How long are autoclaved packs sterile

University of Guelph Veterinary Surgery. Academics Campus Libraries Research Services. Login Technical Help Home. Search Vet Surgery Search this site:. My Books 1. Surgical Preparation. Suture Materials and Suture Patterns. Abdominal Surgery. Spay Ovariohysterectomy. Cesarian Section. Castration Orchiectomy. Exploratory Celiotomy Laparotomy. Gastric Surgery. Intestinal Surgery. Before we explain how long items remain sterile after autoclaving, it is important to understand the sterilisation process that occurs within the autoclave.

Autoclaves conduct sterilisation by heating up instruments above boiling point. The primary agent in this process is steam, which is known to be a great agent for killing varieties of microorganisms such as bacteria and spores.

Moreover, moist heat is known to be more effective than dry heat when it comes to actually transfer heat. This is why autoclaves are very important especially in the medical industry which deals with a lot of substances and foreign agents. The sterilisation process of autoclaving begins by removing all air within the chamber to create a low-pressure environment. Another reason for removing all air within the chamber is so that it does not dilute the steam that enters the chamber at the beginning of the process.

Once all the air is removed, steam will then be generated to destroy any present microorganisms. The steam will be pumped into the chamber at a certain level of pressure for a few minutes. This creates a conducive sterilisation environment that is based on three elements: high temperature, dry steam pressure, and heat transfer ability of moist steam. Once the procedure is finished, the instrument will be dried. The drying time will be dependent upon the wetness of the steam and other factors.

The period of sterility is dependent upon different factors. For example, the sterility of an instrument can be dependent on the package or wrapper material it is contained in. Written and illustrated procedures for preparation of items to be packaged should be readily available and used by personnel when packaging procedures are performed All items to be sterilized should be arranged so all surfaces will be directly exposed to the sterilizing agent.

Thus, loading procedures must allow for free circulation of steam or another sterilant around each item. There are several important basic principles for loading a sterilizer: allow for proper sterilant circulation; perforated trays should be placed so the tray is parallel to the shelf; nonperforated containers should be placed on their edge e.

Studies in the early s suggested that wrapped surgical trays remained sterile for varying periods depending on the type of material used to wrap the trays. Safe storage times for sterile packs vary with the porosity of the wrapper and storage conditions e.

The 3-mil polyethylene is applied after sterilization to extend the shelf life for infrequently used items Supplies wrapped in double-thickness muslin comprising four layers, or equivalent, remain sterile for at least 30 days. Any item that has been sterilized should not be used after the expiration date has been exceeded or if the sterilized package is wet, torn, or punctured.

Although some hospitals continue to date every sterilized product and use the time-related shelf-life practice, many hospitals have switched to an event-related shelf-life practice. This latter practice recognizes that the product should remain sterile until some event causes the item to become contaminated e.

Event-related factors that contribute to the contamination of a product include bioburden i. There are data that support the event-related shelf-life practice One study examined the effect of time on the sterile integrity of paper envelopes, peel pouches, and nylon sleeves.

The most important finding was the absence of a trend toward an increased rate of contamination over time for any pack when placed in covered storage Another evaluated the effectiveness of event-related outdating by microbiologically testing sterilized items. During the 2-year study period, all of the items tested were sterile Thus, contamination of a sterile item is event-related and the probability of contamination increases with increased handling Following the sterilization process, medical and surgical devices must be handled using aseptic technique in order to prevent contamination.

Sterile supplies should be stored far enough from the floor 8 to 10 inches , the ceiling 5 inches unless near a sprinkler head [18 inches from sprinkler head] , and the outside walls 2 inches to allow for adequate air circulation, ease of cleaning, and compliance with local fire codes e. Medical and surgical supplies should not be stored under sinks or in other locations where they can become wet.

Sterile items that become wet are considered contaminated because moisture brings with it microorganisms from the air and surfaces. Closed or covered cabinets are ideal but open shelving may be used for storage. Any package that has fallen or been dropped on the floor must be inspected for damage to the packaging and contents if the items are breakable.

If the package is heat-sealed in impervious plastic and the seal is still intact, the package should be considered not contaminated. If undamaged, items packaged in plastic need not be reprocessed. The sterilization procedure should be monitored routinely by using a combination of mechanical, chemical, and biological indicators to evaluate the sterilizing conditions and indirectly the microbiologic status of the processed items.

The mechanical monitors for steam sterilization include the daily assessment of cycle time and temperature by examining the temperature record chart or computer printout and an assessment of pressure via the pressure gauge. Generally, two essential elements for ETO sterilization i.

Chemical indicators are convenient, are inexpensive, and indicate that the item has been exposed to the sterilization process. In one study, chemical indicators were more likely than biological indicators to inaccurately indicate sterilization at marginal sterilization times e.

Chemical indicators should be used in conjunction with biological indicators, but based on current studies should not replace them because they indicate sterilization at marginal sterilization time and because only a biological indicator consisting of resistant spores can measure the microbial killing power of the sterilization process. Chemical indicators are affixed on the outside of each pack to show that the package has been processed through a sterilization cycle, but these indicators do not prove sterilization has been achieved.

Preferably, a chemical indicator also should be placed on the inside of each pack to verify sterilant penetration. Chemical indicators usually are either heat-or chemical-sensitive inks that change color when one or more sterilization parameters e.

Chemical indicators have been grouped into five classes based on their ability to monitor one or multiple sterilization parameters , An air-removal test Bowie-Dick Test must be performed daily in an empty dynamic-air-removal sterilizer e.

Biological indicators are recognized by most authorities as being closest to the ideal monitors of the sterilization process , because they measure the sterilization process directly by using the most resistant microorganisms i.

Since the Bacillus spores used in biological indicators are more resistant and present in greater numbers than are the common microbial contaminants found on patient-care equipment, the demonstration that the biological indicator has been inactivated strongly implies that other potential pathogens in the load have been killed An ideal biological monitor of the sterilization process should be easy to use, be inexpensive, not be subject to exogenous contamination, provide positive results as soon as possible after the cycle so that corrective action may be accomplished, and provide positive results only when the sterilization parameters e.

Biological indicators are the only process indicators that directly monitor the lethality of a given sterilization process.

Spores used to monitor a sterilization process have demonstrated resistance to the sterilizing agent and are more resistant than the bioburden found on medical devices , , Steam and low temperature sterilizers e. If a sterilizer is used frequently e. Each load should be monitored if it contains implantable objects. If feasible, implantable items should not be used until the results of spore tests are known to be negative.

Originally, spore-strip biological indicators required up to 7 days of incubation to detect viable spores from marginal cycles i.

The next generation of biological indicator was self-contained in plastic vials containing a spore-coated paper strip and a growth media in a crushable glass ampoule. A rapid-readout biological indicator that detects the presence of enzymes of G. The rapid-readout biological indicator is a dual indicator system as it also detects acid metabolites produced during growth of the G.

This system is different from the indicator system consisting of an enzyme system of bacterial origin without spores. Independent comparative data using suboptimal sterilization cycles e. A new rapid-readout ETO biological indicator has been designed for rapid and reliable monitoring of ETO sterilization processes. The rapid-readout ETO biological indicator detects the presence of B.

The fluorescence indicates the presence of an active spore-associated enzyme and a sterilization process failure. This indicator also detects acid metabolites produced during growth of the B. This was expected because the enzyme is relatively ETO resistant and is inactivated at a slightly longer exposure time than the spore.

The standard biological indicator used for monitoring full-cycle steam sterilizers does not provide reliable monitoring flash sterilizers