Aseptic Technique - Clinical Tree

Chapter Summary

In surgical procedures, there are four potential sources of contamination: the personnel, the surgical environment, the patient, and the instruments, with the patient's normal flora being the most common reservoir.
Appropriate measures to ensure aseptic technique depend upon the procedure, the anatomical site of the surgical procedure, and the degree of contamination within the wound. There are basic precautions that should be adhered to, including:
- Hand antisepsis before donning surgical gloves and after their removal
- Caution with the application of alcohol-containing preparations because they are extremely flammable and should be allowed to dry completely before laser or electrocautery are used
- Surgical antiseptic agents are safe and effective for preoperative skin preparation in almost all situations with the following caveats:
  - chlorhexidine gluconate is an irritant and should not be allowed to make contact with the eye or middle ear because permanent damage may occur
  - povidone-iodine must remain in contact with the skin to maintain its disinfective qualities
- Hair removal is only indicated if the hair will obscure the surgical field or hinder proper surgical technique.

Introduction

When it had been shown by the research of Pasteur that the septic property of the atmosphere depended not on the oxygen or any gaseous constituent but on minute organisms suspended in it … it occurred to me that decomposition in the injured part might be avoided … by applying some materials capable of destroying the life of the floating particles. The material which I have employed is carbolic … acid (Lister J. On the antiseptic principle in the practice of surgery. Lancet 1867; 2:353–356.)

Before 1860, most surgery was performed reluctantly and with the understanding that the operation was as likely to kill the patient as the disease. Regardless of the success of the operation, the vast majority of patients died within a few days from overwhelming sepsis. Although less than 150 years ago, this was a time when the prowess of a surgeon was evidenced by the amount of blood encrusted on his coat. If a scalpel became dull during an operation it was promptly sharpened on the sole of an assistant's shoe and then placed back into the wound. Lint and sawdust from the floor were used as hemostatics, surgical sponges were reused without laundering, and it was believed wound infections were generated spontaneously by exposure to air.

The modern era of surgery began in the mid-nineteenth century, with the development of anesthesia. Once the pain from surgery was conquered, surgeons were free to focus on technique rather than speed. Despite their best efforts, hospital gangrene and death remained dreaded, but frequent, outcomes of most major operations. This dismal mortality rate remained unchanged until Pasteur introduced the germ theory of disease, which would later form the basis of Joseph Lister's principles of surgical antisepsis.

In 1867, Lister deduced that “… the essential cause of suppuration in wounds is decomposition, brought about by the influence of the atmosphere.” His antiseptic surgical technique consisted of washing the surgeon's hands, instruments, operating room environment, and surgical site with carbolic acid (phenol). He also devised an atomizer, which produced a continuous mist of carbolic acid into the air during surgery. Lister published an article in 1870, which described the influence of these measures on the deplorable conditions of the surgical wards at the Glasgow Royal Infirmary, the stench of which was notorious. After 9 months of strict adherence to handwashing and carbolic acid antisepsis, there was not a single case of hospital gangrene, pyemia, or erysipelas in the entire ward. Unfortunately, these dramatic findings were met with strong opposition from the medical community and it took almost 10 years before surgeons began to adopt his recommendations.

“Listerism,” or antisepsis, markedly decreased the mortality from surgery, but the atmosphere of the surgical suite was laden with carbolic acid, which was toxic to surgeons and other personnel who were chronically exposed to its vapors. In addition, carbolic acid was caustic when applied directly to open wounds. This prompted the search for alternative antiseptics with less morbidity, such as iodine and alcohol. The next step in surgical antisepsis was the sterilization of instruments and bandages, which became possible in 1886, when von Bergmann developed a superheated steam system similar to the modern autoclave. Sterilization of the surgeon's hands remained a challenge until Halsted introduced “boilable” rubber gloves in 1890. Mikulicz added further refinement to the aseptic technique when he described the benefits of wearing a gauze mask in 1897, and MacDonald recognized the infection risk posed by “theatre spectators” gathered around the operating table.

