A CSS unit is divided generally into distinct areas based on unique functions (4,5). These areas should be partitioned into separate units whenever possible; separation of soiled and clean work areas is especially important to minimize spread of contamination. The receiving, decontamination, and cleaning area has work tables, sinks, and equipment to facilitate sorting, initial decontamination of, and thorough cleaning of devices and reusable items. Some washer-decontamination equipment units are designed with passthrough doors to allow items to move from the soiled area to a clean area in a single pass, thereby avoiding recontamination (4). The clean side of a CSS unit encompasses several functions. These include a preparation and packaging/tray
assembly, the sterilization area where the various sterilizers are located, an area for ethylene oxide (ETO) sterilization and aeration (if such a sterilizer is present), and a storage space for sterilized packs. If the hospital has a laundry on site, the surgical pack room where clean textiles are prepared for surgical packs to be sterilized may be located on the clean side as well (6). Other function-specific areas within the CSS unit include (a) a materiel management area (if assigned to the CSS unit) for incoming new, packaged manufactured supplies; (b) an equipment and cart holding area for sterilized packages awaiting distribution within the hospital; (c) an equipment storage area; (d) housekeeping and a housekeeping equipment storage room; (e) the personnel support area; and (f) the administrative area.

The design of a CSS unit takes into account the flow of the work load and the type of material distribution system. Distribution may be accomplished by automation (e.g., vertical or horizontal conveyor, pneumatic tube systems), powered delivery carts, or manual pickup and delivery. Hand washing facilities should be conveniently located throughout all areas within the CSS unit (4,5). Emergency eye wash stations and showers should be available in areas where chemicals are used (5). The layout of the CSS unit should allow for adequate space for personnel and equipment/cart movement. Clean areas should have adequate space for work tables and appropriate equipment and sterilization supplies support to facilitate the assembly of instrument trays and packages for sterilization. Equipment and cart areas should be readily accessible from the clean areas. CSS units may or may not serve as materiel management operations for the facility. If this function is assigned to CSS, the decasing/breakout area is used to accommodate the unpacking and distribution of manufactured clean supplies to locations elsewhere in the hospital. Alternatively, some of the purchased items may be sent to the preparation/assembly area to be packaged for sterilization. The material management area is usually located near the clean area but not in it (4,5). This helps to prevent introduction of environmental contamination often associated with packaging materials such as corrugated cardboard. The personnel support area provides space for toilet, shower, and locker facilities for employees. If the surgical pack room functions are assigned to the CSS unit, this is usually a room where clean textiles are inspected, repaired as needed, folded, and assembled into wrapped packs to be sterilized (6). If the hospital’s laundry service, including surgical pack assembly, is provided by an outside contractor, the CSS unit must develop policies and procedures to have those packs delivered to the CSS unit for sterilization.

Adequate humidity, ventilation, and temperature control are important for prevention of environmental contamination of reprocessed items, provision of appropriate storage of sterile goods, and maintenance of a safe workplace. Temperatures in CSS areas vary, but it is common to find the temperature in general work areas, administrative areas, and personnel support areas set at 75°F (24°C). The main exception is for the cleaning/decontamination area where temperatures are in the range of 60°F to 68°F (15.6°C-20°C) as recommended by the Association for the Advancement of Medical Instrumentation (AAMI) (5). This provides an adequate comfort range for the workers who must wear substantial protective attire throughout the day. Humidity levels in CSS areas should be set generally in the range of 30% to 60% (4,5). The ventilation system should be designed so that air flows from clean areas into soiled areas and is exhausted to the outside or, if recirculated, passed through an appropriate bank of filters (e.g., a high-efficiency particulate air [HEPA] filter) for return to the system (4,5). Depending on which standards organization’s benchmarks are used for reference, 4 to 10 air changes per hour (ACH) are specified for CSS ventilation, with a minimum of 6 to 10 ACH in the cleaning/decontamination area and a minimum of 10 ACH in the area where the sterilizer equipment is located (4,5). The areas under negative pressure (i.e., cleaning/decontamination, sterilizer loading area, and restrooms/housekeeping) are vented directly to the outside, whereas air from the other areas of CSS can be recirculated. Table 70-1 depicts the ventilation benchmarks set by two major standards resources.

