Ethylene oxide has been used as a low-temperature sterilizing agent since the 1950s, and is still the predominant method of low-temperature sterilization for heat- and humidity-intolerant medical instruments and articles in U.S. medical facilities. There are currently two types of ethylene oxide sterilizing agents: ethylene oxide and freon gas mixtures and 100% pure ethylene oxide gas. The most important characteristics of ethylene oxide as a sterilizing agent are its high efficiency, its penetration of complex items and its broad compatibility with sterilized items. In addition, the monitoring system of ethylene oxide is relatively complete, and there is a special international standard ISO 11138-2 to provide assurance.
Physical Properties of Ethylene Oxide:
Boiling Point:10.7°C
Vapor Pressure 600 mm Hg
Minimum Flammability Concentration 3% (30,000 ppm)
Vapor Density 1.49 (air = 1)
Olfactory Concentration ~ 500-700 ppm
Sterilization Method Development History:
Used since 1950
Used on items sensitive to moisture and heat
There are two types of sterilization systems: mixed gas and 100% EO
Technical Method Characteristics:
Ethylene Oxide (EO) is stable, requires extended venting to remove residual EO, slow item turnover
Toxicity is a concern. Full attention
To the staff: working environment concentration control -- the whole process of negative pressure
To the user: residual in the package -- 8 ~ 12h automatic mechanical ventilation
To the patient: sterilized articles residual --8 to 12h Automatic mechanical ventilation
To the environment: Emission control - natural decomposition, installation in accordance with AAMI ST 41
Advantages:
High penetration No limitation of lumen length, shape and size. Limitations
Can sterilize complex structures
Can penetrate existing packaging materials
Sterilization mechanism is an alkylation reaction
No corrosion of instruments
Compatible with existing methods of sterilizing instruments
Inexpensive
Low cost of the machine
Low cost of daily use
High loading rate
Low cost of the machine
Low cost of daily use
Low cost of the machine
High loading rate
High loading rateNo infrastructure requirements
Wide range of packaging materials available
Complete monitoring tools, the fastest biomonitoring 4h
Decades of experience
Almost all medical supplies can be sterilized
Commonly used medical supplies sterilized by EO:
Rigid and flexible scopes: arthroscope tracheoscopes, cystoscopes, gastroscopes, enteroscopes, mediastinoscopes, fundoscopes, otoscopes, pharyngoscopes, proctoscopes, prostatectomies, thoracoscopes, urethroscopes
Equipment: anesthesia equipment, artificial kidneys, electrical cables, meters, heart-lung machines, respiratory therapy equipment, hemodialysis
Instrumentation: electric drills, burner pens, electrocautery pens, dental drills, microsurgery instruments, neurostimulators, manometers, surgery instruments, bone drills, needles, artificial joints
Rubber products: catheters, dilators, endotracheal tubes, surgical gloves, sheets
Plastic products: airway tubes, dilators, endotracheal tubes, gloves, pacemakers, heart valves, nebulizers, petri dishes, syringes, artificial crystals
Other products: books, toys, linear probes, probes, thermometers, sutures
To protect the operator, we recommend that you use a book, a toy or a thermometer. p>
Safeguard the safety of operators
1, the whole process of negative pressure sterilization, there will be no leakage of EO, to avoid the operator contact with EO.
2, the whole process of leakage monitoring system, once the monitoring of leakage occurs, it will be immediately transferred to the mandatory exhaust program.
3, door lock interlocking insurance device
4, contained in a small dose of independent EO gas tank
Safeguard the safety of sterilized items to the patient
1, take a continuous pulse of forced ventilation exhaust, up to 8-12 hours.
2, at present, most of the hospitals need to be sterilized disposable items are sterilized with ethylene oxide sterilization (including the production of plasma manufacturers, Johnson & Johnson is a superb ethylene oxide)
Safeguard the environment
1, to take the atmospheric emissions, EO first hydrolyzed to ethylene glycol, half-life of about 9-14 days, ethylene glycol is easy to biodegrade to water and CO, so EO is harmless to the environment. So EO is harmless to the environment.
