CSLB General Building (B) — All Questions

What is the fundamental difference between a gravity displacement cycle and a dynamic-air-removal (prevacuum) cycle?

• a.Gravity relies on incoming steam to push air down and out the drain, while dynamic-air-removal uses vacuum pulses to actively pull air out before steam is admitted✓
• b.Gravity operates at a lower temperature than any dynamic-air-removal cycle
• c.Gravity uses saturated steam and dynamic-air-removal uses dry heat
• d.Gravity requires a biological indicator while dynamic-air-removal does not

In a gravity cycle, steam entering the chamber displaces cooler, heavier air downward through the drain, which is slower and less reliable for porous items and lumens. Dynamic-air-removal cycles mechanically evacuate air with vacuum pulses or steam flushes so steam contacts every surface almost immediately. Both cycles use saturated steam, both are monitored with biological indicators, and both can run at 270 degrees F.AAMI ST79

A wrapped instrument set is being sterilized in a dynamic-air-removal steam sterilizer at 270 degrees F (132 degrees C). What is the typical minimum exposure time?

• a.1 minute
• b.4 minutes✓
• c.15 minutes
• d.30 minutes

Four minutes at 270 degrees F is the commonly validated exposure time for wrapped goods in a dynamic-air-removal cycle because air is removed before the exposure phase begins. Fifteen minutes at 270 degrees F and thirty minutes at 250 degrees F are gravity cycle parameters, which take longer because air removal is passive. One minute is not a validated exposure time for any wrapped steam cycle, and the device manufacturer instructions always govern the final selection.AAMI ST79

What is a standard gravity displacement steam cycle for a wrapped instrument set at 250 degrees F (121 degrees C)?

• a.3 minutes
• b.10 minutes
• c.30 minutes✓
• d.60 minutes

At the lower temperature of 250 degrees F, a gravity cycle needs about 30 minutes of exposure to achieve the required lethality, plus drying time. Shorter exposures of 3 or 10 minutes do not deliver sufficient lethality at that temperature for a wrapped set. Sixty minutes exceeds the validated requirement and unnecessarily stresses instruments; time and temperature are inversely related, so higher temperature permits shorter exposure.AAMI ST79

A technician opens the department at the start of the day shift and must schedule the Bowie-Dick test for a dynamic-air-removal sterilizer. How often is the test required?

• a.Once per week, on the same day each week
• b.In every load that contains an implant
• c.Only after a repair to the vacuum pump
• d.Each day the sterilizer is used, in the first cycle of the day after the warm-up cycle✓

The Bowie-Dick test verifies air removal and steam penetration and is run daily in an otherwise empty chamber before the first processed load, typically after a warm-up cycle. It is an air-removal test, not a lethality test, so it does not belong in implant loads and does not replace biological monitoring. It is also repeated after repairs, but that is in addition to, not instead of, the daily requirement.AAMI ST79

A Bowie-Dick test sheet comes out of the sterilizer with a pale, uneven center and darker edges. What does this indicate and what should be done?

• a.Incomplete air removal; the sterilizer should not be used for patient loads until the problem is corrected and a passing test is obtained✓
• b.A normal result caused by the density of the test pack; the sterilizer may be used
• c.Excessive steam pressure; reduce the set point and continue processing
• d.A failed biological indicator; quarantine all implants processed that week

Uneven or lighter color change, especially in the center, means residual air remained in the pack and steam did not penetrate uniformly, which points to an air leak, a faulty vacuum pump, or a plugged drain. The sterilizer must be taken out of service for patient loads until the cause is found and a passing test is achieved. A non-uniform result is never normal, and the Bowie-Dick test measures air removal rather than pressure or microbial kill.AAMI ST79

After a tray fails its internal chemical indicator, the supervisor reviews the fundamentals with the team. Which four parameters must all be satisfied for steam sterilization to be effective?

• a.Pressure, humidity, load weight, and cycle number
• b.Time, temperature, moisture in the form of saturated steam, and direct contact with all surfaces✓
• c.Vacuum depth, drying time, cooling time, and package integrity
• d.Detergent, water quality, temperature, and packaging material

Steam sterilization depends on saturated steam reaching every surface at the required temperature for the required time, which is why cleaning, correct packaging, and proper loading matter so much. Pressure is only the means of achieving the temperature, not an independent parameter. Drying, cooling, and cleaning variables affect the outcome and package integrity but are not the four critical parameters of the sterilization process itself.AAMI ST79

Why is saturated steam, rather than superheated or wet steam, required for steam sterilization?

