PERSONAL P ROT ECT ION EQUI PMENT
l Steam Sterilisation of Surgical Masks made from sterilisation wrap (France)
l Automated Cleaning & Disinfection of reusable PPE equipment
l Steam Disinfection 105˚C as a backup option for FFP2 respiratory Masks
FFP2 / N95 masks have become very scarce in many markets around the world during this crisis. Various methods for their reprocessing have been proposed by different stakeholders such as hospitals, universities, governmental agencies, non- profit organisations, PPE manufacturers or sterilisation companies to alleviate the shortage. Some health authorities have already officially approved certain methods or declared that they would give more liberty to hospitals and companies to implement crisis measures than under normal circumstances, as long as the basics of infection control, biomedical engineering and risk management is considered. Measures proposed include (non- conclusive list): l Gamma sterilisation l UV light disinfection l Low temperature sterilisation with H2
O2
l Low temperatures sterilisation with ETO l Thermal disinfection with dry heat 65-75˚C / 150˚-160˚F
l Thermal disinfection with moist heat at 60-80˚C
l Thermal disinfection with moist heat at 105˚C
l Steam Sterilisation with a pre-vacuum 121˚C / 250˚F 15-20 min cycle.
Each method has advantages and disadvantages. This paper provides information on some of the key approaches.
Steam sterilisation
In the case of steam sterilisation at 121˚C / 250˚F advantages include broad availability in hospitals, quality assured workflow and it is easy to implement – based on established CSSD (Central Sterile Supply Department) workflows and processes. This solution also offers very high sterilisation safety against all infectious agents, which could be critical when present in a facemask (including SARS-CoV-2). With steam sterilisation, there is no risk of potentially harmful process
Example of FFP2 mask types with recommendations for reprocessing, according to the Dutch Ministry of Public Health.
residues within the masks (as opposed to chemical low temperature sterilisation processes such as H2
O2 or EtO).
Disadvantages include: not all masks are suitable for the process, there is limited published data on the impact on filtration efficacy, there may be possible changes in the fit of masks due to steam sterilisation for some models, and it is dependent on the way masks are packed and treated during the whole reprocessing workflow. The method of reprocessing certain respirator masks by standard steam sterilisation with a pre-vacuum 121˚ / 250˚F, for a 15-minute or 20-minute cycle, has been proposed by research teams in Austria and in the Netherlands.
This has led to an edict from the Austrian
Ministry for Health to reprocess suitable FFP2 masks with 121˚C / 250˚F steam sterilisation and reuse them once. The Dutch Ministry of Public Health has published test results showing that a specific FFP2 mask type can be re-sterilised at least twice without significant change in its filtration or fitting properties.
The German Society of Sterile Supply (DGSV) has also expressed their preference for the steam sterilisation approach, citing arguments of workflow, safety and quality assurance with existing infrastructure. However, the official healthcare authorities have taken a different position to date, by recommending dry-air decontamination. Before the health authority recommendation
During the COVID-19 pandemic many countries have encouraged more extensive use of medical face masks in healthcare and also in everyday life. As a consequence, a massive increase in consumption of single-use medical face masks has depleted stocks.
66 l
WWW.CLINICALSERVICESJOURNAL.COM
was issued, many German hospitals implemented the steam sterilisation process and are currently evaluating both options. It is important to emphasise that not all FFP2 / N95 masks can be reprocessed this way. Information about which masks are suitable according to their tests can be found in the reference section, located on the homepage of the research group from TU- Delft and health authority letters from Austria and the Netherlands.
There is no suitable non-detrimental cleaning process for FFP2 / N95 masks. One important principle in sterilisation sciences is “... what is not clean cannot be sterilised”. The reprocessing of single-use masks therefore cannot be considered a “sterilisation process” but should rather be called a “decontamination process”, using a standard sterilisation process. Microbicidal efficacy of steam sterilisation is much more robust to the presence of residual soil than chemical sterilisation processes (H2
O2 ,
ethylene oxide, formaldehyde etc.). Steam sterilisation generally has a higher margin of safety than these chemical-based methods, which can be seen as a critical advantage.
Implementation in Austria, Germany and the Netherlands: Based on the described legal and scientific background in those three countries, Belimed has installed sterilisation programmes for the purpose of FFP2/N95 mask reprocessing with medical steam sterilisers. In addition, the company has validated and tested the sterilisation conditions on-site in various hospitals in countries where authorities have officially recommended this practice – so far, in Austria, Germany and the Netherlands. The steam sterilisation process found most suitable for this purpose, is a fractionated pre-vacuum process with 121˚C/250˚F. This process generally needs to be installed and tested in specific hospitals interested in this contingency measure. Before the reprocessing of masks
OCTOBER 2020
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