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Sterilization is strictly regulated in the medical field. In the USA, the Centers for Disease Control and Prevention (CDC) measure sterility according to SALs, or sterility assurance level, which refers to the probability of “a single viable microorganism occurring on a product after sterilization.” This is generally expressed with the number 10 to the power of n. For example, if the SAL is 10-6, the probability of a pathogen surviving the sterilization process is less than one in a million.

To protect patient safety, teams need to keep medical instruments sterile. This necessitates the use of sterilization solutions that prevent pathogens and contaminants from causing infection. Take a look at some of the equipment and best practices medical facilities are using to achieve this.

Chemical sterilization

Chemical sterilization is generally carried out at a low temperature, close to the ambient temperature of the medical facility itself. Sterilization occurs when chemicals come into contact with instruments used in medical treatment or the pharmaceutical production process, killing any germs or pathogens found on the instruments.

Ethylene oxide sterilization

Ethylene oxide is used to kill germs and pathogens that may exist on medical equipment. This is a low-temperature process, and so it is suitable for any instruments that cannot be exposed to high temperatures or states of vacuum. There are downsides, however, not to mention that this is a lengthy process of sterilization.

Because ethylene oxide sterilization is relatively slow, it may not be suitable for large-scale or busy medical facilities. On the other hand, facilities with low throughput requirements may find this to be a low-cost and effective option.

Vapor hydrogen peroxide sterilization

Vapor hydrogen peroxide sterilization has largely superseded ethylene oxide sterilization as the leading form of chemical sterilization for medical equipment. This is because the method is generally faster than using ethylene oxide, without compromising on results.

Different types of vapor hydrogen peroxide equipment are available, but the sterilization process is generally the same across all equipment pieces. It is always the vaporized hydrogen peroxide that actively achieves sterilization — the only difference between the equipment pieces relates to how the residual hydrogen peroxide is removed post-sterilization.

Autoclave sterilization

Autoclave sterilization does not use chemicals to remove pathogens and bacteria. Instead, it relies on water vapor — or steam — that has been heated to high temperatures. The temperature range may vary — and different types of instruments will require a different sterilization temperature — but most widely available medical autoclaves will be capable of between 250 and 275 degrees Fahrenheit.

Gravity displacement sterilization

During gravity displacement sterilization, steam is inducted into the topmost portion of the autoclave chamber. As this steam is more dense than the air in the chamber, it sinks through the autoclave — this is where the “gravity” component of the name comes from. The sinking steam pushes air out of the chamber via a vent at the bottom, which gives us the “displacement” component.

Gravity displacement has been used in sterilization for many years, but it is no longer the most efficient method available to medical practitioners. However, it does have a very specific use case. This sterilization method is very useful for sterilizing sensitive instruments that might be damaged by a vacuum.

  • Flash sterilization

Flash sterilization was developed as a way to improve the efficiency and usability of the gravity displacement method. Originally, this method involved exposing an unwrapped object to steam at 270 degrees Fahrenheit and 27 to 28 lbs of pressure for three minutes within a gravity displacement autoclave. Since development, however, the exact time and heat used have varied according to the type of instrument being sterilized.

This sterilization method is not necessarily recommended, especially after reports of a higher rate of infection following flash sterilization and even cases of patients who had been burned by flash sterilized instruments. While the method is permitted in the USA, great care should be taken to ensure that sterilization and cooling are carried out properly.

Dynamic air removal sterilization

The process of dynamic air removal sterilization utilizes a vacuum to remove air from the autoclave chamber. As a result, this method of autoclaving tends to be more efficient than the alternative — gravity displacement. Vacuum pressure is applied via pulses that alternate with pulses of steam. This method will be suitable for most types of medical instruments, although sensitive equipment may require the slower gravity displacement method.

The reason dynamic air removal sterilization is quicker is that air is removed from the chamber with greater efficiency. The sterilizing steam comes into contact with the instrument’s components more swiftly and with greater efficacy. In turn, the sterilization process is completed without delay, and teams can achieve reliable sterilization of a great number of instruments in a fraction of the time.

Other sterilization equipment and materials

The process of sterilization is a long one and, in fact, extends beyond the direct sterilization measures listed above. Medical instruments also need to undergo cleaning and preparation before the actual sterilization phase begins. This necessitates the usage of other equipment and materials.

Enzymatic fluid

This fluid is rich in enzymes designed to break up protein-based contaminants. These enzymes work via a process similar to human digestion, breaking up organic contaminants so that the instruments can be easily cleaned. Blood, bodily fluids, and other organic contaminants are removed in this way.

Instruments are soaked in this solution in large metal basins designed with this purpose in mind. In most cases, they will be placed in the solutions by hand.

Washing machines

Most pieces of medical or pharmaceutical equipment are then fed into a washing machine. These machines are similar to an industrial dishwasher found in a large-scale restaurant or hotel. The machine carries out more intensive washing after the instruments have already been soaked in the enzymatic fluid.

Sensitive instruments may need to be washed by hand or in a machine designed to handle these more fragile pieces of equipment. While some disinfection does occur at this stage, it is really just a phase of preparation ahead of the more rigorous sterilization procedure.

Sterile wraps

After sterilization, protective materials and wrappings are applied to keep the medical instruments sterile and ready for deployment. The CDC recommends that sterilized instruments be placed in a sterile storage area with a controlled temperature and humidity — up to 75 degrees Fahrenheit and 70% humidity.

Protect patient health and secure compliance

For medical facilities, protecting patient health should always be the priority. This is why sterilization solutions are critical to keeping medical instruments sterile and ready for use. The CDC and other regulatory bodies share this view, and their compliance requirements are designed to protect the health, safety, and interests of all patients right across the United States.