The Joint Commission has updated the hospital accreditation standards for 2011 to reflect adoption of the Facility Guidelines Institute (FGI) 2010 Guidelines for Design and Construction of Health Care Facilities (4,7,8). According to the Joint Commission, architects and design engineers for any new hospital construction or major renovation projects (including those in the CSS unit) initiated after January 1, 2011, need to use the 2010 edition of the FGI guidelines or look to relevant state rules and regulations pertaining to hospital construction.

The availability and configuration of systems that provide steam, hot and cold water (or water of a temperature specified by reprocessing equipment manufacturers), distilled or demineralized water, compressed air, nitrogen, vacuum sources, electrical power, air exhaust, and drainage of sewage are important to consider when designing the CSS unit and installing equipment (3,4,5). The electrical system in the unit should allow for the safe and efficient operation of equipment and provide for adequate lighting. Availability of a source of uninterrupted power is recommended in the event of an emergency (5).

Moist heat sterilization methods (i.e., saturated steam under pressure) remain the primary choice for terminal reprocessing of heat-stable instruments and devices. The quality of the steam is critical to the efficient operation of these sterilizers, and there should be sufficient steam capacity engineered into the system to accommodate this demand. Hospital boiler systems may not be capable of providing steam of sufficient quality; self-contained packaged steam generators are another option. If a boiler is used, the equipment must be serviced and maintained by trained personnel. Additionally, the steam distribution system and piping should be insulated to prevent steam condensation to water while en route to the sterilizer (9). Steam delivered to the steam sterilizers should be saturated steam with a steam quality between 97% and 100% (5,10). The purity of the steam should meet or exceed International Standards Organization (ISO) recommendations for limits on heavy metals, conductivity, pH, appearance, hardness, chlorine, phosphate, and evaporate residue (5,11).

The essential first step to any terminal reprocessing strategy for reusable medical instruments and devices is the reduction of bioburden. Debris such as blood, mucus, oil, or other foreign matter interferes with the sterilization process by acting as a barrier to the sterilizing agent (5,12,13). Additionally, cleaning and decontamination of used instruments render those instruments safe for CSS unit staff to handle during further reprocessing (14). Retained debris can also affect the functionality of a device at the point of use, resulting in additional patient safety concerns (15).

A process definition of cleaning is the removal of all adherent visible soil from the surfaces, crevices, joints, and lumens of instruments. Decontamination is the physical or chemical process that renders a potentially contaminated, inanimate object safe for further handling (5,15, 16, 17 and 18). The techniques for instrument cleaning and decontamination are manual scrubbing with brushes, ultrasonic cleaning, and processing with a washer-sterilizer or washer-decontaminator (15).

Initial Considerations Instruments in general should be kept moist prior to cleaning. Dried-on debris is more difficult to remove. Disinfection or sterilization cannot be accomplished if gross contamination is present on the instruments at the time when the final reprocessing steps are initiated (12,15,16,18,19). Instruments should be covered with a wet cloth and then contained for transport to the CSS unit. Soaking instruments in water or other fluid during transport is discouraged because of the risk of spills and the danger of injury to workers in lifting heavy basins or containers. Once in the CSS area, instruments contaminated with organic matter may be immersed in an enzyme detergent solution to enhance manual or mechanical cleaning effectiveness. Enzyme soaks keep debris suspended in solution, preventing its deposition and drying onto the surface of instruments. When employing this method, care should be taken to use the appropriate use-dilution, water temperature, and soak times as provided by the specific manufacturer of the enzyme detergent. Additionally, workers may get a false sense of security about the safety of handling the instruments immersed in a presoaking solution. These instruments are not yet safe to handle without personal protective equipment (PPE).

