Gas method of sterilization

Gas sterilization is used for sterilization of objects that cannot be subjected to heat treatment (Fig. 9).

Figure 9.

Gas sterilizer

These are surgical instruments having a mirror surface, optical and radio electronic equipment, cutting and piercing instruments with micron sharpening, catgut, disposable items and various products from heat-nonresistant synthetic plastics (probes, catheters and others), nonresistant to steam, air and chemical (with solutions) sterilization. Sometimes gas sterilization is used to sterilize some heat-resistant subjects.

At gas sterilization are used:

· A mixture of ethylene oxide and methyl methane. Sterilization is carried out in a pack of two layers of polyethylene film of a thickness of 0.06 to 0.2 mm, parchment, paper bag waterproof. The gas dose is 2000 mg/dm3, exposure time is 240 hours. Shelf life of products sterilized in plastic packaging is up to five years, Kraft-paper is 20 days.

· Sterilization by steams of 16% formalin is used for disinfection of optics, pacemakers, glass, metal, products of polymer materials. Sterilizer is filled by packed sterilized objects to 2/3 of its volume. From a cardboard case remove the vial containing gas through a plastic bag, not disturbing its entireness, unscrew the stopper, the contents of the bottle pour into a polyethylene bag and place it on top of the sterilized objects. Close the sterilizer by lid, squeeze it tightly with screws. After sealing of apparatus mark the beginning of the exposure.

· Products, sterilized by gas method may be applied only after a thorough airing in a ventilated room. Metal and glass objects should be ventilated for at least one day, rubber and polymer materials for 5 days, the objects having a long (over 30 min) contact with the wound surface for 14 days, products used for children for 21 days.

Chamber gas sterilization due to the high toxicity to humans is rare used.

4.7 Methods for quality control of sterilization:

· Technical

· Chemical

· Bacteriological

Technical method. The use of pressure gauges, thermometers, gauges, etc. allows you to monitor the temperature, pressure, steam or gas sterilization, time of exposure and other parameters.

Chemical control method of sterilization is carried out routinely. It is based on the property of some substances to melt or change color under the influence of a certain temperature. As indicators can be applied benzoic acid (t° 122,36°), urea (132,7°), thiourea (187-182°), ascorbic acid (187-192°) and other.

Bacteriological control method is the most specific and accurate. In the sterilizer put the bottle with live test organisms or bacteriological tests in paper bags that lose their viability after completion of the sterilization cycle, in particular for these microorganisms mode. Then plant these microorganisms in a nutrient environment and determine their viability after sterilization. These methods require time, but they allow you to control effectively the work of the sterilizer in different modes. This method has several disadvantages: it takes time and creating aseptic conditions for transfer of test organism after sterilization in a nutrient environment.

Дата добавления: 2015-10-29