DECONTAMINATION
alcohol-based cleaners on some parts of the instrument, but after reviewing this matter, it was determined that it was not clearly stated to avoid use on the front covers. In addition, in one case study,12
a
catheter connector made from several alternative polymers including polycarbonate was shown to be cracked during service (which could be traced to increased manual cleaning). This cracking allowed bacteria to enter the connector through the intravenous line (IV) and infect the baby that was receiving treatment. Evidence was produced which showed that it was a widespread problem in the mid-1990s in UK hospitals. The investigation suggested that poor design and manufacture of the device were the root cause of the problem.
Using alcohol-based sanitisers and cleaning wipes is often recommended within infection prevention and control strategies and doesn’t consider the consequences this chemical would have on different types of medical devices that haven’t been tested against it by the manufacturer. For example, during the beginning of the current pandemic, the WHO13
published a guideline
where they stated, “If equipment needs to be shared among patients, clean and disinfect it between use for each individual patient (for example, by using ethyl alcohol 70%)”. In addition, some of the authorised biocidal products in the UK14
contain alcohol-based
formulations and are intended for use on surfaces.
Material compatibility and stress resistance
ESC must always be considered15 in
designing parts from polymers. For example, some materials such as fluorinated polymers are not affected by ESC, while others such as polyethylene are highly affected by ESC. Different polymers have different susceptibility to ESC, primarily based on their degree of crystallinity, which refers to the level of structural order and regularity in molecular arrangements of a plastic. The degree of crystallinity is highly associated with level of hardness, density, transparency and diffusion of particular plastic material. All manufacturers of hospital and clinical equipment should provide instruction manuals that show the compatible disinfectants and detergents for cleaning equipment and devices. However, the compatibility testing is not well-understood across the industry, because it is not standardised, does not use validated testing methods, often is only qualitative, and may only list active ingredients which does not consider the other ingredients in a disinfectant or detergent that may damage the device over time. The challenge is even greater now with the increased application of automated decontamination
The increased use of disinfection and cleaning products on medical devices (especially the ones made from plastic) have already been linked with unexpected incidents where these devices failed or became damaged – making an existing problem even bigger and possessing a higher risk for the safety of patients and healthcare staff.
technologies such as hydrogen peroxide vapour (HPV) and ultraviolet-C (UV-C) light. Decontamination technologies may have negative effects on surfaces and devices. This matter is still not well-understood and hasn’t been investigated on a larger scale, as there is a lack of representative testing (e.g., using the actual decontamination technology rather than a drop of H2
O2 on the surface
or using individual UV-C lamps) – real cycle conditions matter in determining the compatibility and effects on surfaces. To reduce the risk of premature ESC failure due to incompatible cleaning solutions, targeted testing designed to screen for ESC incompatibility can be done. The screening process requires understanding key features of the material, such as chemical structure and the molecular weight properties, along with the chemical composition of the solution in question and the application of stress to the polymer’s test sample. These tests16
can be performed by
identifying incompatible chemical/polymer pairs and by accelerated exposure testing. By combining laboratory exposure studies with mechanical testing and an understanding of the likely stresses the part will encounter in use, healthcare institutions and device manufacturers can determine whether a particular plastic is at risk of developing an ESC problem in the future.
PPE decontamination and material compatibility
Healthcare institutions are switching to using reusable items instead of disposable, due to the benefits that they present from an environment point of view and also to reduce costs and avoid having limited supply. There have been numerous reports17
where N95,
FFP3 and other types of medical grade masks were decontaminated by HPV, UV-C light18
and other interventions.
One of the limitations of reusable PPE is that the item in question is supplied without a reliable decontamination method. Most reusable PPE relies on standard wiping and manual cleaning which are highly at risk from human error, with gaps in
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data meaning that some decontamination technologies may also not be compatible. This has created an acute ongoing issue for the healthcare and product manufacturers that requires more research and efforts for reusable PPE, in order to make a significant change for the future. Test Labs is building expertise on how to decontaminate PPE items using HPV, in a way that doesn’t compromise the integrity of the product and, at the same time, effectively kills the pathogenic microorganisms so that these items can safely be used in healthcare. The tested PPE items, such as FFP3 masks and PAPR respirators, are made of diverse materials such as polymers and fabrics. Testing can further assess the compatibility of cleaning and disinfection with these materials. Studies completed by Test Labs and research teams around the world can be used as successful examples of effective method development that not only evaluate process efficacy in removing and deactivating microorganisms, but also consider decontamination technologies and their effects on material compatibility. Deeper understanding of infection prevention strategies employed by healthcare organisations around the world, would improve product development process and assist medical device manufacturers in increasing the lifecycle of their products and, at the same time, make products safer and lower the risk of infection in the healthcare environment.
Conclusion
The acknowledgement of infection prevention and control strategies by medical device manufacturers, and better communication channels between them and healthcare institutions, early on in the product development process, will enable appropriate laboratory testing to prevent issues related to ESC. Test results would guide manufacturers towards materials (e.g., plastics) that are better suited for disinfecting requirements, and away from using 70% ethanol and other incompatible chemicals on products that state ‘mild detergent and cloth’.
SEPTEMBER 2021
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