Conservation of sterile material

All material subjected to a sterilization cycle has a sterilization expiration date. This expiration date will depend on a number of factors, including:

• Type of material used for packaging
• Transport
• Storage conditions

The most important factor is the type of material used to package the material to be sterilized. All this without disregarding the rest of the factors, since failure in one of them will compromise sterility.

Characteristics and classification of packaging materials

The characteristics that a packaging material must meet to allow sterilization are the following:

• Permeability to the sterilization method we are going to use.
• Porosity less than 0.5 mm. This prevents the transfer of microorganisms between the inside and outside of the package.
• Impermeability to humidity.
• Resistance to atmospheric air and manipulation.
• Possibility of sealing, for hermetic closure.
• Non-toxic.
• Must comply with national and international standards.
• It should not give off fibers or any residual material.

Materials can be disposable or reusable. They are classified into three groups:

• Medical grade materials : Manufacturing that meets the required quality standards.
• Non-medical grade materials : Manufacturing that does not meet quality standards and that has no quality guarantee regarding compliance with the necessary characteristics required for proper sterilization.
• Rigid containers .

Packaging materials

The materials used for packaging according to the sterilization method are as follows:

• Metal containers : These are used without perforations for the Poupinel Stove. Heat is transmitted by conduction.
• Medical grade plain paper bag : Also called crepe paper. It is often used to sterilize individual material. It offers less resistance than mixed paper and is opaque, since the content cannot be seen. Ideal for autoclave, ethylene oxide and formaldehyde vapors.
• The medical grade mixed paper bag : Made up of two layers of different materials, one made of bleached cellulose, with an antimicrobial barrier, mechanical resistance and permeable to sterilizing agents. And the other layer of plastic film composed of polyester-polypropylene. Like the previous one, it is ideal for autoclave, ethylene oxide and formaldehyde vapors.
• Non-woven polypropylene : Polymer compatible with autoclave sterilization, ethylene oxide and hydrogen peroxide gas plasma. It is conformable, non-toxic and water repellent.
• Tyvek Mylar : Synthetic polymer compatible with ethylene oxide and hydrogen peroxide gas plasma sterilization. It is impermeable to water, heat sealable, highly durable and has a built-in chemical indicator.

Transport of Sterile Material

According to the Manual for the management of sterilization and disinfection processes for medical equipment from the National Institute for Health Management ( INGESA ), the transport of sterile material to the units must guarantee the complete integrity of the packaging.

Depending on the size or volume of the material, one type of transport or another will be used:

• For bulky material, airtight packaging will be used.
• For small materials, closed plastic bags will be used.

Storage in clinical units and correct handling of sterile material must ensure the continuity of the entire process. And by process we mean packaging, sterilization , sterilization controls , transport and storage.

Storage of Sterile Material

According to INGESA , for the preservation of sterile material to be adequate, the warehouse must meet the following conditions:

• Must have restricted access.
• Its walls must be smooth and easily washable.
• Its temperature should be between 15ºC and 25ºC.
• Humidity should be between 40% and 60%.
• The place must have ventilation with 6 air changes every hour.

Sterile material, before being stored, will be allowed to cool to avoid condensation.

Expiration of sterile material

It has no relation to the sterilization process to which the product has been subjected. According to the National Institute of Health Management, the expiration of sterile material refers to the period of time during which the preservation of sterility can be guaranteed. This expiration will depend mainly on the packaging and storage conditions.

As long as the material is not stored in conditions of excessive humidity and/or temperature, and is not in contact with sources of contamination, the following expiration periods will be accepted depending on the material of the container or packaging:

• Metal containers ( with filter protection if punctured): 6 months.
• The simple medical grade paper bag : 6 months.
• Medical grade mixed paper bag : 12 months.
• Triple barrier (textile, crepe paper, textile) : 3 months.
• Tyvek Mylar : 12 months.