11.1 Point-of-Use Treatment, Decontamination & Cleaning of Surgical Instruments

Point-of-Use Treatment, Decontamination & Cleaning of Surgical Instruments

Core Principle: In perioperative nursing and sterile processing, the clinical axiom remains absolute: "You cannot sterilize what is not clean." Terminal sterilization and high-level disinfection processes rely on direct, unobstructed contact between the sterilant and the instrument surface. If organic soil, cellular debris, lipids, or blood remain on surgical instrumentation, they form a protective microbial fortress known as biofilm, shielding underlying pathogenic vegetative bacteria, mycobacteria, and endospores from chemical and thermal destruction. Instrument processing begins not in the central sterile department, but intraoperatively at the sterile field in the operating room.

The Spaulding Classification Framework

Developed by Dr. Earle Spaulding in 1968 and continuously reinforced by the Centers for Disease Control and Prevention (CDC), the Association of periOperative Registered Nurses (AORN), and the Association for the Advancement of Medical Instrumentation (AAMI ST79), the Spaulding Classification System categorizes patient care devices and surgical instruments based on the degree of infection risk involved with their intended clinical use. This taxonomy dictates the minimum level of cleaning, disinfection, or terminal sterilization required before the device can be safely deployed on subsequent patients.

1. Critical Devices

• Anatomical Definition: Any instrument or device that enters normally sterile soft tissue, penetrates the vascular system, or contacts spaces through which blood flows or sterile body cavities (e.g., peritoneal, pleural, pericardial, subarachnoid, or joint spaces).
• Representative Ambulatory Instruments: General surgical scalpels, hemostats, needle holders, tissue forceps, laparoscopic trocars and graspers, arthroscopic shavers and osteotomes, ophthalmic microsurgical sets, orthopedic implants, and vascular access needles.
• Mandatory Processing Standard: Terminal Sterilization (complete destruction of all viable microbial life, including high numbers of resistant bacterial endospores).

2. Semi-Critical Devices

• Anatomical Definition: Any instrument or device that comes into contact with intact mucous membranes or non-intact skin, but does not ordinarily penetrate sterile tissue or enter the vascular system.
• Representative Ambulatory Instruments: Flexible fiberoptic gastrointestinal endoscopes, flexible bronchoscopes, rigid and flexible cystoscopes, laryngoscope blades, transesophageal echocardiography (TEE) probes, endocavitary ultrasound probes, and respiratory therapy or anesthesia breathing circuits.
• Mandatory Processing Standard: High-Level Disinfection (HLD) at a minimum, although terminal sterilization is strongly preferred whenever the device's heat and moisture tolerances permit. HLD kills all vegetative microorganisms, mycobacteria (e.g., Mycobacterium tuberculosis), lipid and non-lipid viruses, and fungal spores, but does not guarantee the eradication of high numbers of bacterial endospores.

3. Non-Critical Devices

• Anatomical Definition: Any device or equipment that comes into direct contact only with intact, unbroken patient skin, serving as a low-level vector for indirect transmission.
• Representative Ambulatory Instruments: Non-invasive blood pressure (NIBP) cuffs, pulse oximeter finger sensors, stethoscopes, pneumatic tourniquet cuffs, patient transfer boards, electrosurgical return electrode plates, and operating room positioning devices.
• Mandatory Processing Standard: Low-Level to Intermediate-Level Disinfection. Low-level disinfectants (e.g., quaternary ammonium compounds) kill most vegetative bacteria, some fungi, and enveloped (lipid) viruses. Intermediate-level disinfectants (e.g., 70% to 90% isopropyl alcohol, EPA-registered tuberculocidal phenolic or bleach solutions) inactivate mycobacteria and provide broader antiviral efficacy.

