Principles of Surgical Asepsis Study Notes

Principles of Surgical Asepsis

Asepsis vs. Antisepsis

• Asepsis: The practice and process designed to prevent or minimize wound contamination by destroying or excluding pathogenic microorganisms from the surgical field before they enter a wound. This aims to create a completely microbe-free environment for invasive procedures.

• Antisepsis: The act of killing or inhibiting the growth of bacteria and other microorganisms after they have entered a wound or are present on living tissue. It is crucial in managing existing contamination or preventing its spread on biological surfaces.

• Antiseptics: Chemical agents and formulations specifically approved for use on living tissue (skin, mucous membranes) to reduce the number of microorganisms, typically before an invasive procedure or to treat contaminated wounds. They generally have a lower toxicity profile than disinfectants.

Disinfection & Sterilization

• Disinfectants: Chemical agents and formulations approved exclusively for use on inanimate objects and surfaces to kill most microorganisms. They are generally too harsh for living tissue.

• Key Differences: While antiseptics and disinfectants may share the same primary active chemical agents (e.g., alcohols, iodophors, chlorhexidine), they differ significantly in their concentrations, specific additives, and diluents, which are carefully selected to be appropriate for their respective applications (living tissue vs. inanimate objects).

• Disinfection: The use of physical or chemical germicidal substances (disinfectants) to kill most vegetative microorganisms, including many bacteria, fungi, and viruses, but not necessarily bacterial spores. This process reduces the microbial load on surfaces to a safe level.

• Sterilization: The most rigorous process that destroys all forms of microbial life, including highly resistant bacterial spores, fungi, and viruses. It is an absolute process essential for critical items that directly contact the bloodstream or sterile tissues within the body.

Chemical Agents and Their Concentrations

Aseptic Surgical Technique

• Goal: The overarching purpose is to meticulously minimize the introduction of pathogenic microorganisms into surgical wounds and subsequently reduce the risk of surgical site infections (SSIs).

• Most surgical wounds contain some bacteria by the end of the procedure due to the omnipresence of microorganisms and the invasive nature of surgery; the goal is to keep this count below the threshold for infection.

• The diligent application of aseptic technique is paramount for establishing and maintaining an environment that significantly minimizes infection risk, thereby ensuring patient safety and promoting optimal healing.

• Protocols often display variations between institutions and practitioners due to the historical lack of strong, large-scale evidence from controlled, randomized studies. Many practices are based on tradition or small-scale observations.

• Ethical Issues: Standard Operating Procedures (SOPs) are frequently developed based on expert opinion, consensus guidelines, or smaller, less robust studies, prompting ongoing re-evaluation and research efforts to establish evidence-based best practices.

Surgical Team Preparation

• Personal Hygiene:

  • No rings, watches, bracelets, or necklaces should be worn in the operating room as they harbor microorganisms and impede effective hand scrubbing.

  • Earrings, if worn, must be entirely covered by a surgical cap to prevent shedding of hair or skin cells.

  • Fingernails must be trimmed to 2mm or less beyond the soft tissue pad of the finger to prevent glove punctures and reduce subungual microbial load.

  • Artificial eyelashes or nails are strictly prohibited, and nail polish (especially chipped) should be avoided as it can harbor bacteria and compromise sterility.

Surgical Attire

• Lab Coat:

  • Worn over surgical scrubs outside the operating room to provide a barrier, protecting scrubs from environmental hair and loose debris. It acts as an outer layer that should be shed before entering sterile areas.

  • Must be removed immediately upon entering the designated sterile preparation or operating room area to prevent the transfer of external contaminants.

• Surgical Scrubs:

  • Tops must be tucked into the scrub pants to prevent exposure of bare skin and reduce the 'piston effect' of air movement under the garment, which can propel skin cells into the environment.

  • Sleeves should ideally be above the elbow (minimum 4 inches above the elbow) to allow for effective surgical hand scrubbing of the forearms.

  • T-shirts worn underneath scrubs should not peek above the neck of the gown or extend below the sleeve of the scrubs, as they are typically non-sterile and can introduce contamination.

  • Scrubs must be laundered frequently, ideally after each use, in a healthcare-approved facility using specific protocols to ensure microbial reduction.

• Footwear/Shoe Covers:

  • Best practice involves having shoes specifically designated for surgery only, which are washable and regularly cleaned to prevent tracking of pathogens from outside the OR.

  • Shoe covers are often used to contain debris from street shoes and should be removed before leaving the restricted area.

Aseptic Surgical Hand Preparation

• Hand Hygiene:

  • Begin with a general hand and arm wash using soap and water to physically remove gross dirt, debris, and transient microorganisms before the surgical scrub.