Over the last 100 years, aseptic technique has evolved into a set of well-defined practices designed to reduce the risk for surgical site infection (SSI). Dermatologic surgeons perform a broad range of procedures in a variety of settings. Appropriate measures to ensure aseptic technique depend upon the invasiveness of the proposed procedure and the risk for infection. These measures range from the use of non-sterile gloves and an alcohol skin-wipe for shave biopsies, to full surgical dress and strict asepsis for liposuction. This chapter outlines the major components of the aseptic technique and their applicability to dermatologic surgery.

Normal flora

The human body is colonized with microorganisms that are collectively known as indigenous or normal flora. The density and composition of these microorganisms vary with different anatomic locations on the body, and on the skin are largely determined by local humidity and lipid content. Skin flora can be divided into two distinct populations: resident flora and transient flora.

Resident flora

Resident flora have stable population densities and can be isolated in similar numbers from most individuals. These symbiotic microorganisms help protect the host from infection by competing with pathogens for substrate and tissue receptors. Resident flora inhabit the surface of the skin, as well as deeper structures, such as the pilosebaceous unit. Deeply embedded organisms are resistant to mechanical removal and are beyond the reach of topical antiseptic solutions. Given this inherent limitation, the goal of preoperative skin cleansing is to decrease resident flora to its lowest possible level, with the realization that it cannot be completely eradicated.

The most common resident organisms are the coagulase-negative staphylococci, with Staphylococcus epidermidis accounting for more than 90% of resident aerobes. Anaerobic diphtheroids such as Propionibacterium acnes are common in lipid-rich locations, such as the pilosebaceous unit. Gram-negative bacteria represent a small portion of the resident flora. They are mostly limited to the humid intertriginous areas with Enterobacter , Klebsiella , Escherichia coli , and Proteus spp. being the predominant organisms.

Transient flora

Transient flora are acquired through contact with people, objects, or the environment. They are loosely attached to the surface of the skin and are amenable to removal by washing. The majority of postoperative wound infections are due to transient microorganisms that contaminate the wound during surgery. In most cases, the source is the endogenous flora of the patient's nose, throat, or skin. Exogenous sources of contaminating flora include the surgical personnel, the local environment (including air), surgical instruments, and materials brought into the sterile field during surgery. Based on the Centers for Disease Control and Prevention (CDC) data examining all types of SSIs, Staphylococcus aureus ( S. aureus ) is the most frequent organism isolated, followed by coagulase-negative staphylococci, Enterococcus spp., E. coli , group A streptococci and Pseudomonas aeruginosa .

Most pathogens are transmitted via one of four basic routes: contact, air-borne, vehicle, or vector. For surgical procedures, the contact and air-borne routes are the most likely means of contamination. Contact transmission may be indirect where organisms are transferred via fomites (e.g., if a suture touches contaminated skin and is then placed into the wound) or direct (if contaminated skin of the patient or surgeon touches the wound). During air-borne transmission, microorganisms are not suspended freely but carried on desquamated skin cells, aerosolized water droplets, or dust particles. In this way, the gowns, linens, surgical tables, and operating room floors are easily contaminated, particularly with staphylococci and enterococci, which are resistant to desiccation.

Despite the numerous potential causative agents of SSIs enumerated above, the predominant pathogen responsible for infection in clean skin surgery is S. aureus and its source is most frequently the patient's anterior nares. Of the US population, 31.6% are nasal carriers of S. aureus at any given time, and nasal carriers have a 3–9.6-fold increased risk of SSIs. Furthermore, among patients who develop staphylococcal SSIs and are also nasal carriers, 85% of isolates are genetically identical between the two sites, confirming the endogenous nature of the SSI.

Surgical site infection

The CDC defines SSI as any surgical wound that produces pus (suppurates) within 30 days of the procedure, even in the absence of a positive culture. An exception to this rule would be a suture abscess, which may suppurate but which resolves with the removal of the suture and is not considered to be a wound infection. Inflammation is frequently associated with wound infection but, in the absence of suppuration, is not sufficient to classify the wound as infected. A positive culture does not necessarily confirm a wound infection, because chronic wounds may be colonized but not infected. In this case, it is the quantity of bacteria per gram of tissue (usually >10 ⁵ ) that determines whether infection is present.

