High Quality Autoclave Test Strips

When carrying out sterilization, the most important role is given to the implementation of constant control of its quality using special control methods.
Chemical control method
The chemical method has gained the greatest popularity among other sterilization control methods, primarily due to the availability and ease of use of chemical indicators. It is based on the change in color of the chemical indicator on the test strip after sterilization.
Chemical indicators are used to assess the quality of steam, air, gas and radiation sterilization. It should be noted that in practice, medical institutions and beauty salons prefer the first two methods of sterilization.
In general, their use allows you to evaluate such important parameters:
With air sterilization – maximum temperature, time;
With steam – temperature, time, steam saturation;
With gas – temperature, time, humidity, concentration of a substance (ethylene oxide, formaldehyde).
The essence of the use of chemical control indicators is based on the determination of these critical parameters.

Types of chemical indicators
The use of chemical indicators is an express method that allows you to timely monitor compliance with important sterilization parameters. According to ISO 11140-1-2014, all chemical indicators are divided into 6 classes.
Type 1. “Witnesses” of the process. Process indicators

These chemical indicators react to only one parameter – to reach the maximum temperature in the sterilizer. First class chemists are affixed to the sterilization bag or box to indicate that the instrument package has been sterilized. Thus, the color change of these chemical indicators makes it possible to differentiate the sterilized instrument packaging from the non-sterilized one. However, it is impossible to assess the quality of sterilization with the help of first-class chemical indicators, since another important characteristic is not taken into account – exposure time.

Type 2. Indicators for special tests
The 2 class includes indicators for special tests, which are used, for example, for the Bowie-Dick test. The mentioned test does not in fact evaluate the quality of sterilization. However, it allows you to evaluate the health of the steam sterilizer and in particular the operation of its vacuum system. More specifically, the Bowie-Dick test allows you to evaluate whether the autoclave removes the required amount of air before introducing steam, which ultimately affects the quality of sterilization. For the test, a special sheet of paper with a chemical indicator applied in the form of a figured pattern is used, which reacts to moisture. With proper sterilization, the pattern completely changes color. If the pattern has only partially changed color, this indicates that the autoclave is broken.

Type 3. Single Variable Indicators
The 3 class includes single-variable indicators. As you can understand from the name, with their help it is possible to evaluate only one sterilization parameter. Often the maximum temperature is estimated, but there is no data on the time of its impact. An example is a test strip made of paper with indicator paint applied to it. When the maximum temperature in the sterilizer is reached, the thermal indicator changes color.

Type 4. Multivariable indicators
The 4 class includes multivariable indicators. They are used to control the quality of several parameters of the sterilization cycle – temperature and time. The principle of indicators remains the same: they are paper strips coated with chemical indicator paint. However, the paint does not change color immediately upon reaching the maximum temperature, but after a certain time of exposure. Therefore, test strips are indicated by two numbers, for example, 180/60, which means the standard sterilization parameters in a dry-heat cabinet.

Type 5. Integrating indicators
The 5 class includes integrating indicators. They are designed to respond to all parameters, and therefore their color changes only when all parameters of the sterilization cycle reach the standard values. For example, in an autoclave at 134°C, the color will change only after 3.5 minutes.

In addition, integrating indicators actually correspond to bioindicators. However, unlike biotests, integrating ones give an idea of ​​the quality of sterilization immediately and there is no need for further laboratory testing of biological indicators.

Type 6. Emulator indicators
The 6 class includes indicators-emulators. These are control chemical indicators designed to respond to all parameters under specific sterilization regimes. They are the most accurate and modern chemical indicators.

How to use chemicals?
How often should chemical sterilization indicators be used? This question is often asked by heads of institutions. The answer to this question is very simple – it is necessary to use indicators every time you put instruments into the sterilizer. Only constant quality control of sterilization will allow timely detection of a breakdown of the sterilizer or improper sterilization by an employee, and then promptly solve the problem.

At each laying of instruments, disposable chemical indicators are placed in the autoclave at the control points: in the lower and upper parts of the autoclave, as well as in the center of sterilization boxes (packages) located at different levels.

The required number of chemical indicators is determined based on the size of the autoclave:

With an autoclave volume of up to 100 cm3, chemical indicators are placed at 5 control points;
With a volume of 100-750 cm3 – chemical indicators are placed at 11 control points;
With a volume of more than 750 cm3 – chemical indicators are placed at 13 control points.
Chemical indicators are placed in a dry-heat cabinet at control points according to the envelope type: in the center of the sterilizer, in the lower part of the sterilizer in the corners, in the upper part of the sterilizer in the corners.

When the volume of the oven is up to 80 cm3, the chemical indicators are placed at 5 control points;
If the volume of a single-chamber dry-heat oven is more than 80 cm3, chemical indicators are placed at 15 control points;
When the volume of a two-chamber dry-heat cabinet is more than 80 cm3, chemical indicators are placed at 30 control points.
After the quality control of sterilization, the results are necessarily recorded in the sterilizer’s work log.

Technical Specifications: