Carried out in autoclaves different design. The autoclave is a hermetically sealed vessel consisting of a thick-walled sterilization chamber and a casing.

The autoclave has safety valve, which ensures the release of steam at excess pressure, and a pressure gauge. Each autoclave must have instructions for its operation and maintenance, as well as a boiler supervision passport.

The object to be sterilized is placed inside the steam chamber. The water chamber is subjected to heating. First, the autoclave is heated with the tap open until the steam go strong continuous jet and will not displace the air in the autoclave, which significantly reduces the thermal conductivity of water vapor (with a content of 5% air in water vapor, it decreases by 50%)

During the heating of the autoclave after closing the valve, it is necessary to monitor the pressure, in parallel with the increase of which the temperature of the steam increases.

Autoclaving - most reliable way sterilization. Typically, sterilization in an autoclave is carried out at 119-121 ° C for 8-15 minutes, depending on the volume of the solution. This guarantees a sufficiently complete sterilization, regardless of the type of microorganism. In this way, dishes, paper and glass filters, tools, water solutions resistant to exposure are sterilized. high temperature medicinal substances, dressing material.

In some cases, heating saturated steam in an autoclave at 119-121 ° C, up to 120 minutes are carried out, and if sterilization is carried out at 110 ° C, then its duration is 30-60 minutes.

Sterilization with fluid steam is carried out in a Koch fluid steam apparatus or in an autoclave with an unscrewed lid and an open outlet cock. The Koch apparatus is a metal hollow cylinder with a double bottom. The space between the upper and lower bottom plates is filled 2/3 with water (there is a tap to drain the water remaining after sterilization). The lid of the apparatus has a hole in the center for a thermometer and several small holes for steam to escape. The material to be sterilized is loaded loosely into the chamber of the apparatus in order to provide the possibility of its greatest contact with steam. The beginning of sterilization is the time from the moment the water boils and steam enters the sterilization chamber. In a fluid steam apparatus, mainly nutrient media are sterilized, the properties of which change at temperatures above 100°C. Sterilization with flowing steam should be repeated, since a single heating at a temperature of 100 ° C does not provide complete disinfection. This method is called fractional sterilization: the treatment of the sterilized material with flowing steam is carried out for 30 minutes daily for 3 days. Between sterilizations, the material is kept at room temperature for the germination of spores into vegetative forms, which die during subsequent heating.

Tyndalization.

Tyndalization is fractional sterilization using temperatures below 100°C, proposed by Tyndall. The heating of the material to be sterilized is carried out in a water bath equipped with a thermostat for an hour at a temperature of 60-65°C for 5 days or at 70-80°C for 3 days. Between heatings, the processed material is kept at a temperature of 25°C for spores to germinate into vegetative forms, which die during subsequent heatings. Tyndallization is used to dehydrate nutrient media containing protein.

Mechanical sterilization with bacterial ultrafilters. Bacterial filters are used to free the liquid from the bacteria in it, as well as to separate bacteria from viruses, phages and exotoxins. Viruses are not retained by bacterial filters, and therefore ultrafiltration cannot be considered as sterilization in the accepted sense of the word. For the manufacture of ultrafilters, finely porous materials (kaolin, asbestos, nitrocellulose, etc.) are used that can trap bacteria.

Asbestos filters (Seitz filters) are asbestos plates 3-5 mm thick and 35 and 140 mm in diameter for filtering small and large volumes liquids. In our country, asbestos filters are produced in two grades: “F” (filtering), retaining suspended particles, but passing bacteria, and “SF” (sterilizing), denser, retaining bacteria. Before use, asbestos filters are mounted in filter apparatuses and sterilized together with them in an autoclave. Asbestos filters are used once. Membrane ultrafilters are made of nitrocellulose and are disks white color 35 mm in diameter and 0.1 mm thick.

Bacterial filters differ in pore size and are designated by serial numbers (Table 2).

Membrane filters are sterilized by boiling immediately before use. The filters are placed in distilled water heated to a temperature of 50-60°C to prevent their twisting, boiled over low heat for 30 minutes, changing the water 2-3 times. Sterilized filters are removed from the sterilizer with flambéed and cooled tweezers with smooth tips to avoid damage.

To filter liquids, bacterial filters are mounted in special filter devices, in particular, in the Seitz filter.

It consists of 2 parts: the upper, shaped like a cylinder or funnel, and the lower supporting part of the apparatus, with the so-called filter table made of metal mesh or a clean ceramic plate on which a membrane or asbestos filter is placed. The supporting part of the apparatus has the shape of a funnel, the tapering part of which is located in the rubber stopper of the neck of the Bunsen flask. In working order upper part the device is fixed on the bottom with screws. Before starting connection filtering various parts installations to create tightness are filled with paraffin. The outlet tube of the flask is attached to a thick-walled rubber tube to a water jet, oil or bicycle pump. After that, the filtered liquid is poured into the cylinder or funnel of the apparatus and the pump is turned on, creating a vacuum in the receiving vessel. As a result of the resulting pressure difference, the filtered liquid passes through the pores of the filter into the receiver. Microorganisms remain on the filter surface.

The advantage of the method is the rapid and uniform heating of the entire volume of the sterilized chamber, since the density and thermal conductivity of steam are equal to those for water. Therefore, the duration and temperature of sterilization with steam is lower than with heated air.