  • The surgical scrub procedure is designed not only to reduce the surface bacterial count immediately but also to suppress the regrowth of microorganisms for a minimum of 6 hours, ensuring sustained low bacterial levels throughout the surgical procedure.

• Scrubbing Agents:

  • Water-based scrubs (e.g., Chlorhexidine gluconate (CHG), Povidone iodine) are traditionally used and involve a wet scrubbing process, detailed in further sections.

  • Alcohol-based scrubs: Highly effective, typically containing 61% alcohol combined with 1% Chlorhexidine gluconate (CHX) are common in human and increasingly in veterinary surgery. These provide rapid bacterial kill. A pre-wash with non-antimicrobial soap and water is required to remove gross contamination before applying the alcohol-based solution.

Water-based Scrubs

• Chlorhexidine (CHX) Gluconate: A biguanide antiseptic known for its broad spectrum of activity and prolonged effect.

  • Achieves 70%-80% bacterial reduction on initial application and up to 99% reduction with repeated applications. Its effectiveness is due to its binding to the skin (substantivity).

  • Requires a contact time of 3-5 minutes (a 5 minute scrub is common in many protocols) for optimal efficacy, allowing the agent to penetrate and act on microorganisms.

  • Its effectiveness lasts for at least 6 hours due to its residual activity, but it may cause skin irritation in some individuals, especially with frequent use.

• Povidone Iodine (PVI): An iodophor antiseptic that releases free iodine, a potent microbicide.

  • Provides a 70%-80% bacterial reduction, but offers less residual activity compared to CHX, leading to more rapid microbial regrowth after scrubbing. It has a faster drying time when in alcoholic solutions.

  • Skin irritation and damage are more common with povidone-iodine, particularly with the extensive range of concentrations typically used (7.5%-10% solutions/scrubs), and in individuals with iodine sensitivity.

• Water Consumption: Water-based scrubs typically consume a significant amount of water, often around 20L per scrub, which has environmental implications and has led to the development of waterless hand rub alternatives.

Water-based Scrub Technique

• Scrubbing Process: A systematic and meticulous process to ensure all surfaces of the hands and forearms are adequately exposed to the antiseptic.

  • Use the bristle side of the scrub brush only on nail tips to effectively clean subungual areas and prevent damage to skin; the foam side or soft sponge side is appropriate and gentler for the skin surfaces of hands and arms.

  • Apply the chosen scrub solution to hands and arms up to the elbows, ensuring comprehensive coverage while carefully avoiding contact with non-sterile attire or surroundings, especially sleeves.

  • Allow adequate contact time, vigorously scrubbing all surfaces (fingers, palms, backs of hands, forearms) for the prescribed duration; rinse thoroughly, always allowing water to run from fingertips to elbows to prevent re-contaminating scrubbed areas.

  • If any non-sterile objects (e.g., faucet, unsterile gown part) are inadvertently touched after the scrub, a complete re-scrub from the beginning is necessary to maintain aseptic integrity.

Surgical Gowns and Patient Drapes

• Materials: The choice of material is crucial for barrier efficacy.

  • Reusable tightly woven cotton muslin cloths (typically 240-270 threads/inch) were historically used. They offer some barrier protection but are prone to becoming saturated and allowing moisture (and thus bacteria) to 'strike through' when wet.

  • Disposable non-woven materials, often made from synthetic polymers, provide excellent barrier protection due to their intricate fiber structure. However, their barrier efficacy can be compromised (fabric pores can widen) with excessive manipulation or stretching.

  • Gowns and drapes must be made of materials impervious to bacteria and water. This impermeability is critical to prevent bacterial strike-through, where fluid penetration allows microorganisms to pass from non-sterile to sterile areas.

Gowning Procedure

• Method:

  • Gowning should ideally occur in a sterile corridor or designated area where the risk of contamination is minimized. The sterile person must keep their hands and arms within their view and between waist and shoulder level (the 'sterile field') at all times to avoid accidental contamination.

  • Sterile Back Technique: This highly controlled method involves assistance from a scrubbed or trained circulating team member to tie and secure the gown properly without compromising the sterile field. The back of the gown is considered non-sterile once donned.

• Closed Gloving Technique: This is the preferred method for donning sterile gloves after gowning, as it minimizes the risk of the bare hand touching the outside of the sterile glove. It involves pulling the glove over the gown cuff without exposing skin. This technique is considered safer compared to open gloving techniques where bare hands directly contact the glove's cuff.

  • Gloves should be meticulously inspected for holes or tears before and during use, as studies indicate a significant rate of compromised glove integrity (contamination rates) over even short surgical procedures, increasing the risk of infection.