2, medical emissions are very low per <100g
3, EO rapid decomposer, rapid decomposition of EO into water, CO?, heat
Why is the sterilization cycle of ethylene oxide long?
1, ethylene oxide sterilization cycle is divided into preparation stage, EO exposure stage, exhaust stage, total cycle 15 hours, of which ethylene oxide exposure time is only 1 hour.
2, Ethylene Oxide is very penetrating, in order to ensure the safety of patient use, it requires 8-12 hours of mandatory exhaust to exhaust the residual EO in the package.
3, the stability of ethylene oxide is very good, unlike H?O?, will not decay in the sterilization process Hydrogen peroxide plasma is a new low-temperature sterilization technology began to emerge in the 1990s. Plasma is considered to be the fourth state in addition to liquid, gas, and solid, and is formed when gas molecules are excited in an extreme vacuum chamber. Hydrogen peroxide plasma sterilization has the advantage of a short sterilization cycle time and low toxicity of completely decomposed end products . However, due to the consideration of Mycobacteria tuberculosis contamination problems, the U.S. FDA has not approved the use of diffusion enhancer (diffusion enhancer) to solve the problem of hydrogen peroxide vapor penetration of long and narrow lumen items difficult.
Hydrogen peroxide plasma gas
-Sterrad Sterilization System, J&J
-approved by the FDA in October 1996
Advantages:
Fast sterilization
H?O? breaks down readily, no outgassing time, fast turnaround of items
Final decomposition products are non-toxic. (Theoretically)
No installation requirements, no ventilation ducts
Disadvantages:
poor penetration, there are instruments have a strict length of the lumen, the size of the lumen of the limitations of the sterilization mechanism
for the oxidation reaction, there are strict limitations on the material of the instrument
expensive
sterilization of instruments absolutely dry, can not be oiled
Toxicity of hydrogen peroxide and the harmful effects of ultraviolet light generated during the plasma process
Items that cannot be sterilized by plasma:
Any device with dead endlumens
Any device with dead endlumens
Items made of fibrous materials (e.g., cotton, paper, gauze, etc.) Cellulose based materials (i.e. cotton, paper, gauze)
Liquids Liquids
Items that do not meet thelumen/length criteria
Any organizing trays that contain cellulose based materials.
Cloth pads Count sheets (unless Tyvek/plastic)
Traditional adhesive labels Traditional adhesive labels (i.e. Dust Cover labels)
Any device containing a copper metal lumen or a copper alloy lumen (e.g., monel copper-nickel alloy)
Any device or instrument that has not been completely dried out
Any device with a blind-end lumen
Any device with a blind-end lumen
Any device with a blind-end lumen
Any device with a blind end.
Sterilization of any liquid;
Any oil, any powder;
Any liquid-absorbent or liquid-absorbent instrument or device;
Any instrument or device made of vegetable fibrous materials, such as cotton, cloth, paper, carbon, fibre, gauze, cotton wool, etc., and any article containing wood pulp material (cellulose);
Paper-based device catalog sheets or date labels;
Disposable devices, disposable medical supplies that are not recommended by the manufacturer for repeated sterilization;
Implants (unless the manufacturer explicitly recommends the use of the Sterrad® Sterilization System);
Any nylon or nylon-origin material-embedded surfaces.
Any instrument or device that cannot withstand the vacuum process, and any item that is marked for sterilization using only a vented pressure steam sterilizer;
Any instrument or device that may have surfaces that may collapse, resulting in a tight fit against each other, unless there is a special method to avoid this;
Any instrument or device that has an internal component, such as a closed bearing;
Any instrument or device with lumen data within the lumen limitations;
Item material limitations
Only items made of materials that meet the requirements for plasma sterilization may be sterilized using this method
Only instruments approved by the instrument manufacturer may be sterilized using plasma sterilization
Expensive
Machine cost
Warranty and machine-related warranties
All warranty claims are subject to change. p>Prices of warranty parts associated with the machine
Costs of daily use include the cost of monitoring the cartridge packaging material
Specialized instruments
Tyvek bags (very expensive and few suppliers)
Nonwoven fabrics made of polypropylene
Formaldehyde gas sterilization
Formaldehyde is effective against all microorganisms, and it is reliable. Formaldehyde gas has a killing effect on all microorganisms, its sterilization effect is reliable, easy to use, and basically no damage to the disinfected and sterilized items. Formaldehyde natural diffusion ability is one of its shortcomings, especially formaldehyde has a carcinogenic effect. Low-temperature formaldehyde steam sterilizer to solve these shortcomings, can be used for non-heat-resistant and moisture-resistant items of sterilization. The corresponding international standard for biomonitoring of low-temperature formaldehyde steam sterilization is ISO 11138-5.
