Sterile processing departments (SPDs) have come a long way over the years, causing great leaps in patient safety, cost-effectiveness, and timeliness. While these strides have benefitted your SPD personnel and institution, sterile processing procedures have also become more technical, requiring more skill and training to make full use of their capabilities.

To make sure we are on the same page, it helps to outline what sterile processing is.

What exactly is sterile processing?

Reusable medical instruments have to be cleaned, inspected, reassembled, and sterilized after each use. The goal is to make sure the next patient who comes in contact with them is protected from dangerous bacteria and other pathogens. That equipment may come from general hospital areas, such as the Emergency Room or the operating rooms. Medical devices may be packaged as trays that contain all the instruments typically used in a specific procedure, in small kits, or separately.

For quality control, all hospital processing of reusable medical devices is typically done in a specialized area called the Sterile Processing Department (SPD) or the Central Sterile Services Department (CSSD).

The exact processes an instrument, or tray of instruments, goes through in the SPD is determined by its use, current hospital standards, materials of construction, and other factors. There are several steps to the sterile processing procedure, including:

    • Cleaning
    • Decontamination
    • Inspection
    • Preparation for sterilization
    • The actual sterilization process

Sterilization may take many forms, depending on the hospital requirements for specific instruments and materials:

    • Steam sterilization
    • Ethylene oxide
    • Vaporized hydrogen peroxide
    • Liquid chemical sterilization
    • Ozone sterilization

After sterilization is complete, the instrument or group of instruments can be sent back to stock O.R.s and procedure rooms or put into sterile storage until needed. Sterile processing personnel is specialized and trained to handle the procedures and recordkeeping needed to satisfy hospital policies and procedures and accreditation inspection standards.

How has sterile processing changed over the years?

Throughout history, different cultures knew that some form of sterilization was needed to prevent disease. As far back as 3000 BC, the Egyptians used pitch and tar to disinfect objects. Later on, doctors found that the fumes from burning sulfur could prevent infection from contaminated objects.

In 1680 Denis Papin, a French physicist, invented the first pressure cooker that would trap boiling water, convert it into steam, and clean objects by cooking them. Over the next two centuries, steaming was applied to sterilize linens, dressings, and gowns. A couple of major breakthroughs in the 1860s occurred when Louis Pasteur’s teachings caught on about how germs cause disease and cleansing prevented it.

Around the same time, the English physician, Joseph Lister, developed a technique that used carbolic acid as a spray to disinfect instruments. Instruments were still being soaked in carbolic acid to disinfect them in the early 1900s.

During the late 1800s, steam sterilization advanced, especially when surgical instruments were starting to be made out of materials that were better able to withstand high levels of heat. Their smoother surfaces also allowed for more thorough cleaning.

Besides the continued use of carbolic acid and steam, the 1900s saw more improvements in sterilization, introducing irradiation. More recently, sterilization of instruments incorporated ultraviolet light, and as a chemical that can be used on almost all instruments (metal and non-metal): ethylene oxide.

Also, in the 1900s, responding to the needs of military hospitals and aid stations, the German company Aesculap created the first rigid instrument container. This was originally made of stainless steel for safe transport of surgical instruments. And, while Germany continued to make strides in steam and chemical sterilization, it wasn’t until the 1930s when American manufacturers developed the first temperature-controlled sterilizer.

In 1956, Principles and Methods of Sterilization in Health Care Sciences by J.J. Perkins was published. This textbook set the standard and methodology for processing and sterilization of reusable medical devices. In 1963 glutaraldehyde was introduced, the first chemical solution approved by the Environmental Protection Agency (EPA) to sterilize heat-sensitive instruments.

Finally, in 1994, an American physician, William Rutala, working with the CDC published the Characteristics of an Ideal Sterilization Method:

  • The agent should be virucidal, bactericidal, tuberculocidal, fungicidal and sporicidal.
  • It should have the ability to achieve sterilization quickly.
  • It should be able to penetrate common medical device packaging materials and penetrate into the interior of device lumens.
  • There should be negligible changes in either the appearance or function of processed items and packaging materials, even after repeated cycling.
  • It should present no health risk to the operator or to the patient and pose no hazard to the environment.
  • It should have reasonable organic material resistance without loss of efficacy.
  • It should be suitable for large or small (point of use) installations.
  • Monitoring with physical, chemical, and biological process monitors should be able to be applied easily and accurately.
  • The cost should be reasonable for installation and for routine operation.

How important is the decontamination process in the sterilization process?

Decontamination uses physical or chemical processes to make sure that any equipment or reusable supplies are safe to be handled going forward. Here’s where fully utilizing CensiTrac’s decontamination software can make sure steps are not missed and efficiency goes up.

This process has several important steps:

Transport: All used supplies and equipment must be collected and safely transported to the SD. Hospitals are required to follow OSHA standards when transporting contaminated devices to protect people enroute, the device itself, and identify the device as biohazard.

Prioritizing transport and processing: CensiTrac’s OR scheduler interface provides the decontamination team in the SPD with visibility to the upcoming case schedule and surgical asset needs. With this information, technicians are able to identify the highest priority trays and reprocess those first. Tracking provides quick access to case cart contents and any special cleaning instructions as assets are received.

Protecting personnel working in the decontamination area: Protective clothing should include:

  • Water-repellent scrubs
  • Covers for shoes and all exposed skin
  • To prevent splashing, the face and eyes should be protected with a mask and goggles.

Sorting: This process can happen at different points, beginning at the point of use. Full PPE is required when sorting and preparing instruments for transport to the decontamination area. Discarding disposable sharps and other single-use items is typically performed at the point of use prior to transport. Instruments are treated to prevent bioburden from drying on the instruments.

Soaking – Instruments are soaked and washed per the manufacturer’s instructions for use (IFU). This can include soaking, brushing, and flushing lumens as outlined by the manufacturer’s IFU.

Washing: Both the type of washer and detergents should be determined by the materials in the device and the type of soil. Consult the device manufacturer’s instructions for use (IFU).

Washing equipment used may vary by institution and type of instrumentation. The most common ones in use include:

  • Washer/decontaminator: This type is used to clean heat-tolerant items. It cycles the load through multiple washes and rinses, followed by thermal disinfection to render instruments safe to handle.
  • Ultrasonic washer: High-frequency sound waves create vibrations to shake the soil from the surface of instruments. The vibrations cause the formation of tiny bubbles which then implode, creating minute vacuum areas that draw out the tiniest particles of debris from the crevices of the instruments. This process is called cavitation.
  • Tunnel washers: These washers are multifunctional because an ultrasonic is built into the process allowing for all instruments to go through a prewash, wash, ultrasonic, rinse, and dry process. Instruments being placed in a tunnel washer must be able to be submerged and withstand ultrasonic.
  • Cart washers: Any carts used to transport dirty instruments must also be routinely cleaned between uses. These washers are large enough to allow the carts to be wheeled into them and tipped to make sure all surfaces can be impacted. Following complete drying, carts can again be put into service.

Inspection: Once preliminary cleaning is accomplished, instruments can be safely inspected before packaging. During the inspection, some of the things checked include:

  • Cleanliness of box locks, serrations, and crevices
  • Sharpness of cutting edges of scissors, rongeurs, chisels, curettes, etc.
  • Chips, dents, stiffness, and alignment of jaws and teeth
  • Missing or damaged pins and screws
  • Disruption in the surface of plated instruments which can harbor bacteria, rust or create sharp edges

After inspection, any problems noticed can be addressed by re-cleaning or sending out for repair. CensiTrac can alert SPD personnel to routine maintenance required on instruments that might pass inspection. Individual instruments may have a certain number of reuses before maintenance is required. Having that information allows for quickly pulling those instruments due for maintenance, and substituting others for unbroken OR readiness.

What happens after decontamination and inspection?

After the instruments have been cleaned and inspected, they are typically sent to the preparation and packaging area of the SPD to be assembled into sets or trays. There are detailed instructions for assembling each set or tray. The CensiTrac O.R. scheduler interface helps technicians prioritize assets for assembly based on real-time O.R. needs.

CensiTrac allows technicians easy access to instrument images and approved substitutes. They can receive alerts if trays are incorrect or incomplete.

What does the sterilization process entail?

Once the instrument has been cleaned, inspected, and packaged for sterilization, it may be sterilized through one of these main methods of instrument sterilization. Reliable sterilization depends on the contact of the sterilizing agent with all surfaces of the item to be sterilized. The selection of the agent to achieve sterility depends primarily upon the nature of the item to be sterilized.

  1. Steam: The main form of sterilization in SPDs, a steam sterilizer, or autoclave, is used to sterilize items that can stand up to the heat and moisture of the steam. Steam sterilizers can be set for different types of cycles, depending on different variables: how much the load weighs and desired exposure and drying times. For pre-vacuum cycles, Bowie Dick Tests are required daily before any pre-vacuum cycles are run to check the efficiency of the air removal and steam penetration in the chamber.

To kill any contaminant requires direct exposure to saturated steam at 250 F (120 C) for at least 15 minutes. Temperature and time are inversely proportional: the higher the temperature, the shorter the time needed to achieve sterilization. Once the correct temperature and time have been achieved for that specific load, thoroughly drying it ensures continued sterility.

At the end of the sterilization cycle, the SPD technician reviews the sterilizer printout to verify if all sterilization parameters have been met.

  1. Non-Steam Sterilization: For materials and situations where high temperature and moisture aren’t appropriate, other methods of lower temperature sterilization can be used:
  • Ethylene Oxide Sterilization: This gaseous method can take somewhat longer than steam, up to 4.5 hours. The different stages include preconditioning the material, introducing the gas, exposing the material to the gas for the required time, evacuating the gas, and flushing the chamber. In some cases, with materials that are difficult to remove the ethylene oxide, aeration cycles may take up to 36 hours.
  • Vaporized Hydrogen Peroxide (hydrogen peroxide gas) Sterilization: According to the CDC, materials, and devices that cannot tolerate high temperatures and humidity can be sterilized by hydrogen peroxide gas plasma. This method has been compatible with most (>95%) medical devices and materials tested, such as some plastics, electrical devices, and corrosion-susceptible metal alloys.

During this process, hydrogen peroxide vapor fills the chamber to sterilize all surfaces and then be evacuated and converted to harmless water and oxygen.

  • Liquid Chemical Sterilization: This method uses EPA-approved chemicals such as peracetic acid, glutaraldehyde, and formaldehyde to provide effective reprocessing of devices, such as complex endoscope equipment.
  • Ozone Sterilization: Cleared by the FDA in 2003, ozone can now be used as the sterilant for processing reusable medical devices. Ozone sterilizers create their own sterilant using oxygen, water, and electricity. After the cycle, the ozone is converted back to oxygen and water vapor. It sterilizes by oxidation, a process that destroys organic and inorganic matter. Cycle time may be up to an hour, depending on the size of the chamber or load.

With so many surgical materials and sterilization methods, having a good surgical asset tracking system is essential to make sure you are applying them correctly and meeting all applicable standards.

Tests to determine sterilization effectiveness

Sterility assurance comes in the form of biological and chemical indicators. These indicators are used to monitor the sterilization process and show if the load was exposed to the appropriate conditions to achieve sterility. There are a variety of monitoring methods that can be used, based on the type of sterilization or what you want to measure. These types of tests can be used:

Biological Indicators (BI): These assess the sterilization process directly by killing known highly resistant microorganisms. They are used for routine monitoring.

Frequency of use is determined by hospital standards, the manufacturer’s instructions for use, and the facility policies and procedures. These may be done less frequently, so the CDC recommends also using mechanical or chemical indicators with each load.

Mechanical indicators: These involve technicians monitoring computer printouts, double-checking the sterilizer gauges, and documenting that the sterilizer meets the manufacturer’s specifications for temperature, pressure, and exposure times have been met. Any of these parameters being off during sterilization can alert staff as to failure of a load.

  • Chemical Indicators (CI): External and internal indicators change color to verify that one or more conditions required for sterilization have been achieved. External chemical indicators (process indicators) verify correct exposure of the entire set to the sterilization process. Internal chemical indicators should be used in every package to make sure the sterilant reaches the instruments and should be read right after the cycle. If it hasn’t changed to the correct color, that package of instruments should not be used.

Some of the messages that can be set up in CensiTrac to aid technicians include:

  • Visual and audible alerts to notify technicians of mismatches between items placed in a load and the chosen sterilization method
  • Visual prompts for technicians to include biological indicators in loads
  • Alerts to remind technicians when it’s time for periodic sterilizer testing

What’s next?

The functioning and accuracy of sterile processing departments are only as good as the personnel and their competency to follow all the procedures involved. As a sterile processing department manager, your job is to make sure each of your employees has the training to be successful. Censis has online and virtual training to make sure each employee is up to the task.