Ethylene oxide gas has strong bactericidal power and broad bactericidal spectrum, and can kill various microorganisms, including bacterial spores. It is a disinfectant. Because ethylene oxide is flammable and explosive, it is toxic to people, so it must be carried out in a closed ethylene oxide sterilizer.
(1) ethylene oxide sterilizer and its application;
1) There are many kinds of ethylene oxide sterilizers currently in use, ranging from tens of cubic meters for large containers, to 1 ~1cubic meters for medium containers and to1cubic meters for small containers. They have different uses.
Large-scale ethylene oxide sterilizer: generally used to sterilize a large number of articles, the dosage is 0.8 kg/m ~ 1.2 kg/m, and it works at 55℃ ~ 60℃ for 6 hours.
3) Medium-sized ethylene oxide sterilizer: generally used for sterilization of disposable medical supplies. This kind of sterilization equipment is perfect and has a high degree of automation. It can use pure ethylene oxide or mixed gas of ethylene oxide and carbon dioxide. The general sterilization conditions are: the concentration is 800 mg/L ~ 1000 mg/L, the temperature is 55℃ ~ 60℃, the relative humidity is 60% ~ 80%, and the action time is 6 h. After sterilization, vacuum is needed. Sterile articles are usually packed in a sealed plastic film that is permeable to ethylene oxide. If the packet is equipped with a filter membrane that can filter air, the sterilization effect will be better.
4) Small ethylene oxide sterilizers are mostly used in medical and health departments to handle a small amount of medical instruments and supplies. At present, there is 100% pure ethylene oxide or mixed gas of ethylene oxide and carbon dioxide. This sterilizer has a high degree of automation, which can automatically vacuumize, automatically add medicine, automatically adjust temperature and relative humidity, and automatically control sterilization time.
5) The requirements for small and medium-sized ethylene oxide sterilizers are as follows: it has good pressure resistance and sealing performance, can withstand the water pressure test of 1.25 times the working pressure, is invariant and does not leak, and the vacuum degree can be pumped to above 53.3 kPa; Accurate dosage, good heat preservation performance, and adjustable temperature and relative humidity in the sterilizer; When washing with outside air after disinfection, the input air can pass through a high-efficiency filter, which can filter out ≥ 0.3 & micro; More than 99.6% m particles; After the discharged residual ethylene oxide is treated harmlessly, the residual ethylene oxide in sterilized articles should be less than15.2 mg/m; /m； The concentration of ethylene oxide in sterilization environment should be less than 2 mg/m.
(2) Preparation and packaging of articles before sterilization: The articles to be sterilized must be thoroughly cleaned, and care should be taken not to rinse with normal saline. There should be no water drops or too much water on the sterilized articles to avoid dilution and hydrolysis of ethylene oxide. Ethylene oxide can be used to sterilize almost all medical supplies, but it is not suitable for the sterilization of food, liquid, grease, talcum powder and animal feed. Packaging materials suitable for ethylene oxide sterilization include paper, composite dialysis paper, cloth, non-woven fabric, breathable rigid container, polyethylene and so on. Packaging materials that cannot be used for ethylene oxide sterilization include metal foil, polyvinyl chloride, cellophane, nylon, polyester, polyvinylidene chloride and impermeable polypropylene. Changes in packaging materials should be verified to ensure the reliability of sterilization of sterilized items.
(3) Loading of sterilized articles: the articles loaded in the sterilization cabinet should have gaps on the top, bottom, left and right sides (the sterilized articles should not touch the cabinet wall), and the articles should be placed in metal baskets or metal racks; The loading capacity of articles shall not exceed 80% of the total volume in the cabinet.
(4) sterilization: according to the operating instructions of the manufacturer of ethylene oxide sterilizer; According to different types, packages, loads and methods of sterilized articles, appropriate sterilization parameters are selected.
1) Relationship among concentration, temperature and sterilization time: Within a certain range, sterilization time can be shortened with the increase of temperature and concentration. When ethylene oxide is used for sterilization, the parameters of temperature, concentration and time must be reasonably selected.
2) Control the relative humidity of sterilization environment and the water content of articles: The water content of bacteria and sterilized articles has a significant impact on the sterilization effect of ethylene oxide. In general, the relative humidity is 60% ~ 80%. The water content is too small, which affects the penetration and alkylation of ethylene oxide and reduces its bactericidal ability; Excessive water content will dilute and hydrolyze ethylene oxide, which will also affect the sterilization effect. In order to achieve the ideal humidity level, the first step is to pre-moisten the sterilized materials, which generally requires that the sterilized materials be placed in an environmental condition with a relative humidity of 50% for at least 2 hours; Secondly, the humidifying device can be used to ensure the ideal humidity level in the cabinet.