Intraoperative Point-of-Use (POU) Pre-Treatment Protocols

Point-of-use pre-treatment is an indispensable nursing responsibility executed by the scrub person (CST or scrub RN) and circulating registered nurse directly in the operating room. Dried blood, bodily fluids, and fat adhere tenaciously to surgical stainless steel, tungsten carbide, and titanium within 15 to 30 minutes of exposure to ambient operating room air. Once dehydrated, proteins cross-link, lipids solidify, and microorganisms rapidly synthesize extracellular polymeric substances (EPS) to produce mature biofilm.

┌────────────────────────────────────────────────────────────────────────┐
│         THE PROGRESSION FROM DRIED BIOBURDEN TO MATURE BIOFILM         │
├────────────────────────────────────────────────────────────────────────┤
│ 0 to 15 Minutes Intraop  ↳ Gross blood and protein coat instrument jaw │
│ 15 to 30 Minutes Intraop ↳ Proteins dehydrate; cross-linking begins    │
│ 1 to 2 Hours Post-Case   ↳ Microbes anchor; exopolysaccharides secrete │
│ 4 to 24 Hours Post-Case  ↳ Irreversible mature biofilm; 1,000x harder  │
│                            to penetrate with chemical disinfectants    │
└────────────────────────────────────────────────────────────────────────┘

Specific Point-of-Use Nursing Actions

1. Continuous Wipe-Down: During the surgical procedure, the scrub person should periodically wipe gross blood, bone fragments, and tissue debris from instrument tips, jaws, and box locks using a sponge saturated with sterile water.
2. Irrigation of Cannulated Lumens: Lumened, hollow, or cannulated devices (such as Frazier suction tips, Poole suction sleeves, lipoplasty cannulas, and laparoscopic irrigation shafts) must be flushed periodically during surgery with sterile water to prevent intraluminal clotted blood plugs.
3. Post-Case Enzymatic Application: Immediately upon completion of the procedure (prior to room breakdown), all used and opened instruments must be sprayed with a specialized enzymatic pre-treatment foam, gel, or humectant spray. These multi-enzymatic formulations contain proteases (break down proteins and blood), lipases (hydrolyze adipose tissue and marrow), and amylases (dissolve starches and carbohydrates). Pre-treatment humectants bind water molecules to instrument surfaces, halting evaporation and preventing bioburden desiccation during transit and waiting intervals.
4. Moist Packing Alternative: If commercial enzymatic sprays are unavailable, instruments should be covered with a surgical towel dampened with sterile water or sealed inside a dedicated moisture-retention plastic containment bag.

The Absolute Prohibition of Normal Saline (0.9% NaCl)

A critical and frequently tested clinical rule: Normal saline (0.9% sodium chloride) must NEVER be used to wipe, soak, flush, or rinse surgical instruments.

• Chemical Mechanism of Destruction: Surgical instruments are manufactured from martensitic or austenitic stainless steel, protected by an ultrathin, microscopic surface layer of chromium oxide ($Cr_2O_3$), known as the passivation layer. Sodium chloride dissociates into reactive sodium ($Na^+$) and chloride ($Cl^-$) ions in aqueous solution.
• Pitting and Crevice Corrosion: Highly electronegative chloride ions breach the passivation layer, attacking exposed iron molecules to create microscopic, localized electrochemical breakdown known as pitting corrosion. Pitting rapidly expands into deep, jagged micro-cavities within the steel matrix, particularly at high-stress junctures such as box locks, hinges, and ratchets.
• Clinical Consequences: Microscopic pits cannot be cleaned by mechanical brushes or ultrasonic cavitation; they harbor trapped blood, bacteria, and necrotic tissue that shield bacterial endospores during autoclaving. Furthermore, chloride pitting induces stress corrosion cracking, causing instrument jaws to snap or scissor blades to fracture inside patient operative wounds.

Biohazard Containment & Closed Transport Protocols

Following case completion and the final count, contaminated instruments must be transferred from the surgical suite to the central decontamination area under strict containment. In freestanding ambulatory surgery centers (ASCs), where central processing corridors may intersect with clean supply pathways or patient care corridors, improper containment creates severe airborne and contact exposure hazards.

