Since January of 2003, many BMETs have helped me put together this series of articles that hopefully have shared information that you needed in preparing for the certification exam. From time to time we have made mistakes in what was presented, sometimes caused by brain cramps on my part but other times by just having outdated information as a source. I have been collecting articles on medical devices since 1964, and unfortunately, I have sometimes chosen outdated reference articles as a source. For this I apologize and promise to try to do better as this series continues in future issues. I also ask you to send in suggestions on topics you would like to see addressed in this series.
In August, we made some serious mistakes and were brought to task by Christopher Nowak, CBET; John Heidebrecht, BMES; and Rocky Jackson, BMES, from St John’s Health System, Springfield, Mo. Below is an excerpt from their letter clarifying and correcting some of what was said in the August article.
“We would like to identify the process of sterilization so the technical reader will understand the appropriate steps handlers must take to ensure the success of sterilized devices. Initially, contaminated instrumentation arrives to be processed and is subjected to a physical and chemical cleaning process to remove such things as bioburden and other debris. This process may involve such steps as hand cleaning as well as sonic cleaning, which includes some type of enzymatic solution. These steps precede any automatic washing process that achieves high-level disinfection for the safety of the staff handling the devices during the assembly process of the surgical instrument sets. After this physical and chemical cleaning process, the devices and instruments are ready for the sterilization process.
“The sterilization process can involve steam, ETO, plasma, ozone, or chemical as described in the 24×7 article (ICC Prep, August 2006). Common sizes of devices for steam sterilization are: 16 x 16 inches, 20 x 20 inches, and 24 x 36 inches. Depths of these devices range from 26 inches to 60 inches.The article pointed to a 30-inch vessel size, which appears to be nonexistent. The chambers are manufactured from mild steel and lined with nickel alloys. Some newer chambers manufactured today are stainless steel. The door configuration for any of these devices is subject to the layout of the facility central supply department. Most devices are only single door, and some are double door, again depending on the room layout.
“Steam sterilizers are capable of running 250°F at approximately 20 PSI to 270°F at approximately 30 PSI loads, with most running at the later specification. The authors (David Harrington, PhD, and John Downs) stated that the pre-Vac cycle is designed to speed the sterilization process, when in fact it lengthens the time of sterilization due to four-pulse cycles to remove residual air in the chamber, which acts as an insulator. Most steam sterilizers used throughout the United States utilize a water injector to develop a vacuum rather than a vacuum pump as described in the article. The water-injector process uses a venturi effect to create a vacuum in the chamber to complete the purge of any trapped air in the chamber. This type of water-injection process has an initial lower cost of ownership due to the large capital acquisition expense of a device with a vacuum pump.
“The authors (David Harrington, PhD, and John Downs) go on to talk about wet loads and describe the common cause to be venting or vacuum systems. While this is true, most wet loads are caused by process errors from the operator. Instrumentation must be dry and properly packaged. Cloths or wicks are inserted between metal pans to prevent puddling caused by condensed steam. As good as vacuum systems are, most sterilizers cannot remove puddles in the time frame of the process. Metal containers placed above wrapped or pouched items will cause puddling.
“The authors (David Harrington, PhD, and John Downs) describe ‘cold sterilization’ as closer to pasteurization; however, sterilization is the process of destroying all forms of microbial life on inanimate surfaces versus pasteurization, which is described as a process to achieve a log reduction in the number of viable organisms, reducing their number so they are unlikely to cause disease. Therefore, sterilization, whether cold or heated, should never be referred to as pasteurization.
“Flash sterilization is a process used typically for emergent situations, such as dropped instrumentation. It can be a 250°F load or a 270°F load, depending on devices for sterilization,” the letter concludes.
On Another Note
In the ICC Prep article on mammography (July 2006), it was pointed out that on most systems when automatic exposure control (ACR) is used, both the kV and mAs changes not just the mAs, as stated in the article. It also refereed to the ACR Mammography Quality Control Manual for better explanations on the film QC.
As we move forward with this series of articles, we hope to catch the mistakes or oversights that occur. If we do not, please let us know.
Again, thank you for all the comments, both good and bad, over the last 4 years on this series. If you are an expert in an area, please consider doing an article to help your peers in the business expand their knowledge. By working together, we can really help make health care the very best and keep costs under control.
David Harrington, PhD, is director of staff development and training at Technology in Medicine (TiM), Holliston, Mass, and is a member of 24×7’s editorial advisory board. For more information, contact us at [email protected]
