Aseptic Practices: Preparing the Sterile Field and Staff for Surgery

Surgical Site Infections and Infection Control Principles

• A surgical site infection (SSI) is a healthcare-associated infection (HAI) occurring in the part of the body where a surgical procedure was performed. SSIs can involve skin, deep subcutaneous tissue, organs, or implanted foreign materials (such as a total hip replacement).

• According to Centers for Disease Control and Prevention (CDC) HAI prevalence surveys, an estimated $110{,}800$ SSIs were associated with inpatient surgeries in 2015.

• Data published in the 2022 National Healthcare Safety Network (NHSN) HAI Progress Report demonstrated approximately a $4\%$ increase in the SSI standardized infection ratio (SIR) across all NHSN operative procedure categories combined relative to the previous year.

• SSIs represent $20\%$ of all HAIs in hospitalized patients and are associated with a 2-to-11-fold increase in mortality risk. Approximately $75\%$ of deaths among patients with an SSI are directly attributable to the infection itself.

• Interventions can successfully reduce infection incidence; for example, a study by Bediako-Bowan et al. (2020) conducted in Ghana demonstrated a decrease in SSI incidence risk from $12.8\%$ to $7.5\%$

• Microorganisms commonly isolated from SSIs include:

  • Staphylococcus aureus

  • Staphylococcus epidermidis

  • Coagulase-negative staphylococci

  • Enterococcus species

• An increasing proportion of SSIs are caused by antimicrobial-resistant pathogens, rendering treatment difficult or impossible.

• Pathogen Virulence and Inoculum Size:

  • Virulence defines the physical or biochemical capacity of a microorganism to cause disease. Highly virulent strains or pathogens containing endotoxins require a smaller inoculum size to establish an infection compared to less virulent organisms.

  • Endotoxins are lipopolysaccharide components located within the outer cell wall of gram-negative bacteria (such as Escherichia coli and Pseudomonas species) that are released upon bacterial cell lysis.

• Endogenous vs. Exogenous Sources of Infection:

  • Endogenous infection sources originate directly from the patient's own native microbial flora residing on skin surfaces, mucous membranes, or within hollow viscera. Most SSIs stem from endogenous flora that are displaced during surgical entry.

  • The skin serves as the primary physical barrier against microbial entry. Incising intact skin creates a portal of entry for opportunistic pathogens.

  • Exogenous sources arise from external environmental contamination or healthcare personnel present in the operating suite.

• Patient-Specific Infection Risk Factors:

  • Prolonged exposure of internal tissue (extended surgical duration).

  • Presence of artificial implants or metallic hardware.

  • Volume of ischemic or devitalized tissue present within the wound bed.

  • Extremes of age: Geriatric patients experience impaired tissue healing secondary to reduced vascular perfusion (e.g., atherosclerosis) or coexisting chronic systemic conditions. Neonatal patients—particularly premature infants—possess diminished globulin synthesis, immature antibody formation, impaired cellular defense mechanisms, and lower body mass, making them highly susceptible.

  • Nutritional impairment: Malnutrition associated with chronic disease, substance abuse, or alcoholism delays tissue repair.

  • Obesity: Adipose tissue exhibits poor vascularity; avascular tissue is inherently vulnerable to bacterial colonization and ischemia.

  • Immunosuppression: Systemic administration of corticosteroids, chemotherapy agents, immune-suppressive medications, radiation therapy, or underlying acquired immune deficiency syndrome (AIDS) impairs primary host defense mechanisms.

  • Chronic systemic diseases: Diabetes mellitus, malignancy, cardiovascular disease, and chronic respiratory disorders impose metabolic stress that compromises immune responses.

  • Preexisting remote infections: Active infection anywhere in the body significantly elevates SSI risk and serves as an absolute contraindication for elective surgical procedures.

  • Burn injuries or severe skin breakdown: Destruction of epithelial integrity removes primary mechanical resistance to pathogen entry.

  • Presence of invasive lines, catheters, and drains: Drains and catheters provide direct physical conduits for bacterial migration into deep anatomical spaces; risk scales directly with duration of placement.

  • Nicotine use and tobacco smoking: Nicotine induces cutaneous vasoconstriction and decreases tissue oxygen delivery, impairing wound healing.

