3 Phút Khám Phá Ưu Và Nhược Điểm Giữa Phương Pháp Tiệt Trùng Khô Và Tiệt Trùng Hơi Nước

Dry Sterilization

1. What is Dry Heat Sterilization?

   • Dry sterilization is the first method of sterilization applied, using hot air to kill or eliminate all microorganisms and bacterial spores. This method requires a longer exposure time (1.5-3 hours) combined with high temperatures. It is used to sterilize items that may be damaged by moist heat (e.g., powders, petroleum products, sharp instruments).

   • Dry heat sterilization occurs through heat conduction. Initially, the heat is absorbed by the outer surface of the product, then conducted inward through layers until the entire product reaches the necessary temperature, at which point sterilization begins. Dry heat destroys cellular components through oxidation, killing the bacteria. Spores, which are more resistant, require longer exposure times.

   The most common temperature-time parameters for sterilization using hot air sterilizers are:

   • 170°C (340°F) for 30 minutes,

   • 160°C (320°F) for 60 minutes.

   Bacillus atrophaeus spores should be monitored during dry heat sterilization because they are more resistant to dry heat than Geobacillus stearothermophilus spores.

2. Advantages of Dry Heat Sterilization

   • Dry heat sterilizers are easy to install and relatively low in operational costs.

   • It can penetrate materials.

   • It is non-toxic and environmentally friendly.

   • It does not corrode metal and sharp instruments.

3. Disadvantages of Dry Heat Sterilization

   • This method is time-consuming because the rate of heat penetration and bacterial killing is slow.

   • The high sterilization temperatures are unsuitable for many materials, e.g., plastic and rubber items cannot be sterilized by dry heat because the temperatures used (160–170°C) are too high for these materials.

   • The time and temperature needed vary for different substances, and overexposure can damage some substances.

Steam Sterilization

1. What is Steam Sterilization?

   Of all the methods for sterilization (killing or eliminating all microorganisms, including bacterial spores), moist heat in the form of saturated steam under pressure is the most widely used and effective method. Steam sterilization is non-toxic, inexpensive, and quickly kills bacteria. It rapidly heats and penetrates materials.

   Moist heat kills bacteria by irreversible denaturation of enzymes and structural proteins. The temperature at which denaturation occurs inversely varies with water content. Sterilization occurs in saturated steam, requiring precise control of time, temperature, and pressure.

   Pressure acts as a means to achieve the high temperatures necessary to rapidly kill microorganisms. A specific temperature must be reached to ensure complete microbial elimination. The minimum sterilization time should be measured from the point when all materials to be sterilized have reached the required temperature.

   The optimal time for autoclave sterilization is 15 minutes at 121°C (200 kPa). Temperature should be controlled and monitored throughout the process; pressure is primarily used to achieve the desired steam temperature.

   In certain cases (e.g., heat-sensitive materials), sterilization can be performed at temperatures below 121°C, provided the appropriate combination of time and temperature is applied.

2. Advantages of Steam Sterilization

   • Non-toxic to patients, healthcare workers, and the environment.

   • Cycles are easy to control and monitor.

   • Rapid bacterial killing.

   • Less affected by organic/inorganic matter during sterilization.

   • Fast cycle times.

   • Penetrates medical packaging.

3. Disadvantages of Steam Sterilization

   • Harmful to heat-sensitive instruments.

   • Repeated exposure can damage micro-surgical instruments.

   • May leave instruments wet, causing them to rust.

   • Can cause burns.

   • 150°C (300°F) for 150 minutes or longer, depending on the volume.

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