Preparing a patient’s skin before a surgical incision is known as surgical antisepsis. This procedure involves using specialized chemical agents to cleanse the area where the surgeon plans to cut. The fundamental goal is to drastically reduce the population of microorganisms present on the skin surface. Lowering the bacterial count minimizes the risk of these microbes contaminating the wound once the skin barrier is opened.
The Necessity of Surgical Site Preparation
The patient’s skin naturally harbors a diverse community of bacteria, known as resident flora, even when visibly clean. An incision provides a direct pathway for these microorganisms to enter deeper tissues, which can lead to a Surgical Site Infection (SSI). Preventing SSIs is the central purpose of preoperative skin preparation, as these infections are a major complication of surgery.
The patient’s own bacterial flora is the main source of pathogens for most SSIs. When microbes are introduced into the wound, they can cause complications that increase a patient’s length of hospital stay and healthcare costs. Applying an antiseptic agent dramatically reduces the microbial burden, helping to mitigate the risk of patient morbidity.
Common Antiseptic Agents Used
The most frequently used chemical agents for surgical skin preparation fall into two primary categories: Povidone-iodine (PVI) and Chlorhexidine Gluconate (CHG). Povidone-iodine is an iodophor compound that works by rapidly penetrating the microbial cell wall, where it oxidizes proteins and lipids, causing cellular death. PVI offers a wide spectrum of antimicrobial activity, but its effect is relatively short-lived once applied to the skin.
Chlorhexidine Gluconate is a cationic biguanide that disrupts the bacterial cell membrane, causing the leakage of intracellular contents. A benefit of CHG is its persistent activity, meaning it continues to kill microorganisms for an extended period after application. CHG also resists inactivation by organic materials like blood or tissue fluid, which may be present during a procedure.
The third component often integrated with these agents is alcohol, typically isopropyl or ethyl alcohol. Alcohol is a fast-acting, broad-spectrum antiseptic that rapidly denatures proteins in the microbial cell. When combined with CHG or PVI, the alcohol provides a quick initial kill, while the other agent offers a sustained residual effect.
Alcohol-based solutions are preferred due to their enhanced and rapid efficacy, unless there is a specific contraindication. Aqueous-based solutions are necessary for procedures involving mucous membranes, the eyes, or the inner ear, where alcohol or CHG can cause irritation or toxicity. The choice of agent is also guided by the surgical site and any known patient allergies.
Proper Application Technique and Timing
The method for applying the antiseptic solution is a standardized procedure designed to maximize microbial reduction and maintain a sterile field. The agent is applied starting at the planned incision site, which is considered the cleanest area, and then moves outward toward the periphery in a smooth, continuous motion. The applicator is never brought back toward the center of the prepped area once it has touched the surrounding skin.
Adequate contact time is required for the solution to achieve its full antimicrobial effect, with the specific duration dictated by the manufacturer. Most manufacturers recommend a minimum of two to three minutes of application and drying time for alcohol-based solutions. Allowing the solution to completely air dry is the most important procedural step before the surgical drapes are placed or the incision is made.
Complete air drying is a fundamental safety measure, especially when using flammable alcohol-based products. If the solution is not fully dry, alcohol vapor can accumulate under the sterile drapes and ignite when electrosurgery is used, creating a fire hazard. To prevent pooling of excess liquid, sterile towels are used to absorb any drips before the solution settles under the patient, and then sterile surgical drapes are positioned.