2.1 Sterile Technique and Asepsis

Surgical site infections (SSIs) represent a significant portion of healthcare-associated infections. As a Certified Surgical First Assistant (CSFA), your role is pivotal in establishing and maintaining the sterile field. This section covers the fundamental principles of sterile technique, environmental controls, and appropriate movement within the operating room.

Core Principles of Asepsis

Asepsis is the absence of pathogenic microorganisms. In the operating room, we strive for a surgical environment that minimizes the patient's exposure to potential pathogens. Strict adherence to aseptic technique is the foundation of infection prevention.

Sterility vs. Asepsis

While "sterility" refers to the absolute destruction of all living microorganisms (including spores), "asepsis" refers to the practices that restrict microorganisms in the environment and prevent contamination of the surgical wound. Because human skin cannot be sterilized, true absolute sterility of the entire OR is impossible; therefore, aseptic technique creates a defined "sterile field" within the room.

Establishing the Sterile Field

1. Timing: The sterile field should be created as close as possible to the time of use. Covering sterile setups is generally discouraged because removing the cover can create air currents that draw contaminants into the field.
2. Monitoring: Once established, a sterile field must never be left unattended. An unmonitored field is considered contaminated.
3. Edges are Unsterile: The edges of any sterile wrapper or drape are considered unsterile. A 1-inch margin around the perimeter of a sterile wrapper is standard practice for the unsterile boundary.

Environmental Controls

The operating room is a highly engineered environment designed to minimize airborne contamination.

Air Pressure and Filtration

Operating rooms are maintained under positive pressure relative to adjacent corridors. This means air flows out of the OR when doors are opened, preventing contaminated air from entering. The air is filtered using High-Efficiency Particulate Air (HEPA) filters, which remove particles as small as 0.3 microns with 99.97% efficiency.

Air Exchanges

Regulatory standards (AIA/FGI Guidelines and ASHRAE Standard 170) require a minimum of 20 total air exchanges per hour, with at least 4 of those being fresh outside air. Some specialized orthopedic or transplant rooms utilize laminar air flow, which provides up to 600 air exchanges per hour in a unidirectional flow to sweep particles away from the surgical site.

Temperature and Humidity

To inhibit bacterial growth and reduce static electricity risks, the OR environment is strictly controlled:

• Temperature: Typically maintained between 68°F and 73°F (20°C - 23°C).
• Humidity: Kept between 20% and 60%. High humidity increases condensation and moisture-related contamination, while low humidity increases the risk of electrostatic discharge, which is a fire hazard.

Movement in the Operating Room

Movement within the OR must be deliberate and purposeful to prevent accidental contamination.

Defining the Sterile Areas of a Gown

Even after a surgical team member is scrubbed and gowned, not the entire gown is considered sterile. The sterile areas are strictly defined as:

• The front of the gown from the chest down to the level of the sterile field.
• The sleeves from two inches above the elbow down to the cuff.

The neckline, shoulders, underarms, back, and areas below the level of the sterile field are all considered unsterile. The cuff of the gown is considered unsterile once the hands pass through it, which is why sterile gloves must completely cover the cuffs.

Rules for Movement

1. Sterile to Sterile: Sterile personnel touch only sterile items or areas; unsterile personnel touch only unsterile items or areas.
2. Passing Protocol: When sterile team members must change positions, they should pass each other either face-to-face or back-to-back. A sterile person should never turn their back to the sterile field.
3. Distance from Field: Unsterile personnel (such as the circulator) must maintain a minimum distance of 12 to 18 inches from any sterile area.
4. Draping: When applying drapes, they should be placed on the patient and not moved. Shifting a drape can bring contaminants from an unsterile area (like the skin) up into the sterile field.

Compromises in the Sterile Field

Any break in sterile technique must be addressed immediately.

• Strike-through contamination: This occurs when moisture permeates a sterile barrier, drawing contaminants through from an unsterile surface below. If a drape becomes wet, it must be covered with an impermeable sterile towel or completely replaced.
• Doubt means Contaminated: The golden rule of surgical technology and assisting: "If in doubt, throw it out." If there is any question about the sterility of an item, it must be considered unsterile.