Regulatory Transport Mandates (OSHA & AAMI ST79)

• Puncture-Resistant, Leakproof Containers: Soiled instruments must be transported in dedicated, rigid containers with secure, latching lids or enclosed transport carts that are completely leakproof on all sides and the bottom. Flexible open plastic bags or open mesh trays are strictly prohibited.
• Biohazard Labeling: The transport cart or rigid container must display an internationally recognized fluorescent orange-red Biohazard symbol or be clearly color-coded according to OSHA Bloodborne Pathogens Standard (29 CFR 1910.1030).
• Sharp Separation & Safe Loading: Sharp items (disposable scalpel blades, hypodermic needles, suture needles) must be counted, removed, and deposited into rigid sharps containers at the sterile field prior to instrument packing. Reusable sharp instruments (skin hooks, fine tenotomy scissors, sharp osteotomes) must be positioned in silicone-cushioned racks or oriented so that tips are protected and cannot puncture processing personnel.
• Instrument Weight & Delicate Staging: Heavy orthopedic retractors and mallets must be placed on the bottom of the transport container, while delicate microsurgical, ophthalmic, or fiberoptic instruments are staged in dedicated upper trays to prevent mechanical bending, misalignment, or shattered optics.
• Multi-Part Disassembly: Multi-piece instruments (such as modular laparoscopic trocars, take-apart graspers, and suction control valves) should be disassembled at the point of use according to the manufacturer's written Instructions for Use (IFU) so that internal surfaces are exposed to enzymatic pre-treatment.

The Decontamination Environment: Engineering Controls & PPE

The central decontamination room is the designated industrial bio-cleaning zone of the ASC. Because manual and automated washing generates hazardous aerosols containing bloodborne pathogens (Hepatitis B, Hepatitis C, HIV) and chemical vapors from detergents, stringent environmental engineering parameters and personal protective equipment (PPE) are legally mandated by ANSI/AAMI ST79, OSHA, and ASHRAE Standard 170.

Environmental Engineering Controls

┌────────────────────────────────────────────────────────────────────────┐
│         DECONTAMINATION SUITE ENVIRONMENTAL PARAMETERS (AAMI/ASHRAE)   │
├───────────────────────────────────┬────────────────────────────────────┤
│ PARAMETER                         │ MANDATED CLINICAL THRESHOLD        │
├───────────────────────────────────┼────────────────────────────────────┤
│ Air Pressure Differential         │ Negative pressure to clean areas   │
│ Air Changes per Hour (ACH)        │ Minimum 10 Total Air Changes / hr  │
│ Outdoor Air Exhaust               │ 100% Direct outdoor exhaust (no rec)│
│ Room Temperature                  │ 60°F to 65°F (16°C to 18°C)         │
│ Relative Humidity                 │ 30% to 60% relative humidity       │
│ Traffic Pattern                   │ Unidirectional: Dirty ➔ Clean only │
└───────────────────────────────────┴────────────────────────────────────┘

• Negative Air Pressure: Airflow must move inward from clean corridors into the decontamination suite, preventing airborne microbial contaminants and chemical fumes from escaping into prep-and-packaging, sterile storage, or OR suites.
• Exhaust Requirement: A minimum of 10 total air exchanges per hour, with all exhaust air vented 100% directly to the exterior of the building. Under no circumstances may decontamination exhaust air be recirculated back into the surgical facility's HVAC system.
• Temperature (60°F to 65°F / 16°C to 18°C): Kept cool to inhibit bacterial proliferation in wet sinks and to ensure the physical comfort of technicians working in full, impervious protective gear.
• Relative Humidity (30% to 60%): Maintains static electricity suppression while preventing condensation on walls and stainless steel surfaces.

