Infection Control Today - 12/2003: Chemical Sterilants

Chemical Sterilants Revolutionize Decontamination

By Kathy Dix

Sterile processing departments (SPDs) have an array of choices for the method of sterilization, but deciding which approaches to use often comes down to the chicken or the egg argument although they all have the same purpose, each systems users will always have its proponents and detractors.

Gas and heat were the primary methods of sterilization for many years. Charles Hughes, general manager at SPS Medical, a sterilizer-testing laboratory, says, By 1957, when I was born, an EO (ethylene oxide) gas sterilizer became available by the Castle Sterilizer Company. When I left school teaching years ago, I went to work for Castle Sterilizer. I spent a lot of evenings in their library learning, and found it fascinating that EO gas sterilized the fuel propellant at NASA that lowered the first lunar module down on the moons surface. They sterilized it because they did not want to contaminate the lunar surface with anything that was manmade or from the Earth.

In 1988, STERIS SYSTEM 1 was approved; in 1993, ASPs STERRAD (which uses hydrogen peroxide) was approved. The hydrogen peroxide system, like peracetic acid, lessened reprocessing time. The hydrogen peroxide system cycle lasted through a 45- or 50-minute cycle, while the peracetic acid system requires 30 minutes. Hughes compares this processing time to the two- or four-hour EO cycle, which is followed by eight to 12 hours of aeration.

When you think of whats been used, EO gas has been the number one product still, Hughes says. He clarifies, however, that the shorter-duration chemical reprocessors have made significant inroads into hospitals.

Prices differ significantly depending on the method, Hughes points out. The STERIS system began retailing for $16,000, while the STERRAD system entered the market costing $110,000, and the newly approved TSO3 ozone sterilizer is expected to carry a similar price tag. This device creates its own sterilant using medical-grade oxygen, water and electricity, leaving oxygen and vaporized water as its emissions.

Now, youd think everybody would stick with STERIS SYSTEM 1, but the disadvantage is that its a liquid sterilizer, and all the devices have to be immersible. Thats not the case with EO gas, STERRAD or with the ozone sterilizer, says Hughes. They really are the only options for a hospital industry uses radiation, which is considered a low temperature process as well. Theres two types of radiation, but a radiation facility is not something thats considered practical for a hospital, nor is it technically an FDA-approved process.

Hughes references a 1999-2000 study that reports that the sterilizer market is a $100 million industry, with an additional $20 million in sterilant consumables.

In an aside, Hughes disputes the rumor that EO is being phased out. At least 50 percent of hospitals still do have gas. People who actually work with it will tell you they hate that vicious rumor, because it will continue to be around for quite some time, he affirms.

The Truth About Liquid Chemical Sterilants

There is no perfect liquid chemical germicide. Some are better than others; it depends on the use, says Martin S. Favero, PhD, director of scientific and clinical affairs at Advanced Sterilization Products. Favero notes that for endoscopes specifically, Theres been a huge shift away from glutaraldehyde to orthophthalaldehyde (OPA) for the simple reason that people dont like to fiddle with OSHA, and they want to get away from the irritation that the staff is experiencing when they handle glutaraldehyde.

Glutaraldehyde was introduced in 1963; that particular sterilant has excellent materials compatibility attributes, and thus lower repair costs than with many of the oxidative formulations. However, use of glutaraldehyde is accompanied by respiratory irritation and an unpleasant odor. These effects led to the adoption of OPA, which has a shorter cycle than glutaraldehyde.

With the formulations that are oxidative in nature (including peracetic acid and hydrogen peroxide), their advantages are that they are very good microbicides, and they also do not have any environmental issues, Favero points out. But the No. 1 disadvantage is that they have materials compatibility problems. Certain types of materials are reacted with, and theres both cosmetic and structural damage to instruments after repeated reusings.

The difference between gas sterilization and chemical is that some gas sterilization can be considered a terminal sterilization procedure, while all liquid chemical sterilization is considered non-terminal sterilization. The gas method sterilizes wrapped instruments; the chemical method, however, leaves the items unwrapped. Thus, the sterilized instrument needs to be used immediately; if it is stored instead, it is still unwrapped and therefore immediately contaminated, Favero adds.

The Benefits of Chemical Sterilants

In 1996, according to the Food and Drug Administration (FDA) web site, liquid chemical sterilants used for processing critical and semicritical medical devices were exempted from the definition of a pesticide under the Federal Insecticide, Fungicide and Rodenticide Act and are no longer regulated by the Environmental Protection Agency (EPA). FDA now has sole regulatory jurisdiction over liquid chemical sterilants and/or high level disinfectants used to process reusable critical and semicritical medical devices, says the site.

The chemical sterilant is a biocidal agent; its effective against viruses, its tuberculocidal, bactericidal, fungicidal and the granddaddy of all sporicidal. If you can prove that you can effectively kill spores, all the other organisms that are questionable have been killed long before you can kill spores. Those are the most difficult organisms to kill, says Terri Antonucci, senior director of clinical and customer education at STERIS Corporation.

Explains Stephen Loes, vice president of global marketing at STERIS, When youre looking at instruments costing $15,000 to $30,000, you dont necessarily want to have a large inventory of them. And when youre doing nine or 10 procedures a day, you want to be able to reprocess your scopes quickly and get higher usage of them. The greatest savings come from hospitals and surgery centers being able to reduce their inventory of very expensive equipment. Instead of one usage a day, theyre getting up to 10.

Liquid chemical systems are designed to be safe for costly temperature- sensitive devices, which include flexible and rigid endoscopes, cameras and light cords. You can sterilize anything thats immersible, anything that could withstand the temperature, which is between 50 and 56 degrees centigrade, notes Antonucci.

These systems may not all reside in the sterile processing department (SPD); instead, they may be located near the site of patient care. There certainly are several hundred SYSTEM 1 Sterile Processing Systems installed in SPDs, but they are especially useful at or near the site of patient care, so its an application that would be more in the operating room, or in the endoscopy lab, or in the ambulatory surgery department, or in the bronchoscopy lab, says Antonucci.

When asked who actually processes the devices, Loes says that staff nurses and technicians do it themselves. Its designed for nurses and technicians who work right in the surgical department to process the devices, Antonucci explains. They clean them, they prepare them according to the manufacturers recommendations, then when theyre trained on how to use the process theyre the ones who process the devices.

And when asked how the nurses feel about performing a non-traditional nursing task by reprocessing instruments, Loes says, They all felt it was a very valuable device for the OR and made them more effective. Theyre more concerned about infection in the patient.

It gives them a method of controlling their devices, Antonucci agrees. If they need it for the next case, they have it right at their fingertips. It hasnt left the department and theyre not having to make calls to see where it is. They have complete control over it.

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