The use of an appropriate detergent avoids damage to instruments, prolongs their use life, and prevents the creation of crevices in which debris can collect (20,21). One inadvertent result of the implementation of Standard Precautions has been the increasing use of disinfectant/detergent agents for presoaking or manually cleaning medical instruments. Agents that contain chlorinated compounds (e.g., bleach) or that are highly acidic or alkaline can damage the surface layer of stainless steel instruments, resulting in corrosion and weakening. It is important to use only those detergent and disinfectant products specifically labeled for instrument cleaning. Hard surface disinfectant/detergents registered by the U.S. Environmental Protection Agency (EPA) are generally intended for cleaning and disinfecting large environmental surfaces (e.g., floors, walls, and table tops) and are not appropriate for general use on instruments.

Manual Cleaning Manual cleaning of instruments at the sink is still done and may be necessary for powered equipment and some extremely delicate items or to apply direct water pressure to contaminated lumens. Cleaning agents commonly used in manual cleaning contain surfactants, and some mechanical cleaning action (i.e., scrubbing, brushing) is needed for the effective removal of organic matter. During the cleaning and decontamination process, personnel must wear appropriate protective apparel (e.g., fluid-impervious gown or apron with full sleeves, latex or vinyl gloves that resist puncture or tearing during the process, face shield or surgical mask and goggles, a hair covering, and impervious shoe covers) (22). Such items provide the worker with protection from wetness and exposure to body fluids and tissues (23). Splatter or aerosols generated during hand scrubbing should be kept to a minimum through appropriate cleaning techniques (e.g., keeping brushes under water during scrubbing) (5).

Whenever possible, scrubbing the devices by hand should be avoided, because it increases the worker’s contact with contaminated surfaces and involves the added danger of handling sharp and pointed objects, thereby increasing the risk of sustaining percutaneous injuries. Sharp instruments should not be cleaned by hand when they can be effectively washed in a machine. Furthermore, contaminated, reusable sharps must not be stored or reprocessed such that the worker would have to reach into a container to retrieve the item (20). Alternatives that can help prevent these injuries include using forceps retrieval or a perforated tray so that the devices can be cleaned in situ (22).

Ultrasonic Cleaning Ultrasonic cleaning is a method that reduces the need for hand scrubbing. The ultrasonic washer cleans by cavitation, a process whereby sound waves produce vigorous microscopic implosions of tiny vapor bubbles on the surface of objects immersed in the cleaning chamber (5,13). This agitation causes a vacuumscrubbing action, pulling out fine debris particles from manually inaccessible surfaces (e.g., box-lock joints and serrations). Ultrasonic cleaning is not suitable for all devices. Refrain from using ultrasonic technology on chrome-plated instruments; powered instruments; endoscope lenses; or items made of rubber, silicone, or plastic (24). Items should be rinsed to remove gross soil before being placed in the ultrasonic washer. When grossly soiled items are placed into the ultrasonic washer, the process is less effective because the debris absorbs the sound waves. The water needs to be changed more frequently as well to minimize the amount of tissue and gross soil, but also to minimize the buildup of gram-negative bacteria, biofilm,
and endotoxin. Ultrasonic technology produces aerosols that reflect the fluid contents of the chamber; operation of the ultrasonic cleaner unit without a chamber cover allows these aerosols to escape. Because of this, the ultrasonic washer should be located in the decontamination area of the CSS unit. The potential hazards to personnel from aerosolization of such contaminated fluids should be considered when planning CSS worker safety programs. Exposure to such fluids should be prevented by use of engineering controls, changes in work practices, or use of PPE. The unit’s chamber should be disinfected, rinsed, and dried at the end of the day. The manufacturer’s directions should be followed for optimal results (5,17,18,20,24,25).

