Five common sterilisation methods for medical devices

In daily life, each type of sterilisation has different requirements for medical device packaging materials, for example, for medical devices with very long catheters,

ethylene oxide sterilisation may be difficult to reach the centre of the lumen, thus affecting the sterilisation effect;

some medical devices with sensitive electronics may be affected when sterilised by gamma radiation or e-beam sterilisation,

so don’t let the wrong sterilisation method ruin your medical devices. Sterilisation of medical devices

Below we can take a look at five common methods of sterilisation, and before we do, we should clarify the definition of sterilisation:

Definition of sterilisation

Sterilisation is the process of confirming that a product is free of any form of viable microorganisms (State Drug Administration .

Production management specification for sterile medical instruments . Sterilisation is the technique of killing or removing all microbial propagules and spores or spores.

Sterilisation involves the sterilisation of plants, equipment, containers, sanitary ware, working clothes, raw materials, finished products, packaging materials, instruments and so on.

In particular, certain products, such as stents and intravascular catheters, medical sutures and needles, contact lens care fluids, or disposable infusion sets, and other medical devices that have an effect by directly or indirectly coming into contact with the human body’s blood and fluids, are subjected to strict requirements for aseptic examination, and efforts should be made to eliminate microbial contamination during the production process.

In the production process, efforts should be made to eliminate microbial contamination and kill microorganisms in the product, which is the purpose of sterilisation.

Microorganisms include bacteria, fungi, viruses and so on. Different types of microorganisms are sterilised in different ways, and the sterilisation effect is also different.

Common sterilisation methods are basically the following: dry heat sterilisation, moist heat sterilisation, radiation sterilisation, gas sterilisation, filtration and sterilisation.

<1> Dry Heat Sterilisation

Put the articles in the dry heat sterilisation cabinet (box), use dry heat air to kill microorganisms or eliminate pyrogenic substances.

Scope of application: glass appliances, metal appliances, high temperature resistant but not suitable for wet heat sterilisation method of sterilisation of the goods, can be used in this method of sterilisation.

Dry heat sterilisation conditions are generally (160-170 ℃) × 120min or more, (170-180 ℃) × 60min or more or 250 ℃ × 45min or more.

When using dry heat sterilisation, the sterilised items should be loaded in an appropriate way, and should not be arranged too densely, in order to ensure the effectiveness and uniformity of sterilisation.

The most commonly used bioindicator for dry heat sterilisation is Bacillus subtilis spores.

<2> Moist Heat Sterilisation

The items will be placed in the sterilisation cabinet (pot), the use of high-pressure saturated steam to make microbial organisms in the protein, nucleic acid denaturation and thus kill microorganisms. This method has strong sterilisation ability and is the most effective and widely used sterilisation method in heat sterilisation.

Scope of application: buffer, culture medium, clean clothes, glass appliances, infectious dirt and other items that do not change or damage when exposed to high temperature and high humidity.

Moist heat sterilisation is usually 121 ℃ × 15min or 121 ℃ × 30min, when sterilised, the sterilised items should be properly loaded, can not be arranged too closely to ensure the effectiveness and uniformity of sterilisation.

The most commonly used bioindicator for moist heat sterilisation is thermophilic Bacillus subtilis spores.

<3> Gas Sterilisation

The gas formed by chemical disinfectants is used to kill microorganisms. Gas sterilisation can be subdivided into ozone sterilisation and ethylene oxide sterilisation.

Ozone Sterilisation

Ozone has a strong bactericidal disinfection. The principle of sterilisation is: ozone is unstable in the molecular structure at room temperature and pressure, and soon decomposes itself into oxygen and individual oxygen molecules, which have strong activity and strong oxidative effect on bacteria, and ozone oxidises and decomposes the enzymes necessary for oxidising glucose in bacteria, thus destroying their cell membranes and killing them.

<4>Radiation Sterilisation

Ionising radiation

Sterilisation with X-rays and γ-rays that cause ionisation.

The lethal effect of ionising radiation on microorganisms is mainly due to the changes in intracellular biochemistry.

Radiation of medicines, food safety issues: radiation sterilisation for medicines or food should be tested for safety, it is necessary to carry out a scientific and comprehensive evaluation of the high dose of radiation should be more cautious.

<5> Filtration method for removing microorganisms

Physical methods to remove microorganisms in the medium. Often air or liquid microorganisms and impurities in the membrane filter made of different materials to get sterile, impurity-free air or liquid.

Virus filter membrane pore size of 25 ~ 100nm; filtered bacteria filter membrane pore size of 0.22 ~ 0.45μm



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