Central Sterile Processing

Central Sterile Processing, also known as Central Sterile, Sterile Processing (Department), CS, and SPD, is a department found in hospitals. Other types of medical facilities that provide surgical services (for both animals and humans) generally provide some form of CS to their tenants. The main function of CS departments is the reprocessing of surgical instrumentation to allow further use on additional patients. This is in contrast to the use of single-use items, which are only used on one patient before being disposed of. Modern CS departments are fast paced, sometimes chaotic work environments. Technicians are required to know their job and have command over various skills and competencies, all of which impact the surgical outcome for any given patient.

Staff

Central Sterile departments are staffed by Central Sterile Technicians, or CS Techs. A small department might have only one or two techs, while the largest departments may have more than thirty. Technicians are classified into several different levels, depending on their skills and training: CS Tech I, II, III, and sometimes IV. Each level commands higher pay and more responsibility, with the most skilled technicians in a department classified at the highest levels. Overall control of the department generally falls under the director of the facility's Surgical Services department, while immediate control is given to the CS Manager or Supervisor, who may also have shift or team leaders to help with running the department's day to day operations.

Education & Training

Laws regarding education and training vary across the states, with New Jersey being the only state to require a license to work in CS, while other states require merely a high school diploma. To reach classifications above Tech I, however, a CS technician is required to register with the International Association of Healthcare Central Service and Materials Management (IAHCSSM) and pass a certification exam. The exam grants the certification of CRCST, or Certified Registered Central Sterile Technician, upon successful completion. Other exams are available to grant further certifications, such as Certified Instrument Specialist (CIS). In order to apply for and take the exam, applicants must complete a self-study program (also available through Purdue University) that teaches the fundamentals of working in Central Sterile. Once a certification is earned, a minimum of 12 continuing education (CE) hours must be completed each year (from April to April) to maintain the certificate. Failure to submit 12 CE points within the allotted time results in the forfeiture of any and all certifications. Points are accrued at a rate of one point/hour. Twelve points are required for techs certified as a CRCST only. Each additional certificate beyond CRCST requires an additional 6 points, up to a maximum of 36 points for a tech certified as a CRCST, CIS, CHL and CHMMC.

Function Within the Facility

CS is one of the most important departments within a hospital. It is absolutely vital to the function of the operating room(s), as it supplies sterile surgical instruments and other equipment, such as cameras, endoscopes, and patient positioning devices. CS also works with patient care units to provide clean and disinfected equipment, sterile instruments, and emergency equipment containing sterile supplies, such as crash carts. CS also manages sterilization for other departments in the hospital who might provide minor surgical services, such as Labor & Delivery, Cardiac Cath Lab, and Interventional Radiology. A particularly critical department served by CS is the ER. As ERs typically handle trauma patients who present to the hospital, it is important to have readily available, sterile instruments to provide these emergency services.

In addition to providing services to these "outside" departments, CS also sterilizes and manages inventory for the OR, and is critical to the outcome of each patient's surgical case. CS is responsible for verifying the completeness of each set, and the integrity, functionality, and cleanliness of each instrument in the set. Any failure on the part of Central Sterile to maintain these criterion can result in case delays, patient injury, non-optimal surgical outcomes, or total case cancellation, an expensive and frustrating outcome for both the surgical team and the patient.

Layout

Generally, Central Sterile Processing is divided into three areas: the clean side or Prep & Pack, the dirty side, or Decontamination (decontam), and Sterile Storage. Sets used during surgery return from the OR through decontam, where they are cleaned of any visible soil and processed through the washer-disinfector to make them safe to handle without gloves in Prep & Pack. Instruments and equpiment that cannot be sent through the washer-disinfector is disinfected manually, and passed through the pass-through window.

On the Prep & Pack side, instruments are unloaded from the washers and removed from the pass through window. At this point, instruments are loose inside their baskets, or un-assembled. Technicians on the clean side inspect sets for cleanliness and assemble their contents based on pre-made count sheets, which dictate what instruments in what quantity belong in each tray. After assembly, indicators are placed in each tray, and sets are packed for sterilization. After sterilization is complete, the sets move into Sterile Storage to be stored until use by the OR.

