CS Questions CS Answers

What exactly is gas plasma?

with Ray Taurasi

Editor’s Note: CS Questions, CS Answers is a feature of Healthcare Purchasing News in which we offer practical solutions to questions and problems that are common to many central service and sterile processing departments. HPN welcomes your participation in this inter-active feature. 
To ask a question, e-mail it to cwerner@ hpnonline.com, phone it in to Curt Werner, HPN editor, at (941) 927-9345, or mail it to HPN CS Questions, 7650 S. Tamiami Trail, Suite 10, Sarasota, FL 34231. Names and hospital identification will be withheld upon request.

CS Question: What exactly are gas plasma and ozone how do they sterilize medical products? What are the advantages and disadvantages of their use in the hospital setting?

CS Answer: First, let’s discuss gas plasma sterilization. Plasma is a fourth state of matter which is distinguishable from liquid, solid, or gas. In nature, plasma is widespread in outer space. The aurora borealis, or “northern lights,” is an example of naturally occurring plasma. A reactive cloud of ions, electrons and neutral atomic particles result from a low-temperature glow discharge plasma. The plasma state of matter can be produced through the action of powerful electric or magnetic fields. The free radicals in the plasma cloud can interact with cell membranes, nucleic acids and enzymes, causing disruption in cell activities and destruction of microbial life. 

The advantages of gas plasma sterilization include its ability to provide safe, non-toxic, dry, low-temperature sterilization in about one hour. By-products of plasma sterilization are primarily water and oxygen. Because these by-products are harmless, there is no need for aeration or environmental hazard concerns.

The disadvantages of gas plasma sterilization are that it may not penetrate well, especially in channels or devices designed with long lumens. In addition, the gas plasma sterilization method may corrode some materials and cannot be used on paper, cellulose or linen. An additional drawback to plasma sterilizers is their small chamber.

Now, let’s discuss ozone sterilization. Ozone, a different molecular form of oxygen, can be found in the upper atmosphere, where it serves to protect us from the damaging effects of ultraviolet rays. Ozone has been used as a disinfectant for drinking water and as a sterilant in the food industry.

In healthcare, ozone is used in sterilizers. In a sterilizer, ozone is produced as a by-product when an electrical charge is added to oxygen. The resultant ozone gas is humidified to 70 percent to 90 percent humidity and is dispersed into the sterilization chamber where it flows continuously throughout the sterilization cycle. Sterilization is achieved through oxidation of microbes. Following the sterilization cycle, the ozone is catalytically converted back to oxygen.

The advantages of ozone sterilization include its low temperature (25°C) and rapid cycle time low concentration requirements. Ozone is non-toxic and environmentally friendly. The disadvantages of ozone sterilization are its limited penetrability and since the chamber humidity is high (75 percent to 90 percent relative humidity), natural gum rubber products and some plastics may degrade and most metals will corrode in time.

CS Question: We are about to begin a renovation project for our sterile processing department that includes the replacement of our sterilizers. I am uncertain what to do about ethylene oxide sterilization and if I should replace the units or discontinue this method of sterilization. I am concerned that EO may be on its way out and will not be available to hospitals in the future. What advice can you offer?

CS Answer: As a sterilant, EO has many advantages. It is effective against all forms of microbes, easily passes through closely-woven material, will not corrode metal, is readily available and may be used on a wide variety of products.

There are also disadvantages in using ethylene oxide. It is expensive and does not work quickly. Products made of porous materia1s absorb it and cannot be used for several hours after they’ve been sterilized. Ethylene oxide is flammable and highly toxic. The effects from overexposure can range from minor skin and respiratory irritation, headaches or nausea to more severe conditions such as cancer, reproductive difficulties or chromosomal alteration. Safe work habits, adequate ventilation and careful monitoring can limit the effects of overexposure. 

Although not ideal, ethylene oxide sterilization is still considered the most efficient low-temperature sterilization process currently available. It is very unlikely that the use and availability of EO will be significantly curtailed in the near future.

While there are a myriad of low-temperature alternatives to ethylene oxide that have potential, they do not share its span of application. Some facilities that made the decision to discontinue their use of EO have found that the alternative methods they adopt were unable to meet all of their needs. As a result, some institutions have reacquired an ethylene oxide sterilizer while other institutions have found it necessary to outsource their EO sterilization to other hospitals or commercial sterilization facilities.

The decision to replace and or discontinue the use of EO should only be made after a careful analysis of the product mix and the volume of devices requiring low temperature sterilization in your hospital. Each product or medical device should be evaluated to determine its compatibility and capability of being processed through alternative sterilizing equipment. 

It may be possible that based on size, specialization and inventory, some hospitals may choose an alternative method to ethylene oxide. But for many hospitals, especially larger, more complex institutions, this will not likely be the case. Based on your careful evaluation and assessment you might decide to use a combination of one of the alternative methods and reduce the volume of ethylene oxide-processed goods with an eye toward decreasing the number and/or size of your facility’s EO units. 

HPN

Ray Taurasi is director of business development for Case Medical Inc., Ridgefield, NJ. His healthcare career spans more than three decades as an administrator, educator, technologist and consultant. He is a past president of IAHCSMM and has served on and contributed to many national committees with a myriad of professional organizations, manufacturers, corporations and prestigious healthcare networks. Taurasi has been a faculty member of numerous colleges teaching in the divisions of business administration and health sciences. In addition to this column he has authored several articles and has been a featured speaker on the international scene.

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