Categories of risk

The risk for developing an SSI can be categorized by the degree of contamination within the wound. Wounds are defined as clean if they are elective incisions carried out on non-inflamed tissues under strict aseptic technique and if there is no entry into the gastrointestinal, respiratory, or genitourinary tracts. If there are minor breaks in aseptic technique, or entry into the gastrointestinal, respiratory, or genitourinary tracts, the wound is considered to be clean-contaminated. Contaminated wounds include those where major breaks in aseptic technique have occurred, or there is inflammation, but no frank purulence encountered. A dirty wound contains frank purulent fluid such as an abscess. It may also involve the perforation of a viscus or fecal contamination.

In addition to the local condition of the wound, patient and operative characteristics may influence the risk for developing an SSI. For example, biopsies performed in a hospital ward, as opposed to an outpatient setting, have a higher risk for infection. A comprehensive method, such as that proposed by the CDC, incorporates additional factors such as the patient's age, malnutrition, obesity, hypothermia, use of immunosuppressants (including alcohol), and the length of the procedure.

Principles of Aseptic Technique

In its Guideline for Prevention of Surgical Site Infection , the CDC exhorts that “rigorous adherence to the principles of asepsis by all scrubbed personnel is the foundation of surgical site infection prevention.” However, the need for strict aseptic technique during clean dermatologic surgery has been called into question. For example, infection rates using non-sterile gloves for Mohs surgery are low and comparable with those using complete sterile technique. In reality, a wide range of “clean” and “modified sterile” techniques are commonly employed for most dermatologic procedures. As the complexity and invasiveness of the procedure increases, so does the need for adherence to strict surgical asepsis. This chapter will discuss the proper execution of both clean and sterile techniques in dermatologic surgery in the office setting, focusing on those key principles that are generally applicable to dermatologic surgeons.

Aseptic technique involves preoperative preparation to create a sterile field and then maintenance of sterility throughout the procedure. Creation of a sterile field is comprised of three elements: (1) preparation of the surgical personnel, (2) preparation of the patient, and (3) preparation of the instruments and operating environment. The first two of these necessitate the use of antiseptic agents, which will be reviewed first.

Antiseptic agents

The ideal antiseptic agent should be broad-spectrum, non-irritating, fast-acting, and provide continued antimicrobial action within the moist environment of the surgical glove. There are several commercially available antimicrobial ingredients approved for either surgical hand antisepsis, surgical site preparation, or both. Each agent has its own unique characteristics and action spectrum but none is ideal for every situation. A thorough working knowledge of the strengths and limitations of these ingredients is essential to choosing the appropriate agent for each setting ( Table 2.1 ).

Table 2.1

Common antiseptic agents

Adapted from Wade and Casewell and Parienti et al.

Agent	Action spectrum ^a	Rapidity of onset	Sustained activity	Cautions
60–95% Alcohols	++++ Gram-positive ++++ Gram-negative +++ M. tuberculosis +++ Fungi +++ Enveloped viruses	Fastest	Minimal as a single agent	Flammable Poor cleansing agent Use liberal amount and allow to dry
Chlorhexidine gluconate	++++ Gram-positive +++ Gram-negative + M. tuberculosis ++ Fungi +++ Enveloped viruses	Fast	Excellent Additive effect with repeated use	Ocular toxicity with conjunctivitis and severe corneal ulceration Ototoxicity
Povidone-iodine	++++ Gram-positive +++ Gram-negative +++ M. tuberculosis +++ Fungi +++ Enveloped viruses	Fast	Intermediate to minimal if wiped from the skin	Potential systemic toxicity with neonates or large body surface area Rapidly neutralized by blood, serum proteins, or sputum
Parachlorometaxylenol (PCMX)	+++ Gram-positive ++ Gram-negative ^b ++ M. tuberculosis ++ Fungi ++ Enveloped viruses	Intermediate	Intermediate to excellent depending on formulation	Poor Pseudomonas coverage as a single agent

a Spectrum of action: ++++ excellent; +++ good; ++ fair; + poor.

b Improved Pseudomonas coverage with addition of chelating agent such as EDTA.

In the USA, the most common agents are iodophors, chiefly povidone-iodine (PI), and chlorhexidine gluconate with and without alcohol. PI is a broad-spectrum antiseptic with well-known skin- and fabric-staining qualities. It works within minutes but must be left on the skin to have a persistent effect. It is quickly inactivated in the presence of blood or sputum, and chronic maternal use has been associated with hypothyroidism in newborns. PI is available as a 10% aqueous solution and a 7.5% foaming surgical scrub (Betadine ^® , Purdue Products L.P., Stamford, CT). The scrub contains a detergent, which should not be allowed to make contact with the eyes. Prolonged skin contact with wet PI solution can induce irritant and rarely allergic contact dermatitis but once dried, it is generally non-irritating and can be left on the skin and covered with a dressing. While approved for use on other mucous membranes, the label for PI 10% aqueous solution states “Do not use in the eyes.” Consequently, Alcon (Fort Worth, TX) markets a specific ophthalmic preparation of PI (Betadine ^® 5% Ophthalmic Prep Solution). However, 10% PI solution diluted 1 : 1 with normal saline is commonly used off-label for surgical antisepsis of the conjunctiva and periocular skin. This approach is based on extensive safety and efficacy data for bacterial endophthalmitis prophylaxis in cataract surgery. It is felt that the full strength 10% PI solution causes conjunctival irritation but direct comparative data is lacking.

Chlorhexidine gluconate (CHG) has a similar antimicrobial spectrum as PI. CHG binds to the stratum corneum and maintains residual activity in excess of 6 h, even when wiped from the field. Its action is not affected by the presence of organic matter, but it should be used with caution around the eyes, as it can cause conjunctivitis and severe corneal ulceration (see below). CHG can also induce ototoxicity if allowed to reach the middle ear through a perforated tympanic membrane. Animal studies and human case reports describe resultant deafness from prolonged exposure of CHG to the middle ear. Application to the pinna and even the external auditory meatus does not pose a risk to patients with an intact tympanic membrane but, as the status of the membrane is generally unknown, it is prudent to avoid dripping the solution into the auditory canal. CHG comes in a wide variety of strengths and formulations, the full menu of which is beyond the scope of this chapter. The most common formulation in dermatologic use is the 4% scrub solution (Hibiclens ^® , Mölnlycke Health Care, Norcross, GA or generic equivalents), which is used for surgical hand scrub as well as skin preparation.

Both CHG and iodophors are available in alcoholic solutions (ChloraPrep ^® , CareFusion Corporation, San Diego, CA and DuraPrep ^® , 3M, St. Paul, MN), which are FDA approved for one-step preoperative skin preparation. DuraPrep ^® was approved in 2006 and contains iodine povacrylex, an iodophor related to PI but with 74% isopropyl alcohol and more persistent activity as per its manufacturer. ChloraPrep ^® , approved in 2000, contains 2% CHG in 70% isopropyl alcohol. The addition of alcohol, a broad-spectrum antiseptic in its own right, greatly increases the speed of action, while maintaining the residual activity of the antiseptic. These one-step agents are only available packaged in single use applicators, which has limited their routine use in dermatologic surgery, but they are widely used in hospitals. Alcohol is irritating to mucous membranes and therefore these agents must be used cautiously around the eyes or mouth.

While available data supports the use of both PI and CHG, whether either agent provides superior SSI prophylaxis over the other remains an open debate. An influential randomized trial found preoperative skin preparation with CHG-alcohol decreased SSIs after clean-contaminated surgery by 41% compared with a traditional PI scrub and paint. Other studies have also shown superior results with CHG-alcohol. However, these studies have been criticized for comparing a combination of two potent antiseptics (alcohol and CHG) with a single agent (PI). Indeed, some studies of iodophor-alcohol combination products have shown similar antimicrobial efficacy to CHG-alcohol. In a prospective randomized study relevant to dermatologic surgery, Veiga and colleagues compared the outcomes of PI-alcohol and CHG-alcohol solutions when used prior to clean plastic surgery. CHG-alcohol significantly reduced bacterial colonies at the end of surgery and also reduced SSIs, although not quite to the level of statistical significance ( p = 0.06). While the results overall are conflicting and complicated by the use of varied antiseptic formulations in non-standardized situations, the overall weight of the evidence tends to favor a slight superiority in infection control for CHG over PI. Furthermore, CHG or iodophor-alcoholic formulations are likely superior to their aqueous counterparts and might be preferable for dermatologic surgery in areas prone to higher rates of infection such as the groin or lower leg.