Equipment

Central Sterile is home to various types of machines and equipment used to re-process instruments and sets.

Decontamination Equipment

The main piece of equipment in Decontamination is the Washer-Disinfector, or simply washer. The washer uses high pressure streams of water with proteolytic enzymes and detergent to remove organic soil and residues from instrument surfaces. Lubricant is applied during washing to help maintain the functionality of the instruments. At the end of the cycle, load items are subjected to a disinfection phase, which exposes instruments and sets to water at or around 200°F for approximately 1 minute. This renders loads safe to handle without gloves in Prep & Pack. Another machine found in decontam is the ultrasonic washer, which uses ultrasonically induced cavitation to remove soil from delicate, complicated, and/or cannulated instruments. In larger hospitals that use the case cart system, Decontamination may also have a cart-wash, which is a large machine used to disinfect the OR's case carts. It functions much like a car wash, with a moving spray manifold that uses high pressure water and detergent to clean and disinfect carts.

Additionally, all Decontamination areas are equipped with large sinks, which are used during the removal of gross soil from instruments and equipment. Some areas also feature compressed air lines to help with drying manually washed instruments, and high pressure spray guns for the sinks, to help with removing organic matter or caked on blood.

Assembly & Packaging Equipment

Once sets have moved to the clean side, technicians have various items at their disposal to help assemble and package completed sets. The single most important item on the clean side is the count sheet. The count sheet is responsible for dictating what goes into a set and in what quantity. It is also used by the OR before and after a case to make sure all instruments are present in the room, and not left inside a patient. Surgical cases do not end until all instruments can be accounted for. Large CS units will usually have some sort of tracking system, which digitizes the count sheets for the technicians. They simply pull them up from the computer system based on the tray they're working on. Smaller hospitals will maintain their count sheets in paper form, as a small library where CS techs pull master sheets and copy them for use.

Other important items are those used for packing completed sets. Sets can be packed in either rigid containers or flexible, double thickness, spun-bound polyolefin wrap. Choice of container or wrap for basic sets varies from hospital to hospital, but some types of trays require wrap, so it is always found in CS units, while containers may not be. Individual instruments are packed in special pouches called peel-packs. Peel packs are plastic with steriliant permeable backing. The clear plastic side allows the contents of the pack to be seen, while the backing allows entrant of sterilant while forming a microbial barrier.

Sterilization Equipment

While count sheets are important for packing, the sterilizers are the most important machine in the department. Failure of one (or more) sterilizer(s) can seriously impact the surgical case flow, and in some cases result in total cancellation of some or all cases, as in the event of a natural disaster which cuts power to the hospital. The number of sterilizers in a CS department is determined by both the size of the department itself, and the caseload of the ORs. Small CS departments may only have one sterilizer, while large departments may have thirty or more.

Surgical caseload determines the types of sterilizers present in the department. ORs doing only a small number of general, basic surgeries need only a small steam sterilizer, while large hospitals working a diverse caseload will need large steam sterilizers and also low temperature gas sterilizers for delicate instrumentation.

Sterilizer Types

Steam

Steam sterilizers, or autoclaves, use high pressure, high temperature steam to rapidly inactivate all types of microbial organisms. A typical pre-vacuum steam cycle lasts 50 minutes for a small sterilizer, and up to 90 minutes for a large unit mounted in the wall. Standard cycle parameters are 4 minutes at 270°F (132°C) at 20-30 psi, followed by a 20 minute drying phase at a vacuum pressure of 20-30 inHg. Instruments steamed in an autoclave usually require a cooling time of 30 minutes to an hour after being unloaded from the autoclave, and before storage or use.