3) Pay attention to the influence of external protective substances on sterilization effect: the more organic matter on the surface of bacteria, the more difficult it is to kill; Organic matter can not only affect the penetration of ethylene oxide, but also consume a part of ethylene oxide. It is difficult to kill microorganisms in inorganic salts or organic crystals with ethylene oxide. Therefore, before ethylene oxide sterilization, the organic and inorganic pollutants on the articles must be fully cleaned to ensure the success of sterilization. ① The ethylene oxide sterilization procedure should include preheating, pre-wetting, vacuumizing, introducing gasified ethylene oxide to a predetermined concentration, maintaining sterilization time, removing ethylene oxide gas in the sterilization cabinet, and analyzing and removing ethylene oxide residues in sterilized articles.
② 100% pure ethylene oxide or mixed gas of ethylene oxide and carbon dioxide can be used for ethylene oxide sterilization. The use of freon is prohibited.
③ The analysis can be continued in the ethylene oxide sterilization cabinet or put in a special fume hood, and natural ventilation is not allowed. Repeatedly input air should be efficiently filtered, and more than 99.6% of particles ≥0.3um can be filtered.
(4) Ethylene oxide residue mainly refers to ethylene oxide and its two by-products chloroethanol ethane and ethylene glycol ethane which remain in articles and packaging materials after ethylene oxide sterilization; Exposure to excessive ethylene oxide residues can cause burns and inflammation in patients. The residual amount of ethylene oxide is related to the material, sterilization parameters, packaging material and packaging size, loading capacity, analysis parameters and so on. PVC catheter was analyzed for 8 hours at 60℃; At 50℃, the resolution is 12h. Some materials can shorten the analysis time, such as metal and glass can be used immediately, and some materials need to extend the analysis time, such as built-in pacemaker. 5) Ethylene oxide emission: the atmosphere is the first choice for ethylene oxide emission in hospitals. When installing, it is required to have a special exhaust pipe system, and the exhaust pipe material must be impermeable to ethylene oxide, such as copper pipe. There shall be no combustible materials and air inlets of buildings such as doors and windows within 7.6m of the exhaust port; If the length of the vertical part of the exhaust pipe exceeds 3m, a water collector must be installed to prevent the exhaust pipe from drooping or circling, causing water vapor accumulation or freezing in winter and blocking the pipeline; The exhaust pipe should be led to the outside, and the outlet should be reversed downward to prevent water vapor from staying on the pipe wall or blocking the pipe wall; Professional installation engineers must be invited to install according to the requirements of ethylene oxide sterilizer manufacturers. If ethylene oxide is discharged into water, the whole discharge system (pipes, tanks, etc. ) must be sealed, otherwise a lot of ethylene oxide with heat will overflow from the water and pollute the surrounding working environment. (1) Installation requirements of ethylene oxide sterilizer: The ethylene oxide sterilizer must be placed in a well-ventilated place, not near the fire source. In order to facilitate maintenance and regular maintenance, 5 1cm should be reserved on each side (including the top) of the ethylene oxide sterilizer. Special exhaust pipes should be installed and completely isolated from other exhaust pipes in the building.
(2) Safety protection principles and precautions for ethylene oxide:
1) Ensure that the ethylene oxide sterilizer and gas cylinders or gas cylinders are away from fire sources and static electricity.
2) The storage place of ethylene oxide shall be free from fire source, rotating motor, sun exposure and good ventilation, and the temperature shall be lower than 40℃, but it shall not be stored in the refrigerator. Strictly follow the storage requirements of inflammable and explosive articles formulated by the state.
3) Don't use too much force when adding medicine and opening a bottle, so as to avoid the liquid medicine gushing out.
4) Monitor the air concentration of ethylene oxide working environment every year.
5) EO staff should be trained in professional knowledge and emergency handling. After excessive exposure to ethylene oxide, quickly remove the patient from the poisoning site and inhale fresh air immediately; After skin contact, rinse the contact area with water for at least 15min, and take off the dirty clothes at the same time; Eyes exposed to liquid ethylene oxide or high concentration ethylene oxide gas should be rinsed for at least 10 minute. In case of the above situation, you should see a doctor as soon as possible.
6) Regularly clean, maintain and debug the ethylene oxide sterilization equipment according to the requirements of the manufacturer.
7) Ethylene oxide can form toxic ethylene glycol when it meets water, so it cannot be used for food sterilization.