Q - How can you defind a varying load in sterilant?
Answer -Usually the load selection is done by reviewing all the products in the sterile family and making a judgement. It may be helpful to get a bunch of product samples on a table in the conference room, and have a meeting with the people who are involved with the sterilization or have knowledge of sterilization. Usually, the selection is then made based on a combination of items ---- products that may be the heaviest, densest products, or those with the most complicated design, or with the most difficult tubings, pathways, internal lumens, closed-off tubings etc., are there any gauzes or cottons that may have high bioburdens and absorb more EO than metals or glass? Also, how much packaging material is used on the different products, and do the packaging materials absorb humidity & EO, or do the packaging materials restrict the exchange of heat, EO, humidity. You then also need to look at the case configuration & pallet configuration --- are there sterilizer loads or load configurations that will be particularly resistatant to heat-up, or will absorb abnormal amounts of EO?
Document the results of the product review meeting, so it can be added to your validation protocol.
If you cant decide which product or load configuration, you may need to run a few fractional/sublethal cycles at your sterilizer, with candidate loads, to see which load has the worst heat&humidity profiles, and/or which loads show the most survivors (fractional cycle) with sample test products that have internal BIs. This may take longer and cost more than originally planned for the validation, but it is important that it gets done right the first time.
View related training - Ethylene Oxide Sterilizer Validation: Basic Requirements