Gas-Plasma

The typical Gas-Plasma unit is the Sterrad system manufactured by ASP, a subsidiary of Johnson & Johnson. The Sterrad process is used to run instruments which would otherwise be destroyed by the steam process. The Sterrad uses hydrogen peroxide as the sterilant, delivered at a volume of 1750 μL with a concentration of 58%. At this concentration, the peroxide is damaging to human skin, so it is contained in cassettes; each cassette is loaded with 5 cycles. The sterilant is delivered to the chamber in vapor form and diffused through the load. Radio frequency energy is applied, creating a low temperature (90-100°F. Plasmas are usually found at temperatures similar to the surface of the sun) gas plasma composed of free radicals and ions, which inactivate micro organisms present in the chamber. At the end of the plasma phase, energy is removed and the individual hydrogen and oxygen atoms recombine into water and oxygen. This renders the load safe to handle and requires no special protective gear. Some models of the Sterrad can generate highly concentrated (99%) H2O2 in order to sterilize the tiny operating channels of certain types of flexible endoscopes.

Other types of gas plasma devices use ozone as the sterilant. Ozone usage provides the same level of sterilization as H2O2, with the added benefit of not having to maintain an inventory of pre-packaged sterilant. Ozone machines can make sterilant from plain atmospheric air, and after the plasma phase, atmospheric air is all that remains of the previously anti-microbial oxygen radicals.

Gas

Gas sterilizers use a gaseous sterilant to process instrumentation, and do not include a plasma phase as the Sterrad or ozone sterilizers do. Two common gas systems are the V-Pro, which is hydrogen peroxide based, and various ethylene oxide sterilizers.

The V-Pro is manufactured by Steris, and is similar to the Sterrad. The V-Pro, however, doesn't include a plasma phase during it's cycle, and has the ability to actively vaporize and remove any residual moisture that would affect load processing, while the Sterrad does not. It uses the same highly concentrated peroxide, but enclosed in cups containing 15 cycles instead of cassettes containing 5. Otherwise, it is basically the same as the Sterrad.

Ethylene oxide sterilizers use ethylene oxide (EO), a toxic chemical, to achieve sterility. It has fallen out of favor due to long cycle times, specific and delicate cycle parameters, the toxicity of EO to operators and patients, and long aeration times required to remove residues which can harm patients. Facilities using EO machines are required to monitor exposure to EO vapors, much in the same way that operators at nuclear power plants monitor radiation exposure.

High Level Disinfection Equipment

Central Sterile is also responsible for processing certain types of devices which do not have to be, or cannot be made, sterile. These devices are instead subject to high level disinfection, or HLD. HLD processes do not remove the maximum number of microbes from a given device, but instead reduce the microbial population so that subsequent infection is reasonably unlikely. Devices that can be processed by HLD are those that do not enter a normally sterile part of the human body, such as the trachea, or gastrointestinal tract.

HLD methods

Common methods for HLD are usually liquid based. Common methods in use are the Steris 1E system and Cidex OPA liquid high level disinfectant.

Steris 1E

The Steris 1E is a liquid system developed by Steris for processing of devices that are sensitive to steam and cannot be processed in gas or gas-plasma units, such as flexible gastroscopes and colonoscopes. It is truly a sterilization system, that results in sterile items after processing if they are used immediately. Devices that are not used immediately must be processed through the 1E again before they can be considered sterile. Because of this, the 1E is treated as a HLD system. It uses highly concentrated peracetic acid as the anti-microbial agent. This chemical is very dangerous, and must be handled with care. Devices to be processed are attached to the machine through a set of device specific "quick connects", which attach to various points on each individual device. The quick connects are attached to tubing which forces peracetic acid into the various device lumens and channels.

Because the 1E requires that devices to be processed are completely submerged in acid solution, devices must be leak tested before processing to prevent damage, and processed with water tight seals, if applicable. Any breach in the outer covering or surface of a Steris IE compatible device will render it unfit for processing, and processing at that point would likely result in the complete destruction of that device.