• Healthcare Personnel as Exogenous Vectors:

  • Personnel are the primary dynamic source of airborne microorganisms in the operating room. Microorganism counts scale directly with the density of personnel inside the room.

  • Colonized individuals host pathogenic microorganisms without demonstrating active clinical infection, serving as asymptomatic transmission reservoirs.

  • High shedding anatomical regions include the scalp, neck, axillae, hands, groin, legs, and feet.

  • Hair harbors high concentrations of Staphylococcus species; contamination density correlates with hair length and cleanliness. All hair must be fully enclosed in surgical caps or hoods.

  • Respiratory activities—including talking, laughing, coughing, and breathing—expel micro-droplets containing viable flora.

Chipped nail polish contains microscopic fissures that harbor high bacterial loads. Facility policies require personnel to remove chipped polish or abstain from wearing polish entirely.

• Artificial nails harbor gram-negative pathogens both before and after hand hygiene; microbial counts increase with wear duration. Personnel with artificial nails frequently perform sub-optimal surgical hand scrubs to protect manicures.

• Rings, watches, and bracelets retain organic debris and harbor bacteria; all jewelry must be removed or fully covered by surgical attire.

Operating Room Architectural Layout and Environmental Controls

• Geographical Location:

  • Surgical suites are situated close to critical care units, central sterile supply departments (CSSD) or sterile processing departments (SPD), clinical pathology laboratories, and diagnostic radiology departments.

• Physical Traffic Zones:

  • Unrestricted Area: Street clothing is permitted. Includes peripheral corridors, patient reception areas, dressing rooms, offices, and the central control desk. Serves as the primary transition point between external hospital corridors and the restricted surgical environment.

  • Semi-Restricted Area: Restricted to authorized personnel wearing dedicated surgical scrub attire and complete hair/beard coverings. Includes peripheral support corridors, storage areas for clean and sterile supplies, instrument processing workrooms, and corridors leading directly to operating suites. Bald heads must be covered to prevent shedding of desquamated skin cells and dander.

  • Restricted Area: Full surgical attire, head coverings, and surgical face masks are mandatory wherever open sterile supplies or scrubbed personnel are present. Includes individual operating rooms, procedure rooms, sub-sterile utility spaces, and scrub sink areas. Non-surgical personnel entering briefly (e.g., laboratory technicians) must wear clean cover gowns or jumpsuits, caps, shoe covers, and masks.

  • Transition Zones: Designated entry areas equipped with lockers or supply carts containing cover garments, masks, caps, and shoe covers, allowing controlled movement between unrestricted and restricted zones.

• Ancillary Surgical Suite Units:

  • Preoperative Admission and Holding Unit: Located within the unrestricted area to shield patients and families from distressing clinical sights and sounds. Equipped with emergency crash carts, advanced airway devices, resuscitation medications, oxygen supplies, suction, and physiological monitors. Used for preoperative baseline vital sign assessment, medical record verification, checklist completion, IV placement, regional nerve blocks, and preoperative shave preparations.

  • Induction Room: Specialized room located in the restricted zone adjacent to the operating room for anesthesia induction and airway management prior to entering the main suite. Minimizes patient transfers by using the operating table itself as a transport gurney locked into a permanent floor base.

  • Postanesthesia Care Unit (PACU): Positioned adjacent to the surgical suite with dual access corridors (semi-restricted and unrestricted) to act as a secure exit transition zone for recovering patients. Features dedicated family waiting areas and private physician consultation rooms.

  • Central Control Desk: Situated within the unrestricted zone adjacent to semi-restricted access corridors. Staffed by a clerk-receptionist utilizing a glass pass-through window to manage communications, coordinate room schedules, and receive incoming medications, blood products, and supplies.

  • Anesthesia Work and Storage Space: Dedicated environment for storing anesthesia machines, monitoring supplies, and pharmaceutical agents (utilizing automated dispensing cabinets requiring positive user identification). Compressed gas cylinders must be secured upright in stable bases with full and empty tanks physically segregated. Requires negative pressure ventilation with at least $8$ air exchanges per hour.

• HVAC and Environmental Parameters:

  • Positive Pressure Plenum Ventilation: Operating rooms utilize positive pressure air supply system ($10\%$ positive pressure differential relative to adjacent corridors). Air flows outward from the operating room into peripheral corridors, preventing infiltration of unconditioned, contaminated air.