• a.Superheated steam is too cold to kill spores
• b.Wet steam carries more heat energy and therefore sterilizes faster
• c.Saturated steam gives up its latent heat on contact with cooler surfaces, and both superheat and excess moisture disrupt that heat transfer✓
• d.Only saturated steam can pass through a sterilization wrapper

Sterilization depends on condensation, which releases latent heat directly onto the item surface, and saturated steam near 97 percent dryness delivers that transfer efficiently. Superheated steam behaves like hot dry air and requires far longer exposure times, while wet steam carries excess water that causes wet packs and reduced penetration. Steam of any quality can physically pass through a wrapper, so that is not the distinguishing factor.AAMI ST79

Peel pouches are being loaded onto a sterilizer shelf. What is the correct placement?

• a.Stacked flat, paper side up, no more than ten deep
• b.Stacked flat, plastic side up, so condensate runs off the film
• c.Laid flat and overlapping to maximize the number of pouches per shelf
• d.Positioned on edge in a rack, paper surface facing the plastic surface of the next pouch✓

Placing pouches on edge with paper facing plastic lets steam enter through the porous paper and lets condensate drain away, which also improves drying. Stacking pouches flat traps air and moisture between them and blocks the porous side. Overlapping pouches likewise prevents steam contact and is a common cause of wet packs and failed indicators.AAMI ST79

A mixed load contains wrapped metal basin sets and textile packs. How should the load be arranged?

• a.Place metal and basin items on the lower shelves and textile packs on the upper shelves✓
• b.Place textile packs on the bottom so metal weight does not crush them
• c.Alternate metal and textile items on every shelf for even heat distribution
• d.Place all items on a single shelf so the load remains compact

Condensate forms on and drips from metal items, so putting them low keeps that moisture off absorbent textile packs and prevents wet packs. Placing textiles beneath metal is the classic cause of soaked wrappers. Alternating or compacting the load restricts steam circulation and creates cold spots, and items should never be packed tightly against each other or the chamber walls.AAMI ST79

A tray is removed from the sterilizer and the outer wrapper feels damp to the touch. What is the correct action?

• a.Set the tray aside until the moisture evaporates, then send it to storage
• b.Consider the package contaminated, do not use or store it, and reprocess the contents after investigating the cause✓
• c.Wipe the wrapper dry with a clean lint-free towel and release the tray
• d.Place the tray back in the sterilizer for an additional drying cycle and then release it

Moisture provides a wicking pathway for microorganisms from the outer surface to the contents, so a wet pack is considered contaminated regardless of whether the cycle parameters were met. The contents must be rewrapped and reprocessed, and the cause must be investigated. Air drying, wiping, or re-running only the drying phase does not restore sterility to a package that has already wicked.AAMI ST79

Wet packs are appearing intermittently across several loads. Which of the following is the least likely cause?

• a.Overloading the chamber or packing items too densely
• b.Insufficient drying time or opening the door too early
• c.Using a dynamic-air-removal cycle instead of a gravity cycle✓
• d.Poor steam quality with excess moisture in the supply line

Dynamic-air-removal cycles generally dry better than gravity cycles because the post-cycle vacuum helps pull moisture out, so cycle type is not a likely cause of wet packs. Overloading, dense packing, short drying times, premature door opening, clogged drains, faulty steam traps, and wet incoming steam are all recognized contributors. Cooling loads on a cold metal surface or in a drafty area also produces condensation.AAMI ST79

After a steam cycle finishes and the load is removed, how should the load be handled?

• a.Transferred immediately to sterile storage to protect it from room air
• b.Placed on a solid countertop and covered with a clean towel while it cools
• c.Unloaded and immediately handled by staff wearing clean gloves
• d.Left undisturbed on the cart in a low-traffic, draft-free area until fully cool, typically 30 minutes or longer, before it is touched or moved✓

Hot packages are vulnerable because handling them can drive condensation and contamination through the packaging, so the load is left to cool on the cart away from vents, drafts, and traffic. Cooling times of 30 minutes to an hour or more are common depending on load density. Placing hot items on a cold solid surface or covering them traps condensate, and gloves do not protect a package that is still hot and damp.AAMI ST79

Immediate-use steam sterilization (IUSS) is requested for a single dropped instrument during a case. Which statement is correct?

