42 Explain how the autoclave and hot-air sterilizing oven kill micro and why……

Sterilization is a very important part of the health industry as well as the research oriented laboratories attached to medical care, bio-technology and various other fields. However sterilization is not as simple as it sounds and requires proper care and technology to achieve. Hot air sterilization ovens are designed for the purpose of proper sterilization and are widely used in the health care industry.

The application of sterilization techniques is highly critical for medical instruments, devices, consumable as well as implantable devices. There are many methods of sterilization and proper care needs to be taken while selecting the right technique for the right application. Sterilization can be achieved by using various methods like application of chemicals, heat, irradiation, filtration and even high pressure. Coming to heat sterilization, there are two methods used: Moist heat sterilization and, Dry heat sterilization.

Moist heat sterilization

Moist heat as the name indicates uses extreme heat to sterilize instruments or devices exposed to it by using hot air which is heavily laden with moisture. The moisture in the air used plays a pivotal role in achieving sterilization. There are various methods and processes used to achieve moist heat sterilization as follows:Pasteurization (as in milk),Boiling the devices/instruments,Steam sterilizer,Water bath (hot) and Autoclave . When this form of sterilization is to be used, the most preferred method in the health industry is the Autoclave.

Dry heat sterilization

Dry heat sterilization is the oldest process of sterilization used by mankind. This method involves blowing hot air over the devices or instruments to be sterilized. The hot air blown has none or very little moisture in it and it plays almost no role in the process of sterilization. There are many methods of dry heat sterilization used as follows: Incineration (burning),Radiation, Flamming, Hot air ovens,Microwave ovens,Radiation. The most favored form of dry heat sterilization used by the health care industry is the hot air oven. Now that we have understood the technicalities of heat based sterilization, let us take a look at the advantages and disadvantages of using the hot air oven and autoclaves that are preferred by the health care industry.

Autoclaves – Advantages and Disadvantages

Autoclaves are known to be used to sterilize materials that can withstand very high temperatures. An autoclave also produces a very high pressure due to which materials like glass and powders may break, disintegrate or even get burnt. This disadvantage of autoclave also means that consumables and surgical materials like bandages or cotton cannot be sterilized using it. However, the advantage of an autoclave for the materials that can take the heat and pressure is that the moist heat produced helps coagulate proteins in micro-organisms and kill them completely. If the temperature is high enough, it can also kill prions due to the radical damage (oxidative-free) it can cause.

Hot air ovens – Advantages and Disadvantages

Moisture is almost negligible while using a hot air oven and the pressure built up inside is much lesser compared to an autoclave. In addition to being safer than autoclaves, hot air ovens are much smaller in size and have an almost equal effectiveness when it comes to sterilization. Temperatures can reach very high levels as in an autoclave and being non-moist; they can sterilize a wider variety of devices and instruments safely. However, the only disadvantage is that a few tough micro-organisms like prions may not be killed in a hot air oven all the time.

Now, it is not so difficult to infer why hot air ovens are preferred over autoclaves by most laboratories and health care facilities.