  • Air Movement and Circulation: Room doors must remain closed to maintain pressure differentials. External windows must not be opened. Continuous air changes flush out anesthetic vapors and airborne particulates.

  • Relative Humidity Control: Maintained precisely between $20\%$ and $60\%$. Relative humidity exceeding $70\%$ risks moisture condensation inside sterile wrapped packages, inducing strike-through contamination via capillary action. Relative humidity below $20\%$ permits static electricity buildup.

  • Ambient Temperature Range: Regulated between $68^\circ\text{F}$ and $75^\circ\text{F}$ ($20^\circ\text{C}$ to $24^\circ\text{C}$). Temperature is increased during pediatric, geriatric, or extensive burn procedures to prevent patient hypothermia.

• Architectural Features and Lighting:

  • Doors: Surface-sliding doors are required for main entrances to minimize turbulence and displacement of settled environmental dust. Swinging doors create significant air currents that elevate ambient bacterial counts, which peak during initial skin draping and incision.

  • Illumination: Combination of white fluorescent or incandescent overhead ceiling lights and ceiling-mounted mobile spotlight fixtures. Must provide shadowless light distribution without distorting tissue color. Anesthesia providers require clear illumination to evaluate patient skin tone and mucous membrane perfusion. Surgical drapes are colored blue, green, or neutral gray to mitigate ocular fatigue.

• Standard Operating Room Furniture:

  • Constructed of smooth, seamless stainless steel for ease of cleaning and disinfection.

  • Operating room bed featuring segmented articulation, foam/gel pressure-relieving pads, fluid-impervious cover, arm boards, and positioning attachments.

  • Instrument back tables (large rectangular surfaces positioned lateral to the scrubbed nurse).

  • Mayo stand: Height-adjustable cantilevered frame supporting a removable stainless steel tray positioned directly over the sterile field for immediate-use instruments.

  • Small auxiliary tables for gowning/gloving and skin prep supplies.

  • Ring stands to hold sterile fluid basins (if splash basins are used).

  • Sitting stools, stackable standing platforms, mobile dual-canister suction machines, laundry frames, kick buckets (sponge buckets on rolling bases), wall desks, and computer stations (oriented so the circulating nurse maintains line-of-sight visual monitoring of the sterile field).

Standard, Transmission-Based, and Occupational Safety Precautions

• Evolution of Infection Control Guidelines:

  • Universal Precautions were established by the CDC in 1987 to prevent bloodborne transmission of human immunodeficiency virus (HIV), hepatitis B virus (HBV), and other bloodborne pathogens.

  • Standard and Transmission-Based Precautions were instituted in 1996, expanding protections across all healthcare settings.

  • Occupational Safety and Health Administration (OSHA) Bloodborne Pathogens Standard (1992) mandated actionable workplace compliance protocols.

• OSHA Mandatory Universal Precaution Provisions:

  • Requirement for employers to identify and list job classifications with potential occupational blood/body fluid exposure.

  • Mandatory provision of personal protective equipment (PPE) at zero cost to employees.

  • Gloves must be worn when direct contact with blood, body fluids, or contaminated surfaces is anticipated.

  • Masks combined with full-face shields or protective glasses with solid side shields must be worn during procedures generating blood or fluid splashes, spray, or aerosols.

  • Fluid-resistant or fluid-proof gowns must be worn when fluid splattering is anticipated; gowns must completely prevent fluid strike-through.

  • Skin and hand surfaces must be washed immediately following contact with blood or body fluids.

  • Contaminated needles must not be recapped, bent, or removed by hand. If recapping is required by a specific medical protocol, a mechanical safety device or a one-handed scoop technique must be utilized.

  • Needles, scalpels, and sharps must be disposed of in rigid, puncture-resistant, leak-proof containers located immediately at the point of use.

  • Formal schedules for environmental surface cleaning and chemical disinfection must be maintained.

  • Soiled linen and contaminated waste must be isolated in labeled or color-coded leak-proof bags or containers.

• Standard Precautions Application:

  • Applies to blood, all body fluids, secretions, and excretions (excluding sweat), regardless of the presence of visible blood or suspected infection status.

  • Mandates PPE selection tailored to exposure potential and immediate hand hygiene.

• Transmission-Based Isolation Categories:

  • Airborne Precautions: Used for pathogens $$≤ 5\,̦̦̀̀