Sterilization of Medical Equipment: Preventing Infections and Saving Lives
It is impossible to overstate the importance of sterilizing equipment and disinfecting surfaces in health care facilities. Sterilization techniques have saved countless lives and spared untold numbers of people the pain and suffering of post-surgical and other microbial infections.
Healthcare-associated infections (HIAs) are extremely common—the World Health Organization reports that hundreds of millions of patients are affected by HIAs each year worldwide.1 While the number of people affected is greater in developing countries, infection rates in developed countries do not trail far behind. It is clear that diligent sterilization and disinfection are absolutely essential in any healthcare environment.
Healthcare facilities use a
variety of disinfectant solutions to sterilize equipment, as well as autoclaves, the latter which work by exposing medical supplies and devices to high pressure steam to sterilize the equipment.
We’ll take a closer look at some common disinfecting and sterilization methods used today, and their impact on healthcare.
Disinfecting & Sterilization Methods
The many products and methods used to disinfect and sterilize equipment and surfaces include (but are not limited to):
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Chemical Disinfectants
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Sterilization Methods
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- Steam Sterilization (Autoclave)
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- Ethylene Oxide “Gas” Sterilization
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- Hydrogen Peroxide Gas Plasma
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- Peracetic Acid Sterilization
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Additional sterilization methods include exposing equipment to UV radiation and gamma radiation, as well as pasteurization. We’ll go into more detail about some commonly used disinfecting and sterilization methods below.
Sterilization Methods
- Ethylene Oxide (EtO) Sterilization: Ethylene Oxide is a colorless flammable gas that has been used for decades to sterilize surgical equipment. Despite decades of advances in sterilization, EtO remains a preferred method of sterilization due to its virucidal, bactericidal, and sporicidal effectiveness. One of EtO’s main advantages is that it can be safely used on virtually all medical equipment. To sterilize equipment with EtO, the item is placed inside a vacuum-filled chamber, and a mixture of ethylene oxide and nitrogen is fed into the chamber. An important part of the EtO sterilization process involves “aeration” of the gases to allow EtO residues to desorb from the treated equipment—important because EtO has toxic properties. Ethylene Oxide is considered a carcinogen and can cause headaches, nausea, dizziness, and vomiting if not handled carefully. Provided the EtO sterilization process is performed correctly, it is a safe and effective method.
- Steam Sterilization: Steam is a cost-effective, widely used natural sterilization method. There are several advantages of using steam sterilization (in an autoclave, for example). Steam is non-toxic, it kills spores, it is cost-effective, and the sterilization cycles are fast. Care must be taken when using an autoclave to ensure the steam does not become tainted with impurities, and that any equipment or tools placed inside the unit can withstand the heat and pressure to which it will be subjected.
- Particle Accelerators: Using a beam of electrons and X-rays in a particle accelerator kills germs on contact. This method is especially useful for medical supply manufacturers prior to the final packaging of products. Syringes, surgical tools, bandages, and other medical supplies and their packaging need to be absolutely sterile when a product goes out. Particle acceleration is ideal for sterilizing several different materials within the same package (e.g. medical supplies and their packaging) without damaging any of the materials. Heat sterilization, for example, may be effective at sterilizing a metal scalpel, but it will also damage the product’s packaging.
Disinfectant Methods
- Chlorine and Chlorine Compounds: Chlorine compounds, such as sodium hypochlorite (liquid) and sodium calcium hypochlorite (solid), are frequently used as disinfectants, as they have a broad spectrum of antimicrobial activities. They are also cost-effective, fast acting, and leave no toxic residues. While the exact mechanism by which chlorine kills microorganisms is unknown, there are a number of possibilities: the solution may cause loss of intracellular contents in microbes, it may cause oxidation of respiratory components, or it may cause breaks in DNA or depress DNA synthesis, along with other possibilities. Whatever the mechanism, chlorine is a proven disinfectant.
- Formaldehyde: Used as a disinfectant in both its liquid and gaseous forms, formaldehyde is an effective bactericide, tuberculocide, fungicide, virucide, and sporicide (in aqueous solution form). It is a potential carcinogen and therefore has a time-limited exposure restriction, per OSHA. Formaldehyde can cause asthma-like respiratory problems and skin irritation with long-term exposure to low levels, and can be fatal with high-level exposure. For these reasons formaldehyde has limited uses in the healthcare industry. Its uses in healthcare are generally to prepare viral vaccines, such as influenza, and to preserve anatomic specimens.
Sterilizing Practices
To ensure that sterilization methods are carried out effectively, healthcare personnel should carry out the cleaning, disinfecting, and sterilization of medical equipment in a centralized processing department consisting of decontamination, packaging, sterilization, and storage areas (at a minimum). A centralized facility will help prevent patient infections, minimize risks to staff, and prolong the life of medical equipment.
Physical barriers should separate the different areas in order to minimize the risk of cross contamination. A comprehensive program to ensure staff is trained to carry out proper methods of cleaning and sterilization is also important—staff members will need to be trained on all aspects of the process, including operating equipment, wrapping instruments, loading and operating sterilizing machines, and monitoring the entire process.
Cleaning
Items should be cleaned prior to sterilization using water or detergents in order to remove foreign materials that could interfere with the sterilization agent. For example, surgical instruments are generally presoaked or prerinsed to prevent blood or tissues from drying on the instruments. Mechanical cleaning machines, such as dishwashers or ultrasonic cleaners, can help improve the effectiveness of cleaning and reduce exposures to workers.
Monitoring
A combination of mechanical, chemical, and biological indicators should be used to monitor the sterilization process. Mechanical monitors provide time, temperature, pressure, and other information about the sterilization process. Chemical monitors indicate that an item has been exposed to the sterilization process—usually with heat—or chemical-sensitive inks that change colors when certain parameters (such as temperature) are present. Biological indicators measure the sterilization process directly by indicating that the highly-resistant organism (the bio-indicator) has been inactivated. The implication is that if the most resistant organism has been inactivated, other potential pathogens have likely been killed as well.
Disinfecting and sterilizing equipment and surfaces in healthcare settings is essential to prevent infections and the spread of disease. A comprehensive sterilization plan can save lives as well as hundreds of millions of dollars in associated costs every year.
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Make sure you have the right equipment you need to sterilize your medical equipment.
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