SPD High-Level Disinfection 2 — Questions and Answers
Question 1: Which Spaulding classification level requires high-level disinfection as the minimum reprocessing standard?
- Critical items
- Semi-critical items (Correct answer)
- Non-critical items
- All classifications equally
Correct answer: Semi-critical items
Semi-critical items that contact mucous membranes or non-intact skin require at least high-level disinfection, which kills all microorganisms except high numbers of bacterial spores.
Semi-critical items in the Spaulding classification contact mucous membranes or non-intact skin. Examples include respiratory therapy equipment, endoscopes, laryngoscope blades, and vaginal/rectal probes. High-level disinfection eliminates all vegetative bacteria, fungi, viruses, mycobacteria, and most bacterial spores. While sterilization is preferred when possible, HLD is the minimum acceptable standard for semi-critical items that cannot withstand sterilization conditions.
Question 2: What is the minimum effective concentration (MEC) of a high-level disinfectant?
- The maximum concentration recommended by the manufacturer
- The lowest concentration of active ingredient at which the solution still achieves high-level disinfection (Correct answer)
- The concentration at which the solution becomes toxic
- The concentration measured when the solution is first prepared
Correct answer: The lowest concentration of active ingredient at which the solution still achieves high-level disinfection
MEC is the lowest concentration at which the disinfectant maintains its germicidal effectiveness and must be verified before each use with chemical test strips.
The Minimum Effective Concentration is the threshold below which a high-level disinfectant can no longer reliably achieve its claimed level of microbial kill. HLD solutions lose potency over time through chemical degradation, dilution from rinsing of wet items, and organic matter neutralization. Before each use, the MEC must be verified using manufacturer-provided chemical test strips. If the test indicates concentration has fallen below the MEC, the solution must be discarded immediately regardless of its use-life expiration date.
Question 3: What is the most common high-level disinfectant used for flexible endoscope reprocessing?
- Alcohol (70% isopropyl)
- Glutaraldehyde (2%) or ortho-phthalaldehyde (OPA) (Correct answer)
- Hydrogen peroxide (3%)
- Quaternary ammonium compounds
Correct answer: Glutaraldehyde (2%) or ortho-phthalaldehyde (OPA)
Glutaraldehyde and OPA are the most widely used high-level disinfectants for heat-sensitive devices like flexible endoscopes due to their broad-spectrum efficacy and material compatibility.
Glutaraldehyde (2.0-3.4%) and ortho-phthalaldehyde (OPA, 0.55%) are the predominant high-level disinfectants for flexible endoscope reprocessing. Glutaraldehyde provides broad-spectrum antimicrobial activity with 20-90 minute soak times. OPA offers advantages including faster kill times (12 minutes at 20°C), less irritating fumes, and no activation required. OPA's disadvantage is that it stains proteins gray. Other FDA-cleared HLD agents include peracetic acid, hydrogen peroxide-based formulations, and hypochlorous acid systems.
Question 4: What is the required final rinse procedure after high-level disinfection?
- Rinse with tap water once
- Rinse thoroughly with sterile, filtered, or high-quality water to remove all chemical residue (Correct answer)
- Air dry without rinsing
- Wipe with a dry cloth
Correct answer: Rinse thoroughly with sterile, filtered, or high-quality water to remove all chemical residue
After HLD, items must be rinsed thoroughly with sterile or filtered water to remove all disinfectant residues that could cause tissue irritation or chemical burns.
Post-HLD rinsing is critical for patient safety and must use water of appropriate quality. AAMI ST91 recommends sterile water for the final rinse of items contacting sterile body cavities, or at minimum bacteria-free filtered water (0.2 micron) for items contacting mucous membranes. Tap water is generally not acceptable as it may introduce waterborne organisms to a device that was just disinfected. After rinsing, items should be dried with forced air and alcohol rinse to facilitate rapid drying.
Question 5: What is the purpose of leak testing a flexible endoscope before high-level disinfection?
- To check for electrical problems
- To detect perforations or seal failures that would allow fluid ingress and damage internal components or harbor organisms (Correct answer)
- To verify the scope is the correct model
- To measure the scope's internal diameter
Correct answer: To detect perforations or seal failures that would allow fluid ingress and damage internal components or harbor organisms
Leak testing detects breaches in the endoscope's protective outer sheath that could allow cleaning solutions or body fluids to penetrate and damage components or create contamination reservoirs.
Flexible endoscopes have a complex internal architecture protected by an outer sheath. Leak testing must be performed before every reprocessing cycle because a damaged sheath allows solutions to seep into internal spaces, creating chemical damage and ideal environments for microbial growth. Testing involves pressurizing the scope's interior while submerged and watching for bubble streams. A failed leak test requires immediate removal from service for manufacturer repair.
Question 6: How should high-level disinfected items be stored if not used immediately?
- In any available cabinet
- In a clean, dry, ventilated area following facility policy for maximum storage duration, with forced-air drying of channels (Correct answer)
- On the decontamination counter until needed
- In the original disinfectant solution for extended protection
Correct answer: In a clean, dry, ventilated area following facility policy for maximum storage duration, with forced-air drying of channels
HLD items should be stored in designated clean areas after thorough drying, as moisture promotes microbial recontamination during storage.
Storage of high-level disinfected items requires careful attention. Flexible endoscopes should be hung vertically in ventilated storage cabinets with channels disconnected to promote air circulation, stored with all valves removed, and kept in a designated clean area. SGNA and AAMI recommend that stored endoscopes be reprocessed if not used within a facility-defined timeframe (often 5-7 days). Drying cabinets with HEPA-filtered forced air significantly reduce recontamination risk.
SPD High-Level Disinfection 2
Which Spaulding classification level requires high-level disinfection as the minimum reprocessing standard?