Items are sterilized in a sterilizer. In the medical field, surgical instruments in particular are sterilized to reduce the risk of infection. Physical sterilization is done either by heat, radiation or steam.
What is a sterilizer?
In the medical field, sterilization usually takes place in physical sterilizing autoclaves that use steam. The killing of microorganisms can be done by heating instead of pressure. Medical sterilizers are used for sterility, i.e. sterilization. A sterilizer rids treated surfaces of DNA fragments, viruses and microorganisms of any stage, including their spores. Sterilizers are usually physical sterilizers. Chemical sterilizers work with toxic gases and place high demands on safety precautions. Therefore, they are hardly used. In the medical field, sterilization usually takes place in physically sterilizing autoclaves operated with steam. The microorganisms can be killed by heating instead of pressure. In addition to the medical sector, areas such as biotechnology or the food industry also rely on sterilizers. While surgical instruments and other instruments are mainly sterilized in the medical sector, glassware, for example, is sterilized in the biotechnology sector. The world’s first steam sterilizer was invented by M. Lautenschläger at the end of the 19th century. This invention was a great step for medical sterility. Until the 19th century, little sterile work was done in medicine. The invention of the sterilizer thus reduced the risk of infection, sepsis, and death as a result of medical treatments.
Forms, types and kinds
Medical sterilizers are usually steam sterilizers. These are pressurized vessels that can be sealed gas-tight and in which various materials can be subjected to thermal treatments in a positive pressure environment. Most often, sterilization is initiated by a vacuum process. In this process, the container is pumped empty several times and steam flows in. In the gravitational process, on the other hand, the air in the steam sterilizer is displaced by saturated steam. Medical steam sterilization takes place at temperatures of 121 degrees Celsius and an overpressure of one bar. The materials to be sterilized are exposed to these conditions for at least 20 minutes. To be distinguished from steam sterilizers are the hot air sterilizers, which are easier to operate. They operate with dry heat at temperatures up to 250 degrees Celsius. The sterilization time in these devices is at least 30 minutes. Radiation sterilizers are also used today and work with UV rays, electron bombardment or beta and gamma rays.
Structure and mode of operation
Steam sterilizers are constructed similar to Papin’s pot. This tightly sealed vessel paved the way for the modern pressure cooker in the 17th century. In the hermetically sealed autoclaves, air is completely replaced by steam and organic cells are destroyed at high pressure. Usually, this condition is achieved via alternating periods between pumping down and flowing in. That is, air is pumped out piece by piece and steam is let in piece by piece. Inside the equipment, a heat of at least 120 degrees Celsius is released at an overpressure of several bar, and an absolutely water vapor-saturated atmosphere is present. The period of time required to create a vacuum is also known as the heating time. This process is followed by the equilibration period, which is used to establish the required temperatures inside the item to be sterilized. This period is followed by an exposure time, during which the killing of germs takes place. During the cooling time, the sterilized goods cool down and are aired out. Steam sterilization therefore works by heating in a moist state. In hot-air sterilizers, on the other hand, sterilization takes place via moving and dry hot air that flows around the item to be sterilized and thus flames it. Hot-air sterilization operates at such high temperatures that it is absolutely unsuitable for paper and textiles. In radiation sterilization, in turn, ionizing rays destroy the nucleic acids of microbial cells. All sterilizers rely on a gas-tight sealed mold.
Medical and health benefits
Since I. Semmelweis, the medical community guessed that strict hygiene measures were likely to reduce deaths during surgical procedures and other medical treatments. Until then, physicians had considered hygiene to be of lesser relevance and had, for example, operated in black coats that did not need to be washed after each operation. Cleaning of instruments and the surgical field was also not very common at the time. A breakthrough in this respect was achieved by J. Lister. He used carbolic as a cleaning agent for hands, medical instruments and the surgical field. In this way, he succeeded in creating a low-germ atmosphere and thus reducing the risk of infection. As soon as the microscope was used, medicine acknowledged the existence of pathogenic germs. Asepsis became established as a requirement for medical procedures and instruments. Mere cleaning of instruments became disinfection and finally sterilization. Inventions such as sterile rubber surgical gloves were born. Sterilization differs from disinfection in its requirement. The goal of sterilization is to achieve 100 percent sterility. Although this complete sterility can still not be guaranteed in practices or hospitals, the residual content of reproducible microorganisms after sterilization is a whole power of ten lower than after disinfection alone. The medical and health benefits of sterilizers are accordingly high. Medical sterilizers are a fundamental purchase for medical institutions in the Western world in this day and age, as a lack of sterility of surgical instruments and other instruments would be a negligent and irresponsible use of patient lives according to the findings of asepsis.