Table 3.8, b. Air sterilization method (dry hot air)

Steam sterilization with saturated steam is carried out in 2 modes:

At overpressure: 0.11 + 0.02 MPa (1.11 + 0.2 kgf / cm 2) - temperature (120 + 2) degrees C;

At overpressure: 0.2 + 0.02 MPa (2.2 + 0.2 kgf / cm 2) - temperature (132 + 2) degrees C.

Steam sterilization at a temperature of (132 + 2) degrees C is recommended for solutions of thermostable medicinal substances (Table 3.10).

Table 3.9. Sterilization exposure time depending on the volume of the solution

Table EVIL. Steam method (pressurized water saturated steam)

Control temperature regime steam sterilization carried out with a maximum thermometer with a scale of 210 degrees C or thermocouples. As a chemical thermal test, a mixture of benzoic acid with fuchsin (10:1) is used, the melting point is 121 degrees C.

Steam sterilization under pressure is carried out in steam sterilizers various designs(Fig. 3.22, 3.23). In terms of shape, pressure steam sterilizers are divided into cylindrical (circular, letter K in the designation) and rectangular (letter P). Cylindrical can be located horizontally and vertically (letters GiV, respectively). An example of the designation of sterilizers:

VK - vertical circular electric;

GP - horizontal rectangular electric unilateral;

GPA - horizontal rectangular electric double-sided.

The numbers indicate the diameter of the sterilization chamber. The sterilizer consists of 3 cylinders. The first (outer) cylinder is called the casing. It protects the steam boiler of the sterilizer from possible mechanical damage, and service staff- from burns.

Rice. 3.23. Steam sterilizer VK-75

Rice. 3.22. Steam sterilizer GP-400

The second (middle) cylinder is the main part of the sterilizer, called the steam chamber. It is made of high quality steel and is designed to produce steam from water.

The third (inner) cylinder is called the sterilization chamber. Its purpose is to contain the material to be sterilized, protecting it from water. In the upper part of the sterilization chamber there are openings for the passage of steam into it. In addition, they serve as a separator, separating steam from water droplets so that the material to be sterilized is not moistened (steam captures water particles). Lid with rubber gasket and the central shutter serves to tightly close the water vapor chamber. The material to be sterilized is loaded through the same cover. Steam enters the sterilization chamber from a kettle (or from a water-steam chamber), which has an electric heating element inside. The water-steam chamber is filled with purified water through a funnel. Filling is monitored by the water gauge glass.

The pressure sterilizers are equipped with an electrocontact pressure gauge, a vacuum pressure gauge, a water jet ejector, a pump and a safety valve. The electrocontact manometer provides automatic maintenance of the set pressure.

The vacuum gauge is used to control the pressure in the sterilization chamber. With the help of a water-jet ejector, rapid steam extraction is achieved after each sterilization, a vacuum is created in the sterilization chamber and the materials being sterilized are dried, which is especially important when sterilizing paper, cotton wool, etc. The safety valve serves to protect the sterilizer from an excessive increase in steam pressure in it.

The most convenient are desktop steam sterilizers (Fig. 3.24), in which the set pressure and temperature are automatically maintained, and it is also possible to dry the auxiliary material after sterilization (cotton wool, filter paper, gauze, etc.). To remove air from the chamber, quick drying material after sterilization has a built-in vacuum pump.

The sterilizer has a liquid crystal display with a touch keyboard that allows you to select:

3 sterilization programs for packed and open instruments at 134 degrees C;

Rice. 3.24. Semi-automatic steam sterilizer

2 sterilization programs for packed and open instruments at 121 degrees C;

program with customizable parameters;

Fast cycle (134 degrees C - 4 minutes, total time - 14 minutes).

Boiling

This method sterilizes rubber items, surgical instruments, glassware. It is not recommended to use boiling for sterilization of injection solutions, since in terms of efficiency it is significantly inferior to steam sterilization.

Steam Sterilization

You call fluid "saturated water vapor (without admixture of air), having a pressure of 760 mm Hg. Art. and a temperature of 100 °C. Sterilization with flowing steam is carried out in a steam sterilizer or autoclave at 100 ° C for 30--60 minutes, depending on the volume of the solution. This is one of the common methods for sterilizing injectable solutions in pharmacies.

Steam sterilization under pressure (autoclaving)

It is carried out in autoclaves of various designs. An autoclave is a hermetically sealed vessel consisting of a thick-walled sterilization chamber and a casing (Fig. 36). The autoclave has a safety valve that allows steam to escape at excess pressure, and a pressure gauge. Each autoclave must have instructions for its operation and maintenance, as well as a boiler supervision passport.

The object to be sterilized is placed inside the steam chamber. The water chamber is subjected to heating. First, the autoclave is heated with the tap open until the steam flows in a strong continuous stream and displaces the air in the autoclave, which significantly reduces the thermal conductivity of water vapor (with a 5% air content in water vapor, it decreases by 50%).

During the heating of the autoclave after closing the valve, it is necessary to monitor the pressure, in parallel with the increase of which the temperature of the steam increases. The relationship between temperature and vapor pressure is expressed as follows:

1atm100 °С1.5 "112.7 °С" 119.6 °С "132.9" С 5 "151.1 "С

Autoclaving is the most reliable method of sterilization. Usually sterilization in an autoclave is carried out at 119 - 121 ° C for 8 - 15 minutes, depending on the volume of the solution. This guarantees a sufficiently complete sterilization, regardless of the type of microorganism. In this way, dishes, paper and glass filters, instruments, aqueous solutions of high-temperature-resistant medicinal substances, dressings are sterilized.