Preparations with alcohol as the sole antiseptic agent are the standard of care in Europe for surgical hand antisepsis and are gaining popularity in the USA. Multiple studies have confirmed their safety, speed, and broad range of antimicrobial activity. Alcohol-based solutions do not necessarily have detergent qualities and should only be applied to clean skin and fingernails. Alcohol-containing products are highly flammable and should be allowed to dry before electrocautery or a laser is used ( Figs 2.1 , 2.2 ). When applied as a single agent, alcohol is rapidly germicidal, but once evaporated, it does not have significant residual activity. For this reason, alcohol as a single agent is not commonly used for preoperative skin preparation for sterile procedures, although it is an excellent option for surgical hand antisepsis.

FIGURE 2.1, A 70% isopropyl alcohol pad igniting seconds after contact with electrocautery tip.

FIGURE 2.2, The same type of alcohol pad as used in Figure 2.1 but allowed to dry. It does not ignite despite prolonged contact with the electrocautery tip and maximum settings.

Parachlorometaxylenol (PCMX), also known as chloroxylenol, has good Gram-positive bacteria coverage but notably poor activity against P. aeruginosa . To address this limitation, several PCMX formulations have either an added chelator, such as ethylenediaminetetraacetic acid (EDTA) or a quaternary compound, which markedly increase the anti- Pseudomonas activity of the mixture. For example, Techni-Care ^® (Care-Tech ^® Laboratories, Inc., St. Louis, MO) contains PCMX with the quaternary compound cocamidopropyl PG-dimonium chloride phosphate and claims a 99.99% reduction in P. aeruginosa within 30 s of contact. PCMX alone maintains residual activity for several hours, but this is less than that induced by CHG. It is minimally affected by the presence of organic matter and, although it can be absorbed through the skin, adverse reactions are rare. In general, relative to the other agents discussed, there is little efficacy data on PCMX with meaningful clinical endpoints and few comparative studies exist. One study that examined bacterial reduction after prepping the foot with PI, ChloraPrep ^® , or Techni-Care ^® found the highest positive culture rate with Techni-Care ^® and the lowest with ChloraPrep ^® . As of the time of this writing, Techni-Care ^® had not achieved FDA approval.

Preparation of surgical personnel

Surgical hand antisepsis

The surgeon's hands and forearms, along with those of assisting personnel, are placed in close contact with the surgical wound and represent a significant potential source of contamination. The surgical scrub serves to decrease this risk by removing transient flora and soil from the fingernails, hands, and forearms. Traditionally, this has involved a 5–10 min vigorous scrub of these areas using brushes impregnated with PI or CHG. However, recent studies have refuted the need for this approach. A landmark randomized cluster trial in 2002 demonstrated that the use of an alcohol-based hand rub was equivalent to a traditional surgical scrub in the prevention of SSIs. Numerous other studies and a 2008 Cochrane review have provided additional support for alcohol-based hand rubbing protocols, demonstrating equal or superior sustained microbiologic reduction compared with traditional scrubbing techniques. Furthermore, the alcohol-based solutions are more rapid and better tolerated by surgical personnel. A typical protocol involves removing any visible debris with a single 1 min handwash with non-antiseptic soap at the beginning of the day. This is followed with two applications of an alcohol solution (~4 mL total) to the forearms and hands prior to every procedure or whenever changing gloves. The solution should be allowed to air dry for about a minute before donning gloves.

This simple alcohol-based protocol is sufficient to meet FDA standards for the hospital operating room environment, and, although specific studies do not exist, its efficacy, speed and simplicity lend themselves to dermatologic surgery as well. At this time, evidence does not currently support any particular formulation over another. Any of the alcohol hand sanitizers routinely available in most healthcare settings should be adequate.

Antiseptic solutions can become contaminated and support microbial growth. To limit this risk, they should be stored in closed receptacles. Since the outer surfaces of a hand pump are easily contaminated, many surgeons prefer single-use packets or a foot-operated dispensing system. Another potential source of contamination is the bacteriological quality of the water used to rinse the skin after completion of the hand scrub. In one modern operating room, plumbing manipulations resulted in water flowing from the surgical sink that was contaminated with Gram-negative bacteria and atypical mycobacterium. This led to an outbreak of surgical infections and illustrates that water supplies should be periodically monitored, particularly after servicing.