Automated Reprocessing Systems Washer-sterilizers use one of two methods to wash chamber contents. The first is a flooding technique, in which the chamber partially fills with water to which detergent has been added and then is agitated by blowing steam into the chamber through the water. These units generally operate at 270°F (132°C). This is an inefficient cleaning method that should not be relied on when there are lumened or complex devices in the load. The second method is generally used in larger, tunneltype units. In these, rotating spray arms create water jets that clean by impingement. In this second category, most machines reach a temperature of 285°F (141°C) (17).

Washer-decontaminator or washer-disinfector machines easily remove excessive amounts of debris from instruments by using spraying water aimed to cover all parts of the load. The numerous water jets allow excellent cleaning even if instruments are grossly soiled. The agitation of the water is such that it cleans instruments thoroughly without tossing them about, thereby reducing the risk of damage to delicate items. The operating water temperature is generally around 140°F (60°C), below the level at which protein rapidly coagulates, making removal easier than at higher temperatures (15,25). Appropriate soap and disinfectant should be used in accordance with the manufacturer’s instructions (17).

Automated cleaning/decontamination equipment must be loaded, operated, unloaded, and serviced in accordance with manufacturer instructions (22). Washer racks should never be overloaded, and the placement of loaded racks in the equipment chamber should allow sufficient clearance for the water jet arm to move freely. Instruments in the racks and trays should be open and disassembled if appropriate to allow maximum contact with water and cleaning agent. Routine service typically includes visual inspection for mineral deposits that should be removed.

It is important that these automated systems are cleaned and maintained regularly in accordance with the manufacturer’s instructions to prevent the colonization of the equipment with bacteria (e.g., Pseudomonas aeruginosa or nontuberculous mycobacteria [NTM]). Outbreaks of HAIs and episodes of pseudoinfections related to endoscopy and bronchoscopy have been attributed to contaminated washer-disinfectors through molecular epidemiology and strain identification techniques (26, 27, 28 and 29). Bacteria, particularly those microorganisms commonly found in tap water (e.g., Pseudomonas species), can become resident in poorly maintained equipment through the formation of biofilms that may help protect the bacteria from inactivation with liquid chemical germicides (29, 30, 31, 32, 33 and 34). This phenomenon has led some to explore ways to enhance quality assurance of the process in the interest of patient safety. A recent issue of debate is the sampling of the automated endoscope reprocessing system (AER) rinse water to help verify that in-line bacteriologic filters are performing according to specifications (33). This position, however, is still not widely embraced by the endoscopy community at present, although debate continues (13,35).

Automated cleaning/decontamination processing is not indicated for all instruments and devices. This processing is not appropriate for washing electrical devices, batteryoperated devices, or pneumatic operated equipment and devices (22). Instruments and devices with such features must be cleaned manually. However, the use of automated cleaning/decontaminating systems offers some advantages over manual cleaning. The process is controllable and minimizes worker contact with contaminated items (14,36). Automation can enhance the quality assurance for the cleaning portion of the overall instrument reprocessing strategy. A wide variety of mechanical washer-cleaners from a number of manufacturers is available, and new technology continues to be developed. New innovations that increase worker safety and protection are especially in demand (37). No single approach to decontamination and cleaning is effective for all instruments and degrees of contamination. Risks and benefits are associated with each method, and it is the responsibility of the CSS unit director to become familiar with relevant standards, guidelines, and information from the medical literature to determine best practices for decontamination and cleaning.

