DECONTAMINATION
Improving VH2O2 sterilisation monitoring
Richard Bancroft and Brisia López-Ortega outline best practice when monitoring sterilisation processes involving the use of vaporised hydrogen peroxide.
Over the last decade, vaporised hydrogen peroxide (termed VH2O2) has been rapidly adopted as the hospitals’ method of choice for sterilisation of heat labile medical devices. It has also gained increased use industrially for sterilising single use and combination (drug/device) devices. The advantages of VH2O2 in these applications are quite significant; the process has excellent efficacy, cycle times as short as 16 minutes, no post-processing aeration is required, and there are none of the residual toxicity problems associated with some other sterilisation methods.
VH2O2 low temperature sterilisers have been specifically designed to process goods using vaporised hydrogen peroxide under vacuum conditions. The sterilisation cycles are fully automated, with different pre-programmed cycles available to accommodate varying loads and medical devices.
There are basically three types of VH2O2 sterilisers commercially on the market: 1) VH2O2
2) VH2O2 with plasma and 3) VH2O2 with ozone
It is important to acknowledge the active sterilising agent is only vaporised hydrogen peroxide, the plasma and ozone used by some commercial processes are used to help eliminate the hydrogen peroxide (H2
O2
provide a concentration process and the VH2O2 delivered into the steriliser chamber will be at a significantly higher concentration than those processes that do not concentrate the VH2O2.
) residuals. With some variations and different parameters, all commercial VH2O2 sterilisation cycles consist of three stages: conditioning, sterilisation and aeration. VH2O2 sterilisers utilise H2
O2 O2
form, vaporising it into its gaseous form. In its liquid state, H2
is generally provided at
between 50 and 59% concentration. When transformed into a gas, some processes
These variations are manufacturer and sterilisation-cycle dependent. Also, the contact time with VH2O2 will vary from one sterilisation cycle to another, making each commercial VH2O2 sterilisation cycle type unique. This is a major difference when compared to steam sterilisation, where many of the parameters are identical across may commercial manufacturers. The variations of VH2O2 sterilisation processes make cycle monitoring much more complex for VH2O2 cycles.
in its liquid
Current practice for VH2O2 monitoring The use of VH2O2 sterilisation, like any other sterilisation method, requires validation and subsequent routine control
Good practice sterilisation monitoring consists of three separate steps: steriliser monitoring, cycle monitoring and pack monitoring.
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and monitoring. Each sterilisation method requires a different approach, due to the varying critical process variables of the method used. The methods of sterilisation process validation and control are generally addressed in international standards that are supported by regional guidance documents. These guidance documents allow more specificity in their requirements, allowing alignment with local practices and regulatory requirements. For VH2O2 sterilisation, the recently published ISO standard, ISO 22441, Sterilization of health care products – Low temperature vaporized hydrogen peroxide – Requirements for the development, validation and routine control of a sterilization process for medical devices, provides guidance for the validation and routine control of processes for vaporised hydrogen peroxide.
One of the approaches used for parametric release allows routine release of terminally sterilised products on the basis of successful demonstration that predetermined and validated sterilising conditions have been achieved. Data derived from in-process controls and by monitoring relevant sterilisation parameters can provide accurate and relevant information to support sterility assurance of the product.
Whether biological indicators are used
as part of routine monitoring relies on the practices of the healthcare facility as well as the local, national and/or regional standards. Biological indicators are used in several countries in Europe and North America – for example, this allows users of such sterilisation processes to choose how they wish to routinely monitor these processes. Sterilisation modalities have process variables defined as variables that directly influence microbiocidal efficacy. In order to deliver these variables consistently, cycle variables control the delivery of the sterilising agent. For VH2O2 sterilisation, the key cycle variables are: temperature (chamber and vaporiser), pressure, time, and hydrogen peroxide concentration.
Hydrogen peroxide concentration is JANUARY 2023
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