Air is the biggest obstacle to steam sterilization. Air must be removed from the chamber and sterilization load before the steam is directly contact the sterilization load and before starting sterilization. This is accomplished by a series of vacuum pulses (the pretreatment stage) in a steam sterilizer before sterilization. A small amount of air is always present in the autoclave, but it must be minimized. Insufficient air clearance, vacuum leakage in the sterilization chamber, and poor steam quality (excess non-condensable gases) are the most common causes of sterilization failures.
Remove the air
The reason for removing air is to expose the sterilization load to steam. Because at temperatures around 121°C,It has a very good sterilization effect, while the same temperature of air (dry air) sterilization effect is very poor. The effective temperature of the air shall be above 160°C. So if you don’t remove all the air, the part of the sterilization load to be sterilized will not be exposed to the steam, but will get trapped in the bubbles on the sterilization load. Then parts exposed to 121°C but with air will not be properly sterilized.
Before any steam sterilization cycle, the air must be removed. There are two ways to remove air. One is gravity air removal. During the sterilization process, all air is removed from the chamber through gravity displacement (steam pushes the air out of the chamber).
The second method of removing the air is to use vacuum system (for a sterilizer with a “pre-vacuum” cycle). We recommend to use vacuum system when steam is difficult to permeate sterilization loads or sterilization loads require long time to drying.
It will has adverse effect of the steam penetration and contact with the sterilized material during the sterilization cycle in autoclave.It is very important to perform regular air removal validation tests in the sterilizer which can prove that residual air has been removed.And it dose not hinder the steam sterilization process. These tests challenge the performance of air removal during the pre-vacuum stage of the sterilizer and may also indicate leaks in the inner chamber or associated piping.
The air removal test kit is placed where air is most likely to be entrapped, and usually placed at the bottom of the sterilizer and near the drain.And it is important to ensure the same prevacuum parameters are used for removing air verification cycle and the production sterilizer cycle.Because this is the only way to test accurately measured the air removal stage performance of the sterilizer.
Pharmaceutical, biotechnology and medical device industries must meet the requirements of the regulation relating to the use of air removal tests in pre-vacuum sterilizer. Air removal tests are used in accordance with the guidelines of the International Organization for Standardization (ISO) and the Association for the Development of Medical Devices (AAMI), the US Food and Drug Administration (FDA), the British Standards Institute (BSI) and the European Standards Committee (EN).Because all organizations vary in the frequency or type of testing, companies can tailor their testing schedules to the risks associated with their particular processes.
Air removal test helps to meet CGMPs Good Manufacturing by demonstrating the effectiveness of the pre-vacuum circulation in the steam sterilizer.It requires that the sterilization process be demonstrated to be effective, controllable, and repeatable.By demonstrating the effectiveness of pre-vacuum circulation in the steam sterilizer, using air removal validation test helps to meet CGMP requirements. Chemical indicators table which obtained from the air removal tests provides evidence for demonstrative purposes.
According to evaluate the quality,business and legal and regulatory risk to confirm the frequency of air removal tests performed.And it must be taken under consideration about the effect of insufficient air removal not detected during the pre-vacuum cycle of the sterilizer.
Insufficient air removal from the sterilizer is directly affected the performance of the sterilizer and then affect the quality of products.If air removal tests are not carried out appropriately and frequently,it may result in a quality assurance investigation covering a large number of products. Based on the survey result, the worst situation is recall non-sterile products.