Dry Temperature Sterilization Method

The death of microorganisms occurs slowly in the process of coagulation of the cell protein by oxidation. It can only be used in units where steam sterilisation is not possible due to the unreliability of the control parameters, the inability to easily control the homogeneous distribution of heat in dry heat sterilisers, the long duration of the process and the high temperature damaging the instruments in a long time. 
Dry temperature sterilisation temperature degrees and times:
 
150 o C' 2,5 hours
160 o C' 2 hours
170 oC' 1 hour
 
The time is started after the temperature in the steriliser has risen to the desired temperature. This excludes the time required for the temperature to penetrate the packaged material and for the temperature to drop to room temperature at the end of the process. 
 
Advantages
Non-toxic,
Safe for the environment,
Suitable for powders (powder), petrolatum, glycerine 
 
Disadvantages
Long duration, very high temperature required
For large materials, it takes a long time for the heat to penetrate.
Not suitable for fabric and rubber materials.




 
 Pressurised Steam Sterilization Method

 
When saturated vapour at a certain temperature encounters a colder material, it immediately condenses on the material. During condensation, it gives its melting temperature to the material and the material quickly reaches the temperature of the vapour. Meanwhile, the thin layer of water formed on the material provides a lethal effect on microorganisms. Four factors affect the sterilisation process: saturated steam, temperature, duration and pressure.
► According to EN 13060 standard, sterilisers that cannot fit a box with dimensions of 30x30x60cm and below 60 litres are small sterilisers.
►According to EN 285 standard, sterilisers with a boiler that can accommodate a box at least 30x30x60cm in size are defined as large sterilisers. 
 
 
Steam Sterilisation Application Temperatures and Times:
 
 3 - 3,5 minutes at 134 °C (in pre-cleaned autoclaves)
 15 minutes at 121 °C (in pre-cleaned autoclaves)
 30-45 minutes at 121 °C (in autoclaves without vacuum)
 
Gravity autoclaves
 Steam enters the steriliser and is replaced by air
 Suitable for materials with no lumen.
 Can be used for sterilisation of liquids.
 Not used for sterilisation of surgical instruments in MSUs
 The Bowie & Dick test is not applicable.
  
Pre-vacuum autoclaves
 
After preheating, the air is removed from the steriliser by vacuum and then the steam fills the steriliser in a series of waves.
 For effective steam sterilisation, the steriliser must be completely free of air and non-condensable gases.
 Ensure that there is no superheated steam with water particles (wet steam).
 This ensures better penetration of the vapour. 
 

Sterilization with Ethylene Oxide (EO)

 
 Ethylene oxide is a colourless, odourless, slightly heavier than air, flammable and explosive, toxic gas. Ethylene oxide works as a sterilant by reacting with the cell wall of microorganisms, causing irreversible alkalisation.
 It is compatible with many medical materials and is the preferred method for temperature sensitive materials. - Ethylene oxide (EtO) sterilisation is a low temperature, humidity and ethylene oxide gas sterilisation process.
 For EtO sterilisation, time, humidity (40-60%) and temperature (37-550 C) must be at certain levels.
 Since EtO gas penetrates easily, ventilation is required at the end of sterilisation in order to remove gas residues on sterile materials.
 The exposure limit is 1 ppm within 8 hours working time in work areas. Short-term (less than 15 minutes) exposure limit is 5 ppm according to OSHA standard
The perceptible rate is approximately 500-750ppm.
 
Advantages
 Preferred for temperature sensitive materials
 No lumen limitation.
 
 Disadvantages                                                                                                     
 Long sterilisation and ventilation time
 Toxic
 Carcinogenic
 Flammable
 Explosive
 Harmful to the environment
 Liquids cannot be sterilised.
 
 Sterilization with formaldehyde

 
LTSF (Low temparature steam and formaldehyde),
Pure formaldehyde is a colourless, flammable, toxic and highly soluble in water, boiling at 19o C. For formaldehyde sterilisation, the temperature should be 50-80 0 C and the humidity should be 60-80%.
As with EtO, people using formaldehyde sterilisers should have regular health checks.
The exposure limit is 0.75 ppm within 8 hours working time in working areas. According to OSHA standard, short-term (less than 15 minutes) exposure limit is 2 ppm.
 
Advantages
Preferred for temperature sensitive materials
No ventilation required
 
Disadvantages
 Toxic
 Carcinogenic
 Liquids cannot be sterilised.
 1.5 CM length, 2 mm inner diameter limitation is available.
  Harm to the environment as formaldehyde is discharged into the drainage system through the water channel
(there is information that it does not harm because it dissolves in water)  
 
 
 
Gas Plasma (H2O2) Sterilization

► Hydrogen peroxide is injected into the device with a cassette inserted by the user. Under deep vacuum, the hydrogen peroxide vaporises and diffuses. During the diffusion phase, hydrogen peroxide, a biocide, has a lethal effect on microorganisms. Radio frequency (RF) energy is then applied to create a plasma that reacts with the microorganisms and stops their vital functions. When the RF energy is switched off, the H2O2 is mainly converted into water vapour and oxygen.
There are no special ventilation requirements.
The H2O2 System completes a sterilisation cycle in approximately 1 hour
Synthetic materials such as cellulose-free polypropylene, tyvek are used for packaging.
► Recommendations of the company are taken for the suitability of lumen diameters and lumen length measurements.
► If the lumen length and diameter are longer than recommended by the company (longer than 40 cm and lumen diameter less than 3 mm), sterilisation is performed using booster.
 
 
Advantages
Sterilisation between 28 minutes and 74 minutes
No ventilation time required
Suitable for temperature and humidity sensitive materials
 No harm to the environment.

Disadvantages
✓Liquids cannot be sterilised
 
 
 Sterilization with Radiation (Irradiation)

 
There are two types of radiation effective on microorganisms; ionising and non-ionising. Gamma rays, high-energy electrons (e-beams) and X-rays belong to the ionising radiation group, while UV rays (240 - 280 nm) are non-ionising radiation types. While ionising radiation types are used for sterilisation purposes, UV rays are mostly used for disinfection purposes due to their large wavelength and therefore low energy level.
 
Radiation has 2 types of effects on microorganisms, direct and indirect. The first is direct DNA damage, the other is the formation of free radicals by secondary reactions in the environment and the inactivation of microorganisms by these radicals. The use of gamma rays for sterilisation is more common due to their high penetrating properties. The source of gamma rays is the imbalance in the number of protons and neutrons in atomic nuclei. The nucleus with excess energy emits electromagnetic radiation called gamma rays. Ionisation is an event that occurs when matter interacts with radiation.
 
Since gamma rays have the ability to pass through the packaging material, they allow sterilisation of end products. It is also a fast, effective and reliable method that can be easily applied on heat sensitive products that cannot be sterilised by conventional techniques such as steam sterilisation.
 
 
For related products, you can access the details of the products by clicking on the links below.
 
➛https://www.sudemed.com/en/product/sterilization-reel​ 
 
➛https://www.sudemed.com/en/product/sterilization-pouch
 
➛https://www.sudemed.com/en/product/sterilization-reel-made-of-dupont-tyvek
 
➛https://www.sudemed.com/en/product/sterilization-pouch-made-of-dupont-tyvek