Endoscope Reprocessing The cleaning and terminal reprocessing of flexible fiberoptic and video endoscopes and bronchoscopes are often performed by specially trained technicians in the care units where these instruments are used. Nevertheless, CSS managers should have some oversight of the policies and procedures in these satellite reprocessing areas. Briefly, endoscopes (categorized as semi-critical devices according to the Spaulding Classification) are cleaned and subjected to either sterilization or high-level disinfection (13,38). From a practical perspective, high-level disinfection is chosen because these devices are heat sensitive (thereby precluding use of steam sterilization), but also for effectiveness of this disinfection process and its reasonably rapid turnaround time (39). At present, the only sterilization process available for endoscope reprocessing is that of ETO sterilization. However, this process may not be suitable or appropriate for makes and models of endoscopes, and the required aeration time is very long (e.g., ˜18 hours), which makes this an impractical choice (13,40, 41 and 42). Immersion in a liquid chemical sterilant is also an impractical method due to the lengthy contact time periods (e.g., 10 hours). The practical alternative (i.e., liquid chemical sterilization using peracetic acid as the active ingredient in a proprietary system [Steris System 1, S20 sterilant]) is not an option at present due to recent regulatory action by the U.S. Food and Drug Administration (FDA). FDA has determined that this equipment and its proprietary chemical agent are adulterated and misbranded products (43). Consequently, this chemical sterilizing system has been withdrawn from the market (44).

Effective reprocessing of these instruments begins the moment they are removed from the patient (13,38). All surfaces of the endoscope or bronchoscope should be kept moist until cleaning and further reprocessing can be performed. Although endoscopes can be cleaned with manual scrubbing and disinfected using immersion into liquid sterilant (with a short contact time validated for disinfection) or high-level disinfectant, AERs for washing and disinfection are the predominant choice for the reprocessing of these instruments primarily for the effectiveness of the process, but also because of space limitations in the care unit. One critical point to remember is that all AERs on the market today require that the endoscope or bronchoscope be manually rinsed so that gross soil is removed before placing the instrument in the AER. Some units also require the use of special connection devices that may be specific to a type or model of instrument (26). Use of appropriate connectors helps to ensure that the liquid chemical sterilant or high-level disinfectant can effectively reach the interior surfaces of the instrument’s channels (13,45) Thorough rinsing with sterile water, or tap water if sterile water is unavailable, is necessary to remove disinfectant residues that could lead to adverse patient reactions (13,38). An alcohol rinse is used primarily as a drying agent to help eliminate any residual moisture in the lumen of the device. Reprocessed endoscopes should be hung vertically in a designated cabinet to drain and dry until next use (13,38). A reprocessed endoscope should never be stored until next use in its original case (with the original protective padding). This practice prevents the internal channels of the instrument from drying in a timely manner, but more importantly the padding in the case usually becomes wet, leading to a buildup of bacterial contamination of the padding that in turn will contaminate the endoscope (13,38).

Materials used for hospital instrument wrapping and packaging should provide a cost-effective means of containment to maintain the sterility of the contents (5,22,46). An intact wrapper impervious to extraneous microbes, moisture, dust, and soil, and strong enough to resist punctures and tears during normal handling, theoretically should protect properly sterilized material indefinitely. However, such materials may also impede the passage of steam, ETO, or the sterilants in low-temperature sterilizing systems, thus interfering with the sterilization process. Therefore, compromises from this ideal must be made for items processed in healthcare facilities because of the limited choices available for terminal sterilization. Additionally, wrapping materials should (a) provide a seal of proven integrity, (b) be resistant to delamination when the pack is opened, (c) be free of pinholes, (d) allow suitable printing or labeling, (e) minimize the generation of nonviable particles, (f) provide evidence of tampering, and (g) produce minimal or no lint if fabric is used (47, 48 and 49).

Packaging materials should be compatible with the sterilization process. When the steam sterilization process is used, the materials should allow adequate air removal, steam penetration, and drying (5,46). When ETO sterilization is used, materials should allow adequate penetration and release of the gaseous sterilant and moisture, a function that is especially important during aeration. Packaging materials for use with hydrogen peroxide gas plasma sterilizers and ozone sterilizers should be made from materials that are compatible with those processes to allow effective sterilant penetration and will not interact with the contents of the pack (46). Manufacturers of sterilizer equipment should provide the user with some indication of which packaging materials are suitable for their units.

Packaging materials should also be inexpensive, impervious to bacteria, sealable before sterilization, and flexible enough to permit swift wrapping and unwrapping (46,50,51). Materials should be evaluated and selected according to their performance properties rather than according to whether they are woven, nonwoven, reusable, or disposable (52).

