The sophistication of surgery has resulted in the need for more than the traditional steam sterilization. While most devices can be safely steam sterilized, many others are heat- or moisture-sensitive. So what are the alternatives and how realistic are they? Here's a look at the advantages and disadvantages of ethylene oxide gas (EtO), low-temperature gas plasma, peracetic acid, ozone and liquid chemicals (such as glutaraldehyde).

EtO ' effective and diverse
EtO is a chemical agent used to sterilize heat-, pressure- and moisture-sensitive items. A member of the ether family, also known as an epoxide, EtO is a liquid that, at room temperature, becomes a gas; it is used as a fumigant, pesticide and as a sterilization agent. Because it can be absorbed by many materials, it's a good choice for sterilization.

There are several types of EtO used for sterilization. The most common is the 100 percent formulation in undiluted unit-dose cartridges, which has become more predominant since the 1995 ban of chlorofluorocarbons (better known as CFCs), a result of their ozone-depleting action.

EtO mixtures include the addition of inert gases such as hydrochlorofluorocarbons (HCFCs) and carbon dioxide. However, a U.S. ban on HCFCs is scheduled to take effect after 2023.

Items must be clean and completely dry before sterilization, and all traces of lubricants (except those compatible with EtO) must be removed. Materials to be sterilized and their packaging should be maintained in an environment with a relative humidity of at least 50 percent. Most packaging materials that are acceptable for steam are also acceptable for EtO.

Because it is flammable in both the liquid and gaseous states, the Occupational Safety and Health Administration and the Environmental Protection Agency regulate EtO use and storage. OSHA regulations require that operators of the sterilizers must demonstrate competence in all of the parameters of EtO sterilization and a comprehensive knowledge of the system in use. In addition, you must monitor employee exposure to EtO, and special ventilation, alarm systems, spill plans and medical surveillance are required.

The usual cycle times range from one hour to 12 hours, depending on the temperature ' at 130'F, cycle time is usually 105 minutes. Due to the toxic nature of the EtO gas, all items processed must be aerated to remove the EtO before the device is considered safe for handling or use on a patient. This is where EtO sterilization gets slowed down, as aeration adds significantly to processing times.

A mechanical aeration cabinet can be used, although the aeration cycle is frequently built into the sterilizer. The cabinet or the sterilizer must have a dedicated exhaust system. The temperature at which you run the cycle determines the length of aeration time, typically

• 122'F for 12 hours,
• 130'F for 10 hours and
• 140'F for eight hours.

However, it's critical to check with the manufacturer of the device you're aerating for specific aeration recommendations. Never assume you know the answer to how long you should aerate an item.

The benefits of EtO outweigh the risks. However, one must be keenly aware of the health hazards associated with EtO residuals caused by improper or inadequate aeration, which can cause death or irreversible tissue damage.

EtO is classified by OSHA as a carcinogen and a reproductive hazard. Therefore, OSHA regulations govern employee exposure measures, sterilization installation and engineering controls, medical surveillance, leak detection and emergency situations, among other factors. As long as you take precautions, EtO is an acceptable and safe method of sterilization.

However, because of the costs associated with complying with OSHA regulations, EtO is more expensive per cycle than steam and most of the alternative sterilization methodologies. In addition, the extended time to properly and safely aerate devices (a complete cycle can take 12 hours to 16 hours) makes same-day turnover of devices unrealistic. You have to plan ahead for instruments that will be reprocessed by EtO.

Gas plasma ' no residue, less time
The first low-temperature gas plasma system was cleared by the FDA in 1993 as an alternative to ethylene oxide. Because it requires only an electrical hookup, installation is inexpensive. This sterilization method uses a small amount of liquid hydrogen peroxide, which is energized with radio frequency waves, turning it into gas plasma. The hydrogen peroxide is provided in multi-dose cassettes that contain 10 single doses of liquid (nominal) 59 percent hydrogen peroxide. Sterilization happens just below 122'F; there are restrictions on lumen diameter and length.

Sterilizer chamber size is approximately 3 cubic feet, and a double-capacity chamber size is now available. But you might not need the larger chamber, because with a quick 45 minute to 50 minute cycle time (depending on load configuration), you might be able to achieve the rapid turnover you desire.