• a.The item must still be thoroughly cleaned and decontaminated before it is placed in the sterilizer✓
• b.Cleaning may be abbreviated because the exposure temperature is higher
• c.The item may be flash sterilized unwrapped and stored for later use if kept covered
• d.IUSS eliminates the need for physical, chemical, and biological monitoring

IUSS shortens the packaging and drying steps, not the cleaning step, and a device that is not properly cleaned cannot be sterilized by any cycle. Items processed by IUSS are transported for immediate use and are not stored for later cases. Physical monitors and chemical indicators are used with every IUSS cycle, and the sterilizer is monitored biologically at least daily or weekly per policy.AAMI ST79

Which practice regarding IUSS and implants is correct?

• a.Implants may be routinely processed by IUSS as long as the case is urgent
• b.IUSS of implants should be avoided; if unavoidable in a documented emergency, a rapid-readout biological indicator with a Class 5 integrating indicator is run and the event is documented✓
• c.Implants may be processed by IUSS if a Class 1 process indicator is placed on the tray
• d.Implants processed by IUSS require no biological monitoring because the cycle is unwrapped

Because a failed implant sterilization carries severe patient consequences, implants should be sterilized in a full terminal cycle and quarantined until the biological indicator result is known. In a documented emergency, IUSS may be used with a process challenge device containing a rapid-readout biological indicator and a Class 5 integrating indicator, and the exception must be recorded. Convenience or urgency alone does not justify the practice, and an external process indicator only shows exposure.AAMI ST79

A typical IUSS gravity cycle for nonporous metal instruments only is 270 degrees F (132 degrees C) for 3 minutes. What changes when the item is porous, cannulated, or has a lumen?

• a.The temperature is lowered to 250 degrees F and the time stays at 3 minutes
• b.The cycle is unchanged because IUSS parameters are fixed
• c.A longer exposure, commonly 10 minutes in a gravity cycle, is required per the device manufacturer instructions✓
• d.The item cannot be sterilized by steam under any circumstance

Porous items, lumens, and complex devices are harder for steam to penetrate, so validated IUSS parameters extend the exposure time, commonly to 10 minutes in a gravity cycle. The device manufacturer written instructions for use always define the required cycle. Lowering the temperature reduces lethality, IUSS parameters are not fixed across device types, and most such devices are perfectly steam compatible.AAMI ST79

A surgeon sends a heat-sensitive device with a long narrow lumen and asks whether it can be processed with ethylene oxide. Which statement describes ethylene oxide sterilization?

• a.A high-temperature method used as the fastest option for routine metal instruments
• b.A liquid immersion method used at the point of use for endoscopes
• c.A dry heat method used for oils, powders, and petroleum-based products
• d.A low-temperature gas method used for heat-sensitive and moisture-sensitive devices, including many long or narrow lumens✓

Ethylene oxide sterilizes at low temperature and penetrates well, which makes it valuable for delicate electronics, plastics, and devices with long narrow lumens that other low-temperature methods cannot handle. Its drawbacks are a long total cycle including mandatory aeration and significant worker safety and environmental controls. Dry heat is the method used for oils and powders, and liquid chemical sterilants are the point-of-use immersion option.AAMI ST79

Why must every ethylene oxide load undergo an aeration phase before items are released?

• a.Residual ethylene oxide absorbed into plastics and rubber is toxic and must be driven off to protect patients and staff✓
• b.Aeration completes the microbial kill that the exposure phase started
• c.Aeration restores the humidity that was removed during the cycle
• d.Aeration is required only for loads that contain implants

Ethylene oxide is a recognized carcinogen and irritant that is absorbed by polymers, so mechanical aeration at elevated temperature is required to reduce residuals to safe levels before handling or patient contact. Aeration times of about 8 to 12 hours or more are typical and are set by the device and sterilizer manufacturers. The kill occurs during exposure, not aeration, and the requirement applies to every load regardless of contents.OSHA

A tray wrapped in a cellulose-based (paper) wrapper is about to be loaded into a hydrogen peroxide gas plasma sterilizer. What is the problem?

• a.Cellulose reacts with hydrogen peroxide to form a toxic residue on instruments
• b.Cellulose absorbs hydrogen peroxide and will cause the cycle to abort or fail, so only nonwoven polypropylene wrap and compatible trays may be used✓
• c.Cellulose wrap melts at the operating temperature of the sterilizer
• d.Cellulose wrap is acceptable if a second wrapper is applied over it

Hydrogen peroxide is readily absorbed by cellulose materials such as paper, linen, and cotton, which strips sterilant from the chamber and causes cycle cancellation, so only polypropylene wrap, compatible pouches, and approved containers are used. The issue is absorption, not toxic residue formation or melting, since the process runs at low temperature. Adding a second cellulose layer makes the absorption problem worse.AAMI ST79

What are the byproducts of a hydrogen peroxide gas plasma sterilization cycle, and what does this mean operationally?