Surgical Waiting and Prep Protocols

• Pre-anesthesia Preparation: Scrubbed personnel, while waiting for the patient to be anesthetized and prepped, must maintain their hands at chest level, clasped, and away from their body. They must avoid contact with non-sterile surfaces, including their own axillae or face.

• Sterile Drape Application: Extreme care must be taken during the application of sterile drapes to minimize the risk of contamination. This involves careful unfolding, precise positioning, and avoiding any contact with non-sterile areas (e.g., patient's non-prepped skin, operating table edges) or allowing drapes to fall below table level. When applying quarter drapes, each drape's sterile surface should only contact other sterile surfaces or the prepped surgical site.

Important Comparisons for Antiseptic Solutions

• Povidone-Iodine: Typically used in aqueous solutions, it releases 1% free iodine concentration. While gentler on the skin, its water-based formulation leads to longer drying times. Prolonged wetness can macerate the skin and potentially lead to irritation.

• Tincture of Iodine: Contains a higher free iodine concentration due to its alcohol-based formulation. This allows for faster drying but can irritate the skin more quickly and severely, particularly in sensitive individuals or with repeated applications.

Instrument Processing Steps

1. Cleaning: Immediate cleaning after surgery is paramount. Organic material (blood, tissue, debris) can dry onto instruments, forming a biofilm that protects microorganisms and can lead to corrosion. Manual or automated cleaning (e.g., ultrasonic cleaners) removes this bioburden.

2. Inspection: After cleaning, all instruments must be thoroughly checked for correct function (e.g., proper alignment of jaws, sharpness of edges, integrity of insulation on electrocautery tools). Instruments are also lubricated (e.g., with water-soluble instrument milk) to prevent rust and maintain articulation, then organized into sets for sterilization.

Sterilization Methods

• Autoclaving: The most common and reliable method. Saturated steam sterilization is highly effective for heat-tolerant and moisture-tolerant materials. Operates at specific temperatures and pressures (e.g., 121°C (250°F) at 15psi for 15 minutes, or 132°C (270°F) at 27psi for 4 minutes).

  • Limitations: Pack size must be controlled (e.g., no thicker than 12 inches) to ensure proper steam penetration and efficient sterilization of all contents.

• Chemical Sterilization using Ethylene Oxide (EtO): An effective method for heat-sensitive and moisture-sensitive materials. It works by alkylation of microbial proteins. However, it involves a longer timeframe for processing, including extended aeration periods (up to 12-18 hours) to remove toxic gas residues.

• Gas Plasma Sterilization: Utilizes hydrogen peroxide gas plasma (e.g., by STERRAD systems) to sterilize heat- and moisture-sensitive instruments. It is safer and quicker than Ethylene Oxide, produces no harmful residues, and requires no aeration. However, it has high initial equipment costs and limitations on lumen size and material compatibility.

Sterilization Monitoring and Quality Control

• Biological Indicators (BIs): These are the only direct measure of sterilization effectiveness. Tests systems typically use resistant bacterial spores (e.g., Geobacillus stearothermophilus for steam and hydrogen peroxide plasma sterilization; Bacillus atrophaeus for EtO) that are exposed to the sterilant and then cultured. If spores are killed, the sterilizer is considered effective. Surveillance strips (Class VI chemical indicators) provide real-time assurance that all sterilization parameters have been met.

• Luminometer Principle: Measures adenosine triphosphate (ATP) levels on surfaces to assess cleanliness. ATP is present in all living organic matter. The luminometer reports results in Relative Light Units (RLU), where higher RLU values indicate greater contamination (more organic residue present), helping monitor cleaning efficacy before sterilization.

Historical Context

• Joseph Lister: Recognized as the pioneer in antiseptic medicine in the mid-19th century. He established principles to prevent bacteria from entering surgical wounds (using carbolic acid), fundamentally impacting modern surgical practices and significantly reducing post-operative infection rates.

Summary of Key Concepts

• Breaks in Aseptic Technique vs. Break in Asepsis: Understanding distinctions is vital for maintaining procedural integrity and minimizing risks. A 'break in aseptic technique' refers to an observable event that compromises the sterile field (e.g., gloved hand touches unsterile surface). A 'break in asepsis' refers to the actual contamination of the sterile field, often as a result of a break in technique, but can also occur via unseen means.

• Sterile Pack Shelf Life: Sterile packs should be carefully marked with the date of sterilization and an expiration date (if applicable). They require meticulous inspection for any damage (e.g., tears, moisture, punctures) to the packaging before use, as compromised packaging renders the contents non-sterile.

Contact Information

• Ross University School of Veterinary Medicine: Contact details for further inquiries were provided.

• "In the realm of surgery, asepsis is not just a practice but a pledge to protect every life we touch."