Before putting any devices through LTGP sterilization, you must thoroughly clean and dry them. Any moisture remaining in devices can result in an abort of the cycle. Compressed air can be used to blow moisture out of lumens and other hidden places.

You have several options of packaging materials when putting instruments through LTGP sterilization. If you use instrument trays, look for ones that are designed to optimize diffusion of the hydrogen peroxide, and to minimize interference with the radio frequency energy and the absorption of hydrogen peroxide. Check with tray manufacturers before you purchase and use containers. Tyvek (all-plastic) pouches are compatible with LTGP; do not use linen, paper wraps, peel-packaging materials, paper-plastic pouches, polypropylene-based wraps or any cellulose-based material.

With your devices packed, they are ready for LTGP sterilization. Here's how it works.

• Vacuum. All air is removed from the chamber and packages until the pressure is reduced to below atmospheric pressure.
• Injection. Once the correct pressure has been reached, a pre-measured amount of concentrated (59 percent) hydrogen peroxide is pumped from the cassette into the valve vaporizer bowl and vaporized into the chamber.
• Diffusion. In the diffusion stage, hydrogen peroxide vapor is driven into the small crevices and lumens of the devices in the chamber. The chamber returns to atmospheric pressure to accomplish this.
• Plasma. A vacuum decreases the pressure and radio frequency energy is radiated within the chamber from the electrode screen. The RF energy ionizes the hydrogen peroxide, creating hydrogen peroxide gas plasma and generating free radicals and other chemical species, which destroy organisms.
• Repeat. The injection through plasma phases are repeated.
• Vent. At the end of the second sequence, the RF is turned off. Air is vented into the chamber through antibacterial high-efficiency particulate air filters, returning it to atmospheric pressure.

At the sterilization cycle's end, a 10-second continuous audible alarm sounds, alerting the operator that the cycle is complete and items can be removed from the sterilizer. The printer prints a summary of the cycle parameters. The operator can then open the door and remove the sterilized items ' because there are no toxic residues, the items can immediately be used.

As with all devices, only those devices that meet the clearances for the LTGP system or are cleared by the device manufacturer should be processed in this type of system.

An important safety consideration: 59 percent liquid hydrogen peroxide (nominal solution) is potent stuff. Avoid contact with skin and eyes. Skin contact can cause tingling, irritation or burning and a white discoloration; eye contact can cause tissue damage.

Ozone ' easy and efficient
Ozone sterilization was cleared for use in the United States in 2004. This type of sterilizer uses oxygen that is subjected to an intense electrical field that separates oxygen molecules into atomic oxygen. The atomic oxygen then combines with other oxygen molecules to form ozone inside the 4.3-cubic foot machine. At the end of the cycle, oxygen and water vapor safely vent into room, leaving no toxic residues.

This method is easy to use; each of the four cycle parameters ' vacuum, humidification, ozone injection/exposure and ventilation ' runs twice.

The plusses: Total cycle time is just four hours, and installation requires only an electrical outlet, oxygen source and demineralized water for humidification. But if you're going to use ozone, the sterile processing room must be well-ventilated, with at least 10 air exchanges per hour.

Liquid chemicals ' a variety of ways to soak
You have several options to choose from in this category.

• Activated glutaraldehyde. This is a liquid high-level disinfectant that will achieve sterilization with prolonged soak times (this solution is used mainly with immersible items). Activated glutaraldehyde is generally used for HLD of flexible and rigid scopes because it is non-corrosive to instruments containing plastic, metal and lenses, and it's appropriate for long lumens.

You must thoroughly pre-clean devices for activated glutaraldehyde to work properly, and you must ensure that the solution makes contact with all surfaces of the device to achieve HLD.

It has both a shelf life (printed on the jug and determined by the manufacturer) and a use life ' check the instructions on the jug or check with your manufacturer for specifics, as different formulations have different lives. One formulation adds a buffer to make the solution last longer. Because the minimum effective concentration of the solution can fall below the required level (even before the stated expiration date), you should test the efficacy of the solution before each use. Purchase test strips from the solution manufacturer, as they will be most accurate for determining the minimum effective concentration. The disinfectant's use life can be adversely affected by soils, temperature and in-use dilution (by leftover rinse water).

The minimum soak time is determined by the disinfectant manufacturer and is often affected by temperature; check with the manufacturer of your solution for recommendations.