Mandatory Personal Protective Equipment (PPE)

Staff entering the decontamination suite must don full biohazard personal protective gear before handling contaminated trays:

1. Impermeable Fluid-Resistant Gown: High-neck, long-sleeved gown made of liquid-barrier fabric with elastic wrists or thumb hooks, covering the torso and extremities down to the mid-calf.
2. Heavy-Duty Utility Gloves: Puncture-resistant, chemical-resistant nitrile or neoprene utility gloves with textured grips, extending well past the wrist over gown cuffs. Standard thin medical examination gloves (nitrile or latex exam gloves) are strictly forbidden for cleaning instruments because they are easily punctured by sharp burrs, osteotomes, and scissor tips.
3. Full Eye and Face Protection: A full-length face shield covering the forehead, eyes, nose, mouth, and chin, OR fluid-resistant surgical mask combined with wrap-around safety goggles with side shields. Standard prescription eyeglasses provide zero aerosol protection and do not meet OSHA criteria.
4. Liquid-Resistant Footwear: Fluid-impervious shoe covers worn over closed-toe, closed-heel non-slip work shoes, or dedicated waterproof rubber decontam boots.
5. Surgical Cap / Hair Covering: Completely enclosing all cranial and facial hair.

Manual Cleaning Protocols: The Three-Sink Configuration

Manual cleaning is the primary, foundational step for removing gross soil, lubricating joints, and flushing internal cannulas before instruments enter automated machinery. ANSI/AAMI ST79 strongly recommends a dedicated three-sink processing configuration ergonomically sized to accommodate standard surgical baskets.

┌────────────────────────────────────────────────────────────────────────┐
│         THE THREE-SINK MANUAL CLEANING CONFIGURATION                   │
├───────────────────┬───────────────────┬────────────────────────────────┤
│ SINK 1: SOAK      │ SINK 2: WASH      │ SINK 3: FINAL CRITICAL RINSE   │
├───────────────────┼───────────────────┼────────────────────────────────┤
│ Tepid water with  │ Submerged scrub-  │ Copious rinse with Critical    │
│ enzymatic solution│ bing with soft    │ Water (Deionized or Reverse    │
│ (80°F to 110°F)   │ nylon brushes     │ Osmosis) to remove all ions,   │
│ Loosens coagulum  │ under water line  │ minerals, and detergent films  │
└───────────────────┴───────────────────┴────────────────────────────────┘

Step-by-Step Manual Cleaning Workflow

1. Sink 1: Pre-Soak and Digestion:
   • Instruments are submerged in tepid tap water mixed with enzymatic detergent dosed precisely via calibrated metering dispensers according to the chemical manufacturer's IFU.
   • Water Temperature Critical Threshold: Water temperature must be maintained between 80°F and 110°F (27°C to 43°C). Water exceeding 140°F (60°C) coagulates and bakes albuminous proteins directly onto metal surfaces, rendering them impervious to detergents. Conversely, cold water below 70°F solidifies fats and inhibits enzymatic catalyst activity.
2. Sink 2: Manual Submerged Washing:
   • The Submersion Rule: Instruments must be brushed and manipulated entirely under the surface of the water. Scrubbing instruments above the water line or allowing running water to hit open bristles produces high-velocity infectious aerosols, spraying pathogens and detergent into the room atmosphere.
   • Brush Selection: Use only soft-bristle nylon brushes or designated polymeric lint-free cleaning cloths. Abrasive pads, wire brushes, and steel wool are strictly prohibited because they score and strip the passive chromium oxide finish, initiating rapid rusting.
   • Lumen Cleaning: Cannulas and suction tubes must be scrubbed using cylindrical nylon brushes matching the exact internal diameter and length specified in the device IFU. Brushes must be pushed completely through the lumen until the bristles exit the opposite end, pulled through, inspected, rinsed, and repeated until zero debris is detected.
   • Disassembly and Articulation: Open all box locks, ratchets, and scissor jaws to a 90-degree angle to scrub serrated teeth, crevices, and hinge pins.
3. Sink 3: Critical Water Rinsing:
   • After washing, instruments must be thoroughly rinsed with copious amounts of water to purge all loosened soil and chemical surfactant residues.
   • Critical Water Standard: The final rinse must utilize Critical Water—defined as water purified through Reverse Osmosis (RO), Deionization (DI), or Distillation.
   • Why Tap Water Fails for Final Rinse: Municipal utility tap water contains dissolved calcium, magnesium, silica, chlorides, and bacterial endotoxins (pyrogens). Mineral deposits dry into white chalky spotting, bind to steam sterilizer chambers, and inhibit steam contact. Endotoxins adhering to surgical instruments (especially intraocular instruments or orthopedic implants) induce severe post-surgical aseptic inflammation, such as Toxic Anterior Segment Syndrome (TASS) in cataract surgery.

