EO gas, or ethylene oxide gas, is a highly effective sterilant commonly used in the medical industry. It is particularly valuable for sterilizing heat- and moisture-sensitive medical devices that cannot withstand traditional moist heat sterilization methods. Our products, syringes and IV sets, are often sterilized using EO gas due to their composition and sensitivity to heat and moisture. These medical devices are typically made of materials like plastics, rubber, and other polymers that may not withstand traditional sterilization methods such as steam or high heat.
EO gas works by penetrating the material of medical devices, effectively killing microorganisms like bacteria, viruses, fungi, and spores. This gas has excellent penetration properties, allowing it to reach even the most intricate parts of complex medical instruments.
To ensure safe and effective sterilization, EO gas is typically used in a controlled environment, such as a sterilization chamber or an EO gas sterilizer. The medical devices are placed inside the sterilization chamber, and EO gas is introduced to create an optimal environment for sterilization. The gas is carefully monitored to maintain appropriate concentration and exposure time, ensuring thorough sterilization while minimizing potential risks.
In some cases, EO gas may be used in mixtures with other gases, such as carbon dioxide or chlorofluorocarbons, to enhance its effectiveness and safety. These mixtures can help improve the sterilization process by reducing EO gas concentration, minimizing potential side effects, and enhancing compatibility with certain materials.
What are the factors affecting the EO effect?
The parameters that primarily affect the lethality of ethylene oxide (EO) sterilization are exposure time, EO concentration, humidity, and temperature. These factors play crucial roles in ensuring the effective elimination of microorganisms while maintaining the safety of the sterilization process.
Exposure time refers to the duration the medical devices are exposed to EO gas. A longer exposure time allows for a more thorough gas penetration into the materials, enhancing the sterilization process. However, it’s essential to strike a balance between sufficient exposure time and avoiding potential harm to the materials or compromising the functionality of the devices.
EO concentration refers to the amount of EO gas present in the sterilization chamber. Higher EO concentrations generally lead to increased lethality, as more gas molecules are available to interact with and kill microorganisms. However, it’s crucial to monitor and control the EO concentration carefully to prevent potential risks associated with excessive exposure.
Humidity plays a critical role in EO sterilization as it affects the efficiency of the process. Higher humidity levels can enhance sterilization effectiveness by promoting the absorption and distribution of EO gas throughout the materials. This is particularly important for devices with porous or complex structures where microorganisms may hide.
When the temperature decreases, the solubility of EO gas in the sterilization chamber increases. This means that more EO gas molecules can dissolve in the available space, resulting in a higher EO gas concentration. In addition, as the temperature decreases, the cooler air has a reduced capacity to hold moisture. This can cause the water vapor present in the chamber to condense, leading to an increase in relative humidity. The higher relative humidity can further enhance the sterilization process by creating an environment that is more conducive to EO gas penetration and microbial inactivation.
The product itself plays a crucial role in the sterilization process, and several factors can affect the effectiveness of EO sterilization.
a) The length and inside diameter of lumens, as well as the permeability of the device’s walls to EO gas, are important considerations. Longer and narrower lumens can present challenges in ensuring adequate gas penetration and distribution throughout the entire length. Additionally, if the walls of the medical device do not allow for the diffusion of EO gas, it can hinder the sterilization process and result in incomplete microbial inactivation.
b) The absorbency of different parts of both the product and materials can impact EO sterilization. Some materials may have higher absorbency, meaning they can absorb and retain more EO gas. This can affect the concentration of EO available for sterilization, potentially reducing its effectiveness. It’s essential to consider the materials used in medical devices and their absorbent properties during the sterilization process.
c) The weights and densities of items also influence the sterilization process. Heavier or denser items may require longer exposure times to ensure sufficient EO gas penetration. The weight of the items can affect gas diffusion and distribution, potentially impacting the sterilization efficacy. Proper consideration of weight and density is crucial for achieving thorough sterilization.
d). Load configuration, particularly for a mixed product load, can impact the effectiveness of sterilization in EO sterilization because several factors must be considered, including proper spacing, separation of incompatible materials, and load balance.
How to ensure the sterilization effect of EO?
To ensure the effectiveness of sterilization, there are a few key steps that can be taken:
a) Confirmation of data recorded during routine processing: Regular monitoring and recording of sterilization process parameters are crucial. This includes parameters such as temperature, pressure, exposure time, EO concentration, and humidity. By comparing these recorded values to the specified sterilization process requirements, one can ensure that the process is being performed within the specified parameters. Any deviations from the specified parameters can be identified and addressed to ensure consistent and effective sterilization.
b) Confirmation of no growth from biological indicators: Biological indicators (BIs) are used to validate the effectiveness of the sterilization process. These indicators consist of a known population of microorganisms, typically highly resistant to the sterilization method being employed. After the sterilization cycle, the BI is incubated under appropriate conditions to check for any microbial growth. If there is no growth observed, it provides confirmation that the sterilization process was successful in eliminating the test organism. This step helps ensure that the sterilization cycle has achieved the desired level of microbial inactivation.
By implementing these validation steps, medical device manufacturers can ensure that the sterilization process is effective in eliminating microorganisms and maintaining the safety of medical devices. It is crucial to follow industry guidelines and regulations.
Considerations for Medical Devices/Sterile Barrier Systems
a) When it comes to medical devices, the sterile barrier systems, and the ink on them, it’s crucial to consider their ability to withstand various conditions. High humidity and temperature, typically up to 60 °C, along with multiple deep vacuums, nitrogen, and EO (ethylene oxide), are some of the factors to keep in mind. Different sterilization cycles may have specific temperature and humidity ranges that must be considered. It’s important to ensure that the materials used in these systems can tolerate these conditions to maintain their functionality and sterility
b) The medical device should allow gas to infiltrate through certain areas while ensuring continuous contact with different parts of the device. This ensures that the gas can effectively reach and sterilize all the necessary components. Proper design and construction of the device should be considered to allow for optimal gas flow and contact. This will help maintain the desired level of sterility throughout the device.
c) Sterile barrier systems should have gas-permeable areas that allow gas to enter and exit. The velocity of gas passing through the permeable portion should be such that it maintains the integrity of the sterile barrier system during vacuum and/or inflation. It should be ensured that the placement of the sterile barrier system and/or each sterile barrier system in the packaging system does not impede its permeability. Avoid close contact of breathable materials with impermeable materials, so as not to hinder gas permeation.