ANSI AAMI ISO 11134:1993 pdf download – Sterilization of health care products – Requirements for validation and routine control Industrial moist heat sterilization
A maintenance scheme should be developed from the schedules provided by the sterilizer manufacturer, instrument manufacturer(s) and equipment manufacturer(s), from the generic tasks and tests carried out in the plant and as a result of experience. The maintenance scheme and frequency with which each task is carried out should be based on the recommendations given by the manufacturer and persons with specialized experience. In addition, usage, risk to safety and the need to maximize utilization should be considered. The procedure for each maintenance task should be based on manufacturer’s instructions. The designated person should sign and date all entries relating to maintenance, both scheduled and unscheduled, stating that all the necessary work and tests have been completed and are satisfactory. Recurring faults should be identified and corrective action taken.
A.6.1 Selection of the type of sterilization cycle to be used depends upon the product configuration and the ability of the product and package to withstand temperatures, pressure stresses and total heat input.
A.6.1.1 Moist heat sterilization of health care products can be complex because of the heterogeneity of product types, product packaging and vessel loading configurations that may be encountered. Factors that can influence moist heat sterilization of health care products are listed in Table A.2. Multicomponent products can have matted surfaces where the steam penetration necessary for sterilization might not occur. A dry heat sterilization situation could exist and cycle development using dry heat techniques (e.g., indicator organisms) could be necessary.
A.6.1.2 Cycle development studies may be performed in a research vessel if process equivalency with the product vessel is demonstrated. Moist heat processes should be developed with the narrowest practical range of temperatures within the sterilization chamber. Prevacuum saturated steam processes are inherently easier to control while, for example, a steam-air or pressurized water cycle can potentially have a greater temperature band. The validation process in terms of the number of repetitive cycles might have to be adjusted based on the process to demonstrate adequately the control desired.
A.6.1.3 The moist heat process that is easiest to control and validate is a saturated steam process with mechanical air removal. Such processes involve a single component, single phase process, which is inherently simpler to control. The two variables of greatest concern in these processes are the ability to remove air from dense porous loads and the maintenance of saturated steam conditions. Excessive moisture can result in wet porous loads, packaging damage or spotting. Producing a saturated steam environment by air venting or gravity displacement of air leads to some uncertainty about achieving a single component (steam) atmosphere. Removal of air from porous materials is a greater concern. The loading pattern in the sterilizer chamber is critical both to ensure air removal from a package and to permit adequate steam flow for the displacement of the air. The latter, for example, requires sufficient vertical channels in the product load. Additional validation or inclusion of a denser pattern of temperature monitors may be required for such cycles.
A.6.1.4 Moist heat sterilization of sealed containers with liquid and gas phase may require external pressures greater than those provided for just heating. If the contained liquid is water, (or a solution with similar physical properties) the vapor pressure produced by heating cannot, during the heat-up and exposure phase, exceed the pressure of the heating media. However, additional pressure is produced by heating of the vapor space (e.g., air) and by expansion of the liquid which compresses the vapor. It is typical to add external pressure greater than required to compensate for these heat-up and exposure phases. This compensates for interior pressures caused by the interior temperatures and vapor pressure being greater than the cooling media.