review and reassessment of data and toxicological risk assessments done prior to June 2021. This included a review of the single volatile organic compound test of a Philips Respironics A Series device containing silicone foam, which was referenced in the November 2021 FDA Form-483 for a Philips Respironics site. The detected volatile organic compounds were below the applicable FDA and WHO regulatory limits.
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