• a.Ethylene glycol and chlorohydrin, which require a long aeration phase
• b.Formaldehyde and methanol, which require a chemical scrubber
• c.Water vapor and oxygen, so no aeration period is required and items can be used immediately after the cycle✓
• d.Ozone and nitrogen, which require ventilation of the room for one hour

Hydrogen peroxide breaks down into water and oxygen, so there is no toxic residual and loads are available for immediate use, which is a major advantage over ethylene oxide. Ethylene glycol and ethylene chlorohydrin are ethylene oxide byproducts that drive its aeration requirement. Formaldehyde and ozone are separate sterilization agents, not plasma byproducts.AAMI ST79

An ozone sterilization system is being introduced. Which statement about ozone sterilization is accurate?

• a.Ozone is generated from ethylene oxide and requires the same aeration as EO
• b.Ozone sterilizes at 270 degrees F and can replace steam for textile packs
• c.Ozone is used primarily for oils, powders, and anhydrous materials
• d.Ozone is generated on demand from oxygen and water, sterilizes at low temperature, and reverts to oxygen with no toxic residue✓

Ozone sterilizers create the sterilant on site from medical-grade oxygen and water, which removes the need for stored chemical cartridges, and the ozone converts back to oxygen at the end of the cycle. It is a low-temperature method for heat-sensitive and moisture-sensitive devices, not a steam substitute for textiles. Dry heat, not ozone, is the method for oils and powders, and ozone is unrelated to ethylene oxide.AAMI ST79

A department is deciding which sterilization method to use for a heat-stable stainless steel instrument set. Which method should be selected and why?

• a.Steam, because it is the safest, fastest, least expensive, and most reliable method for heat-tolerant and moisture-tolerant items✓
• b.Ethylene oxide, because it penetrates box locks better than steam
• c.Hydrogen peroxide gas plasma, because it is the shortest cycle available
• d.Dry heat, because it does not corrode stainless steel

Whenever a device tolerates heat and moisture, steam is the preferred method because it is nontoxic, inexpensive, well validated, and rapid. Low-temperature methods are reserved for devices that cannot survive steam, and each carries material restrictions, cost, and in the case of ethylene oxide, worker safety burdens. Dry heat requires very long exposure times and is limited to a narrow set of materials.AAMI ST79

A technician receives a jar of petroleum-based lubricant and a container of powder that must be sterilized. Which method applies, and what are representative parameters?

• a.Flexible endoscopes, at 250 degrees F for 30 minutes
• b.Oils, petroleum-based lubricants, and powders, at approximately 320 degrees F for 2 hours or 340 degrees F for 1 hour✓
• c.Rigid containers with filters, at 270 degrees F for 4 minutes
• d.Textile packs, at 275 degrees F for 3 minutes

Dry heat is used for anhydrous materials that steam cannot penetrate, such as oils, ointments, and powders, and it needs long exposure at high temperature because heat transfer without moisture is inefficient. Flexible endoscopes are heat sensitive and are high-level disinfected or low-temperature sterilized. The 270 and 275 degrees F short cycles listed are steam parameters, not dry heat.AAMI ST79

Rigid sterilization containers are being loaded into a steam sterilizer along with wrapped trays. What is correct practice?

• a.Stack containers three high to conserve shelf space
• b.Place containers on the top shelf so condensate drains onto the wrapped trays below
• c.Place containers flat on the shelf, do not stack unless the container manufacturer validates stacking, and keep them from touching chamber walls✓
• d.Turn containers on edge so water drains from the filter ports

Containers must sit level so condensate can drain through the designed pathway, and stacking is permitted only when the container manufacturer has validated it, because stacking can block steam access and trap moisture. Items should never contact chamber walls, where they can be scorched or collect condensate. Putting containers above absorbent wrapped packs invites wet packs, and turning them on edge defeats the drainage design.AAMI ST79

A technician notices the sterilizer printout shows the chamber reached only 268 degrees F during a cycle set for 270 degrees F, although the chemical indicator changed color. What should be done?

• a.Release the load, since the chemical indicator confirms sterility
• b.Release the load but note the discrepancy in the log for the next preventive maintenance visit
• c.Rerun the same load in the same sterilizer without further investigation
• d.Do not release the load; the physical monitor shows the cycle parameters were not met, so the load is quarantined and the sterilizer is evaluated✓

Physical monitors are an independent record of what the chamber actually did, and a load that did not meet its specified parameters cannot be released even if an indicator changed color. Chemical indicators respond to conditions but do not prove that all critical parameters were achieved. Rerunning without investigation ignores a possible equipment fault that will affect subsequent loads.AAMI ST79

Why must instruments with hinges, such as hemostats, be placed in the sterilizer in the open, unlocked position?