Fingernails should be kept short to facilitate cleaning, and artificial nails – which are known to harbor significantly more microorganisms than natural or polished nails – should not be worn during surgical procedures. There are conflicting data regarding nail polish and its effect on the surgical hand scrub. It is generally agreed that nail polish may be worn as long as it is not chipped or dark in color, potentially obscuring the presence of subungual debris. Jewelry is known to harbor bacteria beneath it and to decrease the effectiveness of the hand scrub, but it is not known whether this sequestration leads to increased risk for SSI. Despite the lack of consensus or scientific data, jewelry and long fingernails (natural or artificial) limit dexterity, increase the risk for glove perforation, and are therefore best avoided during surgery.

Surgical attire

Surgical attire can be divided into non-sterile and sterile items, each serving different functions. Non-sterile attire is designed to reduce microbial shedding from surgical personnel and subsequent contamination of the surgical environment. It consists of a scrub suit, cover gown, face mask, shoe protection, and hair cover. These items are permeable to moisture and should be changed immediately if they become wet with blood or another body fluid.

Sterile surgical attire, such as impervious surgical gowns and sterile gloves, are designed to maintain a sterile field and protect personnel from exposure to blood-borne pathogens during surgery.

Scrub suits

Scrub suits are made of loosely woven material for comfort, and serve to reduce bacterial shedding from the skin of surgical personnel. The perineum is heavily colonized and the friction generated by walking can liberate bacteria-laden skin cells into the operating room environment. A scrub shirt tucked into pants that are constricted at the waist and ankles is an efficient means of reducing perineal dispersal. Wearing a long-sleeved scrub jacket that snaps closed in the front can decrease bacterial shedding from the forearms. However, there are no scientific data to show that wearing scrub suits rather than street clothes affects the incidence of SSI. Scrub suits serve as personal protective gear but they are not impermeable to blood or body fluids. While they add to the overall hygiene of the surgical environment, they may be considered optional for minor surgical procedures. For procedures where exposure to body fluid is expected, such as liposuction, their use – along with impermeable gowns – should be strongly considered and, regardless of the apparel chosen, any item of clothing that becomes soiled during surgery should be changed immediately.

Face masks

Face masks were originally designed to limit contamination of the surgical site from microorganisms expelled by surgical personnel. The effectiveness of a face mask is defined by its shape, the materials from which it is made, and the way in which it is worn. Loose-fitting masks allow up to 40% of expired air to escape backward past the cheeks and ears, particularly when sneezing or coughing, and must be tied snuggly to be effective. At the end of each surgery, face masks should be discarded. They should not be placed in the pocket for future use or left dangling around the neck, as the inner surface of the mask becomes contaminated with expired microorganisms. Once removed, it should be handled only by the ties.

There are conflicting data regarding the ability of face masks to reduce SSI, and their necessity in the operating room has been questioned. Several clinical studies found no difference in bacterial counts or wound infection rates when surgical personnel wore face masks during surgery. It has been suggested that face masks may even increase the risk for contamination by “wriggling” around on the face and abrading skin cells into the sterile field. Studies have found a clear relationship between bacterial contamination of the surgical field and the volume at which the person speaks. Speaking in a normal tone for up to 30 min without a face mask projects relatively few bacteria. Conversely, speaking in a loud tone, even briefly, liberates significantly more bacteria – up to 1 meter away – and coughing or sneezing can propel bacteria up to 3 meters. Given these findings, it is possible that operating in silence without a mask may provide the least risk for surgical site contamination.

Caution is advised before discontinuing the routine use of face masks because it is not always known if talking will be needed during a procedure, or if an unexpected cough or sneeze will occur. A second and more important consideration is the role that face masks play in universal precautions. They not only protect the surgical wound from air-borne contamination but also serve to protect the wearer's mouth and nose from unexpected splashes of blood and body fluids.

Surgical footwear

Footwear worn during surgery should be fluid resistant and have impervious soles. It should be cleaned regularly and restricted to use in the operating room environment. These measures serve to limit contamination of the operating room floor and protect the healthcare worker from body fluid spills. If such footwear is not available, paper booties with elastic at the ankles can be worn over street shoes. These disposable covers protect the shoes from exposure to blood-borne pathogens and add to the overall hygiene of the operating room environment. However, there is little evidence that their use directly affects wound infection rates.

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