Muslin (i.e., 140 thread count, 100% cotton fabric) was the standard for many years in packaging for healthcare facilities, and some healthcare facilities continue to use textile packaging. Other fabrics have been used for packaging, including duck cloth, twills, barrier cloth, and treated barrier fabrics (22). Textile packaging is generally a reusable product, but this means that the textile needs to be laundered and inspected for fabric integrity. Patching of reusable fabrics is acceptable as long as the patches are applied with adhesive and not sewn in place. The critical factor is the amount of nonoccluded surface left after patching and folding (6). It is also important that textile packaging be stored at room temperature and humidity for at least 2 hours before use. This approach minimizes moisture buildup in the textile, thereby preventing superheating of the pack contents during steam sterilization (22).

Before a textile wrapper can be marketed, the product must be cleared by the FDA for use as a sterilization wrapper. In addition, consideration should be given to requiring that the material pass the American Society for Testing and Materials (ASTM) standard test method for resistance of protective clothing materials to synthetic blood (53).

Durable containment for instruments and devices is another option. FDA-cleared rigid containers, instrument cases, instrument cassettes, and organizer trays are commonly used (46). Regardless of what type of packaging is used to prepare packs for sterilization, packs should not exceed 25 lb in weight (46). This includes both the contents of the pack and the wrapper or containment.

Policies and procedures for in-house packaging should be written, reviewed annually, and readily available within the institution (46,47, 48, 49, 50, 51 and 52,53,54, 55, 56, 57 and 58).

General Principles The first thing that must be considered before subjecting a cleaned, reusable device or patient-care item to a sterilizing process is whether or not the materials are compatible with that process. Saturated steam sterilization is the most commonly available processing method in healthcare facilities, and it should be used whenever the device or instrument can tolerate moist heat because of the inherent reliability and robustness of the process and its low cost relative to other methods. However, heat-sensitive materials are being incorporated increasingly into modern medical devices and patient-care items. A number of modern, low-temperature sterilizing
systems provide alternatives for the sterilization of heatsensitive materials. When making the decision to purchase a low-temperature sterilizing system/equipment, it’s important to have a clear sense of what types of instruments and medical devices will be reprocessed in this equipment and to carefully consider the manufacturer’s equipment information and advisories for use. Some device materials may be incompatible with some of these newer processes, and such interactions may physically degrade the item, destroy its material, or leave toxic residuals on or in the treated item (58,59).

Currently, the FDA-cleared sterilization processes/technologies used in CSS units are: (a) saturated steam under pressure (steam sterilization); (b) ETO sterilization; (c) hydrogen peroxide gas plasma sterilization; (d) dry heat ovens; and (e) ozone sterilization. A detailed description of each of these processes can be found in Chapter 81 in this text.

It is important to remember, however, that all sterilizing systems have inherent limitations and that no single system can be used effectively for all instruments and devices (60). A common problem with any sterilizing system is the ability of the sterilizing agent (e.g., steam, gas, gas plasma) to diffuse throughout the chamber and the load so that the agent makes contact with all surfaces (both exterior and interior) of the items undergoing sterilization. In steam autoclaves, trapped air, either in the chamber or within an instrument or container, can prevent effective penetration of the steam to all surfaces in the load. Instrument design (e.g., a long, narrow lumen) can pose significant challenges both for effectiveness of the cleaning procedures and sterilant diffusion. Load configuration and density must be carefully controlled to allow air removal, sterilant penetration, and drying in steam sterilization cycles. This is especially critical if the sterilizer relies on gravity displacement to remove air (5,22). For steam sterilizers that have mechanisms to assist in air removal (e.g., dynamic-air removal using pulsing steam or vacuum conditioning phases), the configuration and density issues are not as great, but drying may still be a problem if the sterilizer is overloaded (5,22). The performance of low-temperature systems, including ETO and gas plasma, is particularly affected by the presence of residual organic matter, salt, and moisture (61).