• a.Steam must contact every surface, and closed box locks and ratchets shield the mating surfaces from the sterilant✓
• b.Closed instruments trap air that lowers the chamber pressure
• c.Open instruments dry faster and reduce total cycle time
• d.Closed instruments will be damaged by the pressure changes in the chamber

Sterilization requires direct sterilant contact with all surfaces, and a closed ratchet creates a shielded metal-to-metal interface that steam cannot reach. Stringers, racks, and instrument pins are used to hold hinged instruments open throughout the cycle. Chamber pressure is controlled by the sterilizer, drying benefit is secondary, and correctly manufactured instruments are not damaged by normal cycle pressure changes.AAMI ST79

A student asks a technician what it means when a process is described as achieving a sterility assurance level of 10 to the minus 6. What is the correct explanation?

• a.Six log reductions of bioburden have occurred during the cycle
• b.The probability that a single item remains nonsterile after processing is one in one million✓
• c.Six biological indicators must be run in every load
• d.The sterilant concentration is one part per million at the end of the cycle

SAL is a probability statement about the likelihood that a viable microorganism survives on a processed item, and 10 to the minus 6 is the accepted level for devices intended for sterile use. It is not a count of log reductions achieved, although the two concepts are mathematically related through the starting bioburden. It has nothing to do with the number of indicators used or with residual sterilant concentration.AAMI ST79

A technician is loading a steam sterilizer and wants to fit as many trays as possible before the shift ends. How full should the chamber be loaded?

• a.Completely full, with items packed tightly so nothing shifts during the cycle
• b.At least three quarters full, because partial loads waste energy
• c.Loosely, with space between packages and between packages and the chamber walls so steam can circulate freely✓
• d.Only with identical items, never mixed loads, regardless of spacing

Free circulation of steam and unobstructed air removal require space around every package, so overloading is a leading cause of sterilization failure and wet packs. Packing tightly or filling to a minimum percentage for efficiency compromises the process. Mixed loads are acceptable when items are arranged correctly, for example metal below textiles, and when all items share the same validated cycle.AAMI ST79

A liquid chemical sterilant such as peracetic acid is used to process a device. What is the key limitation of this method?

• a.It cannot be used on immersible devices
• b.It requires an aeration period of at least four hours
• c.It produces a package that has a two-week shelf life
• d.The device is processed wet and unwrapped, so it cannot be packaged or stored and must be used immediately✓

Liquid chemical sterilization occurs in a chamber of circulating solution and the device emerges wet, meaning there is no barrier packaging and therefore no shelf life; the item is transferred aseptically and used right away. The method is intended specifically for immersible heat-sensitive devices. No aeration phase is involved, and the absence of packaging is precisely why storage is impossible.AAMI ST79

An instrument manufacturer's instructions for use specify a prevacuum cycle at 270 degrees F for 4 minutes with an 8-minute dry time, but department policy uses a 30-minute dry time for all trays. Which should be followed?

• a.Follow the longer validated department cycle only if it is also within what the device manufacturer permits; the device manufacturer instructions for use set the required minimum parameters and must be reconciled with sterilizer capability✓
• b.Always follow department policy, because it is approved by the infection prevention committee
• c.Always use the shortest parameters listed anywhere, to protect the instruments
• d.Choose whichever parameters the operating room requests for turnaround

Reprocessing must follow the device manufacturer written instructions for use, validated against what the facility sterilizer can actually deliver, and any conflict is resolved before the device is put into service rather than by local preference. Longer drying is generally acceptable, but exposure parameters cannot be shortened below the validated minimum. Turnaround pressure and blanket policy never override validated instructions.AAMI ST79

During a steam cycle the sterilizer aborts and displays an air leak alarm. What is the correct response?

• a.Restart the same cycle immediately, since aborted cycles do not affect the load
• b.Consider the load unsterile, remove it from service, and do not release it; report the alarm so the sterilizer can be evaluated and repaired✓
• c.Release the load if the external chemical indicators have changed color
• d.Open the door and allow the load to dry, then run a Bowie-Dick test and release the load

An aborted cycle means the process was not completed as validated, so the entire load is treated as unsterile and must be reprocessed after the equipment problem is resolved. An air leak specifically means air remained in the chamber and steam penetration cannot be assumed. External indicators show only that a package was exposed to some conditions, and a Bowie-Dick test performed later says nothing about a load that already failed.AAMI ST79