• Glutaraldehyde. The 2 percent alkaline solution is effective against all vegetative bacteria, viruses, TB and fungi ' but it can be toxic, so you must thoroughly rinse every surface exposed to it to remove all residues. That means performing three separate rinses, each time in new water ' you should not reuse the water. Use only sterile water for cameras and rigid scopes; the quality of the rinse water can affect potential recontamination of the device.

You must take precautions when using glutaraldehyde. First, you should use the solution only in a limited-traffic area.

Second, proper ventilation is a must, as the solution's vapors can irritate the respiratory tract. You might want to use a local exhaust hood to capture vapors during processing. The hood should be connected to a non-recirculating exhaust system that leads to your facility's exterior. Self-contained systems are also available. Either way, you should monitor the hood for efficacy.

Third, proper personal protective equipment is needed, as the liquid can be a skin irritant. Wear eye shields, a fluid-resistant mask (for liquid not fumes), butyl or nitrile rubber gloves (no vinyl or neoprene) and a polyethylene gown with long sleeves. Store the solution covered in a basin.

OSHA has not set a ceiling limit for employee exposure to glutaraldehyde, but this does not mean the fumes are safe for uncontrolled breathing. OSHA defers to the American Conference of Governmental and Industrial Hygienists, which recommends that at no time should the ceiling limit of 0.05 ppm be exceeded. Monitor employees for exposure to glutaraldehyde fumes; in small- and medium-sized centers, that means hiring an outside service that analyzes air and gases.

You should also have a spill plan in place in the event the solution is spilled. For disposal, check the local or state regulations; they usually recommended that you dilute the glutaraldhyde with copious amounts of running water. Dispose of containers per label instructions

• Orthophthaldehyde (0.55 percent). The newest high-level disinfectant is orthophthaldehyde, a non-glutaraldehyde product that is non-toxic and has a label claim for a 12-minute soak time for high-level disinfection. It now has a five-minute HLD claim, but only when used in an automated endoscope reprocessor that can sufficiently elevate the temperature of the solution. The five-minute claim does not apply to OPA if you use it without an AER.

You do not need to monitor employees' exposure, but they should use OPA in a well-ventilated area while wearing proper PPE. Staff might have to double-glove because the product stains protein (and therefore will stain the skin). This is an advantage because if the device is not properly cleaned, the protein soils will stain gray or black, alerting you to the need to re-clean and reprocess the device before putting it back into circulation. This product is non-forgiving, so you must use it as directed. OPA has a 14-day use life, and any unused portion can remain in the original bottle for 70 days.

• Peracetic acid. This liquid sterilization method has been has been available since 1988 as an alternative to EtO. As with all other processes, you must first thoroughly clean items. You can only use a peracetic acid system with immersible items (it's a wet system). There is no packaging; it is a just-in-time, point-of-use system.

Peracetic acid systems use a powdered concentrate diluted with water inside the processor chamber. Before you initiate a cycle, insert a container of peracetic acid (each is a single-dose container). At the end of the cycle, the person removing the items from the reprocessor should verify that the container is empty, indicating the sterilant was used.

The cycle time is 30 minutes to 40 minutes, with 12 minutes' exposure to the peracetic acid. At the end of the sterilization cycle, four post-rinses occur.

You should monitor and document peracetic acid systems daily. Before using it for the first time each day, perform a diagnostic test. Check and change pre- and post-sterilization water filter routinely. You should have a spill plan for peracetic acid in place.

Considerations for choosing
When deciding which steam sterilization alternative to use in your facility, take into account more than simply the types of surgical instrumentation you'll need to process. Research and visit other facilities using each type of system before buying. Ask them these six questions:

• Would you purchase it again?
• Is it easy to use?
• Does it adversely affect devices?
• Have your costs increased?
• What is the manufacturer's service like?
• How difficult was it for the staff to learn to operate the system?

You should also consider space and cost; space requirements can be significant, and you want to know what the process will cost in both capital and operational expense.

It's also important to involve other members of the team in buying this type of equipment. Often engineering or construction services will work with the vendor to meet the requirements for installation. You should do this before you finalize a purchase to reduce implementation problems.

After you've completed your extensive research and you move forward with a purchase, outline an education plan to help the staff learn the technology. Most vendors will give extensive in-service training to all shifts in the sterile processing department and the OR before and during the implementation process.