Cidex OPA

Cidex OPA is a liquid HLD agent consisting of 0.55% ortho-phthalaldehyde. This chemical is highly effective against a wide range of pathogens and microbes, and is non-toxic and not carcinogenic. It is, however, irritating to the digestive tract if swallowed and the lungs if inhaled. Cidex is dispensed into trays and basins of various shapes, and devices to be processed are submerged in the room temperature liquid for a minimum of 12 minutes to achieve HLD. Like the Steris 1E, devices must be leak tested prior to immersion, and some devices require conductivity tests as well.

Sterility/HLD Monitoring

All sterilization or disinfection processes occurring in Central Sterile are subject to various forms of process monitoring. A processed load of instruments or devices is not to be released for use until sterility or HLD can be reasonably confirmed beyond doubt. There are several products in the CS department to achieve this goal.

Chemical Monitors

Chemical monitors are used to confirm the success of a given process or cycle by way of a color change. They are divided into various classes as defined by the Association for the Advancement of Medical Instrumentation (AAMI). Class 1 indicators are used on seals for wrapped trays and locks for rigid containers, and only indicate that a given package came into contact with a sterilant, be it steam, peroxide, or acid. Class 1 indicators are not enough to indicate sterility or HLD on their own. They merely serve to differentiate processed packs and devices from unprocessed ones. Because of this, a class 3 single variable indicator, class 4 multi-variable indicator, class 5 integrator or class 6 emulator is included within each pack or device processed. Class 3 indicators respond only to one critical parameter of the sterilizer cycle, while class 4, 5, and 6 respond to multiple parameters of the cycle. Classes 3-6 are used inside trays and packs to verify sterility at the point of use.

Chemical monitors are also used to monitor entire loads. These load monitors consist of a challenge pack made of thick, heavyweight cards surrounding a class 5 or class 6 indicator. They are placed in an area of the sterilizer that is most difficult to achieve sterility in, and processed along with loads not containing implants. Upon completion of the cycle, they are examined, and if conditions were met and the color change is correct, non implant loads are then released to storage or to the OR for use.

Common chemical monitors for individual packs, devices, and loads include 3M's Comply integrator, Steris's Sixcess emulator for packs and Sixcess integrator challenge packs for loads, and Gettinge's Chemipack integrator challenge packs for loads.

Biological Indicators

Biological Indicators, or BIs, are vials containing live bacterial spores, commonly G. Stearothermophilius. Because bacterial spores are extremely difficult to kill, they make an excellent indicator of sterility when they are destroyed. BIs are used to monitor loads containing implants, and also to "certify" a sterilizer for daily usage. BI challenge packs are composed of a plastic BI vial and integrator made of and packed in heavy, thick paper. After processing, the challenge pack is opened and the BI is activated by crushing an ampule in the vial containing colored bacterial growth medium. Any color change or turbidity of the growth medium indicates the presence of microbial growth, and thus the failure of the processing cycle. The integrator allows CS to release loads containing implants to the OR for use, even before testing of the biological indicator is complete, but implants are tracked and monitored until the BI is verified to be negative for all bacterial life. The integrator card in the BI pack, like the chemical pack, is kept as part of the permanent legal record of device or instrument processing.

Common BIs include 3M's Attest BIs for steam sterilizers, Steris's Verify BI line for various sterilization processes, and ASP's CycleSure 24 for Sterrad systems.

Additional Monitoring Tools

In addition to the chemical and biological monitoring methods, pre-vacuum steam sterilizers are also subject to an additional test, known as a Bowie-Dick Test. Because pre-vac sterilizers require a vacuum to be drawn during the first and last phases of the sterilization cycle, it is imperitive to make sure that this is occuring. The Bowie-Dick Test originated as a method to verify air removal from the autoclave chamber. It is run as the first cycle of a pre-vac steam sterilizer every day, before any other instruments, sets, or devices are processed. Failure of the test indicates that the autoclave is no longer performing as specified, and must be taken out of service until it can be repaired. The test originally consisted of

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