Selection of the “right” sterilization or disinfection process, or technology, for reprocessing a specific type of reusable instrument may not always be straightforward. This is often because the instrument is damaged by heat and, therefore, cannot be easily and cost-effectively sterilized using pressurized steam.
For many types of reusable heat-sensitive instruments capable of transmitting diseases during a medical procedure, low-temperature sterilization technologies and robust disinfection processes were developed. To be sure, selection of the appropriate reprocessing technology is crucial to quality, safety and the prevention of healthcare-associated infections (HAIs).
In general, the documented risk of infection associated with the reuse of a instrument (i.e., low, moderate, high), contaminated with potentially pathogenic microorganisms, dictates whether its disinfection or sterilization is required to prevent disease transmission.
The following strategy explains how to select an appropriate reprocessing procedure for a specific type of reusable medical instrument.
Step 1. Determine the reusable device’s “classification.”
The first step in this process is to determine whether the instrument is classified as “critical,” “semi-critical,” or “non-critical.” Table 1, below, may be used to simplify this determination.
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Table 1: A widely accepted classification scheme for medical instruments.
A. Critical instruments penetrate sterile tissue, enter the vasculature, or contact the patient’s blood.
- Examples include cardiac catheters, biopsy forceps, and implants.
B. Semi-critical instruments, in contrast, are limited to contacting mucous membranes (e.g., those of the gastrointestinal [GI] tract, the pulmonary tract, or the oral cavity) or non-intact skin.
- Examples include GI endoscopes, “ENT” (ear-nose-throat) endoscopes, cystoscopes, and the blades and handles of rigid laryngoscopes.(1-4)
- The risk of infection associated with instruments in this category, while still potentially significant, is less than that of critical instruments.
Click here to read Dr. Muscarella’s related blog “The Reprocessing of Sheathed “ENT’ Endoscopes and Cystoscopes.”
Click here to read Dr. Muscarella’s related blog “On Reprocessing Skin Electrodes.”
C. Noncritical instruments, on the other hand, do not directly contact the patient, or only contact the patient’s intact skin.
- Examples include blood pressure cuffs, stethoscopes, and bedpans. Other examples of non-critical devices include environmental surfaces, such as walls, floors, and sink tops.
- Non-critical instruments pose the least, and a low, risk of infection if contaminated at the time of their use and contact with patients.
Click here to read Dr. Muscarella’s related blog “Decontamination of CPR Manikins.”
[Are you in the market to buy a CPR manikin? Click the link.]
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Step 2. Understanding the differences between sterilization and the three levels of disinfection.
The next step in this process is to understand the differences between disinfection and sterilization.
Whereas sterilization is an absolute term that may be used to refer to processes that destroy all types of infectious agents, disinfection is a relative term, and processes that achieve it are classified into one of “three levels,” depending on their relative effectiveness. The higher the level of disinfection, the more effective the process.
Click here to read about a auditing program developed by Dr. Muscarella specifically designed to prevent infection-control breaches and associated infections (HAIs).
Presented another way, the more resistant the microorganism, the higher the level of disinfection (or sterilization) required to destroy it. Table 2, below, explains the differences between the three levels of disinfection and sterilization.
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Table 2. The definitions, characteristics, and relative effectiveness of sterilization and disinfection’s three levels.
A. Processes that achieves sterilization:
- are absolute, meaning they destroy all microorganisms, including bacterial endospores;
- are sporicidal, tuberculocidal, virucidal, fungicidal, and bactericidal;
- use bacterial endospores as biological indicators; and
- are regulated by the Food and Drug Administration (FDA).
Agents that achieve sterilization include pressurized steam, ethylene oxide gas, hydrogen peroxide plasma. Sterilization is used primarily to prevent reusable critical instruments from transmitting disease during their reuse.
B. Processes that achieve high-level disinfection (or, “HLD”):
- destroy all pathogenic microorganisms, including some types of (but not all) bacterial endospores during relatively short exposure times;
- typically destroy high numbers of bacterial endospores during long exposures times;
- are sporicidal (limited), tuberculocidal, virucidal, fungicidal, and bactericidal;
- use mycobacteria as indicators of effectiveness; and
- are regulated by the FDA.
Agents that achieve HLD include 2% glutaraldehyde, 7.5% hydrogen peroxide, and 0.2% peracetic acid. HLD is used primarily to prevent reusable semi-critical instruments from transmitting disease during their reuse.
C. Processes that achieve intermediate-level disinfection (or, “ILD”):
- destroy many types of microorganisms including mycobacteria;
- are not sporicidal (note: in general, processes that achieve high-level disinfection are ordinarily sporicidal, like sterilization, but, unlike sterilization, may require extended exposure times (e.g., 32 hours) to destroy bacterial endospores);
- are tuberculocidal, virucidal, fungicidal, and bactericidal;
- may use mycobacteria and/or viruses as indicators of effectiveness; and
- are regulated by the Environmental Protection Agency (EPA).