Formaldehyde fumigation
High and low-temperature steam formaldehyde sterilization
Low-temperature steam formaldehyde:
Formaldehyde gas (CH?O) (2 - 5 %) + low-temperature steam (50 - 80 ° C)
In A few Nordic countries, such as Germany, Sweden, Norway, Finland, etc.
In other European countries not as the main low-temperature sterilization method
In the United States only as a high level of disinfection
Nearly 25 years of development history
And water steam mixed with sterilization is more effective
Sterilization temperature of 60-80 ℃, 60 ℃ sterilization effect is poor
Advantages:
Can be used in combination with autoclave
Basically non-corrosive, equivalent to EO, but need to pay attention to the purity of formaldehyde
Residuals are relatively small, but still need a long time to rinse to remove
Circulation time is relatively small, about 7-8 hours
Low cost of gas
Disadvantages:
Limited penetration Limited penetration (1/60 of ethylene oxide)
Toxicity Highly toxic (formaldehyde is a highly toxic substance, and is highly ranked on the priority control list of toxic chemicals in our country). (Formaldehyde is a highly toxic substance, in China's priority control list of toxic chemicals, formaldehyde ranked second)
Process control issues
Para-formaldehyde residual Since 1962 Pepper et al, in the double aldehyde compounds, found that glutaraldehyde has a significant effect. Since Pepper et al. discovered in 1962 that glutaraldehyde has obvious germicidal activity among double aldehyde compounds, many scientists have carried out extensive and in-depth research on its physicochemical properties, bactericidal activity, clinical application and toxicity, and its discovery and application are called the third milestone in the history of chemical disinfectant development. In clinical use, glutaraldehyde has the advantages of wide bactericidal spectrum, high efficiency, weak corrosiveness, good stability, etc., and low price, easy to obtain, and has been widely used in medical equipment, endoscopy, respiratory therapy equipment, dialysis equipment, anesthesia equipment, etc. disinfection and sterilization.
Studies have found that the activity of glutaraldehyde disinfectants is easily affected by pH value, temperature, formulation type, placement time, concentration dilution, cross-linking reaction of glutaraldehyde itself, and special insensitive pathogens, which is noteworthy in clinical use. Because of the concentration of glutaraldehyde < 1% when many pathogenic bacteria will produce drug resistance, so in clinical use, the common concentration of 2%. However, due to the use of many factors, such as humid instruments in the use of dilution and other effects, daily monitoring of the concentration of glutaraldehyde before use in accordance with the relevant national standards is also very necessary. The adverse effects of glutaraldehyde, the fact that it can only be used for immersible instruments, and the long time required for sterilization are all reasons for restricting the use of glutaraldehyde. 2% glutaraldehyde solution has obvious irritating effects on human skin and mucous membranes, and is more irritating to the eyes and the upper respiratory tract, and the time-weighted average of the acceptable exposure concentration (TWA) is 0.05 ppm, and there are cases of allergic reactions and systemic adverse effects. There are cases of allergic reactions and systemic adverse reactions. Personal protection, especially for eyes and respiratory tract, should be strengthened in clinical use, e.g., eye protection against splashes, good indoor ventilation. Due to the occupational safety factors of glutaraldehyde, the use of glutaraldehyde is prohibited in some European countries, and clinical use of ophthalaldehyde (OPA) and peroxyacetic acid (PAA) is gradually emerging as a substitute.