Automated Cleaning Modalities: Ultrasonic Cavitation & Washer-Disinfectors

Following manual pre-cleaning and lumen brushing, surgical instruments undergo automated processing in specialized mechanical decontamination units.

1. Ultrasonic Cleaners (Acoustic Cavitation)

Ultrasonic cleaning is an automated physical-chemical cleaning process utilized primarily for complex, hinged, serrated, and micro-grooved instruments that cannot be thoroughly cleared by manual scrubbing alone.

• Mechanism of Action (Cavitation): The ultrasonic generator converts electrical energy into high-frequency sound waves (typically 20 kHz to 40 kHz), which propagate through the cleaning bath. These ultrasonic waves create alternating high-pressure and low-pressure acoustic cycles. In low-pressure phases, millions of microscopic sub-atmospheric vapor cavities (bubbles) form. During subsequent high-pressure phases, these cavitation bubbles violently implode, producing micro-jets of localized hydrodynamic energy reaching pressures of thousands of pounds per square inch and temperatures of thousands of degrees on a microscopic scale. This micro-scrubbing action tears debris away from box locks, serrations, and recesses without damaging fine metal edges.
• The Mandatory Degassing Protocol: Every time an ultrasonic tank is filled with fresh water and detergent, it must undergo a degassing cycle (typically run empty for 5 to 10 minutes according to the manufacturer IFU) prior to processing instruments. Tap water contains large quantities of dissolved air and carbon dioxide. If not degassed, ultrasonic energy dissipates into liberating dissolved air bubbles rather than generating effective cavitation, crippling cleaning efficiency.
• Metal Separation: Dissimilar metals (e.g., stainless steel, aluminum, brass, copper) must never be mixed in the same ultrasonic basket. Sound waves in an electrolytic detergent solution trigger galvanic corrosion, causing ion migration that electrochemically pits stainless steel and plates it with dark, irreversible copper or aluminum deposits.

2. Washer-Decontaminators & Washer-Disinfectors

Washer-disinfectors represent the cornerstone of automated ASC processing, executing programmed, multi-stage robotic cleaning, thermal disinfection, and drying cycles:

1. Pre-Wash Phase: Cool water rinse (under 110°F / 43°C) to flush away loose blood and tissue without coagulating proteins.
2. Enzymatic / Alkaline Wash Phase: High-pressure spray arms blast heated water (120°F to 140°F / 49°C to 60°C) mixed with enzymatic or neutral/mildly alkaline detergents to dissolve and saponify fats and proteins.
3. Neutralization / Intermediate Rinse Phase: Acidic neutralizing rinses counteract alkaline detergent residues, preventing scale formation.
4. Thermal Disinfection Phase: Heated water rinse where instruments are subjected to temperatures between 180°F and 194°F (82°C to 90°C) for a validated dwell time of 1 to 5 minutes (achieving an $A_0$ thermal lethality benchmark). This phase destroys vegetative bacteria and viruses, rendering instruments safe for personnel to handle with bare hands in the clean prep-and-packaging assembly room.
5. HEPA-Filtered Drying Phase: High-velocity forced air purges residual moisture, ensuring instruments emerge completely dry.