Aims of surgical antisepsis
All skin, whether it is the skin of the patient or of the surgical team, contains some level of normal flora. The goal of surgical antisepsis is to use pre-operative handwashing, localized patient skin preparation, and topical antimicrobial products to reduce transient and resident flora to the fullest extent possible and maintain this state for the duration of the procedure.
It's impossible to achieve complete surgical antisepsis. Studies have shown that even the most active antiseptics lose their antimicrobial activity over time. The longer the procedure, the higher the incidence of post-op infection. The infection rate for a clean procedure (a procedure that does not involve a high degree of contamination or pathogens, such as bowel surgery) roughly doubles for every hour of operating time. Longer procedures also involve more complexity and a greater likelihood that foreign bodies will be inserted into the wound.
There are several patient-related factors that have been associated with an increased risk of wound infections. Special effort needs to be given to patients who are obese, over the age of 65, are malnourished, or have diabetes.
The role of the skin
There are two types of skin bacteria: transient and resident. Skin is a multi-layered surface with irregular pits, crevasses, and ridges, covered by epithelial cells that are loosely attached to the deeper cell layers. This is a great nesting place for the resident bacterial flora as well as a home for transient microorganisms being carried to the skin by airborne particles. The surface is interrupted by the opening of sweat glands and pilosebaceous units. Because sweat is sterile and flows continually, it keeps the sweat glands clean. The sebaceous glands, however, contain fatty and proteinaceous material as well as salts that can serve as nutrients for the resident flora.
An important function of the skin is to serve as a barrier to infection. Therefore, any attempt to "sterilize" the skin cannot be toxic, cause adverse skin reactions, or in any way interfere with the normal protective function of the skin. The best we can hope to accomplish is to reduce as much flora as possible with an agent that is effective in reducing the count without damaging the skin.
Efforts to improve hand condition are important because skin damage can change microbial flora. Such efforts should include assessing and monitoring hand care practices, developing formal policies for skin protectant products, and using powder free and latex free gloves.
Antisepsis is more or less successful on unbroken skin; however, its use on exposed open wounds and burns is more problematic. When you use antimicrobial chemicals on broken skin, the tissue absorbs it more readily, and bodily fluids can dilute the antiseptic effects. In addition, commonly used disinfectants have the capacity to not only injure the infectious organisms but also the viable human tissue.
Some of the newer antiseptics are being recommended for use not only on intact skin but also for use directly in wounds. However, applying antiseptics to open wounds is a risky procedure. There is always the possibility that more harm will come to the host cells than is gained by the eradication of bacteria or fungi. There is an old maxim that you should never put anything into a wound that you would not put in your eye. Systemic antibiotics are a much better choice to prevent surgical infection as well as treat local infection.
While still susceptible to invasion via bacteremia, closed surgical wounds that remain dry are immune to invasion by bacteria. It is the weeping, discharging wound that is in most jeopardy. Surgical wounds cause post-op infections by leakage from an internal suture line that allows infective material to gain access to the wound. It's vital to keep these wounds dry and covered with sterile dressings.
Handwashing and nail care
Handwashing and preoperative scrubbing is a symbiotic ritual performed in every modern OR suite. How it should be done, for how long, and with what antiseptics has been debated and studied ever since it began.
The Centers for Disease Control and Prevention (CDC) has updated its 15-year-old guideline for handwashing. Its Draft Guideline for Hand Hygiene in Healthcare Settings is currently in the process of reviewing comments (the comment period expired on Dec 24, 2001). The Guidelines focus on the use of waterless, brushless antiseptic agents and concludes that the alcohol-based handrubs:
- reduce bacterial counts on hands more effectively than plain or antimicrobial soaps;
- can be made more accessible than sinks or other handwashing facilities; and
- require less time to use and cause less skin irritation and dryness.
The CDC recommends all members of the surgical team keep their fingernails short and not wear artificial nails. Short nails are important because most hand flora are found under and around the fingernails, plus long nails have the potential of puncturing surgical gloves. Artificial nails have also been associated with higher bioloads than natural nails, and acrylic nail extensions have been linked to nail bed infections. There has been documented transmission of infections from nurse to patient caused by artificial nails. Nail polish that has been recently applied and is not chipped or worn can be allowed, although there is a potential problem of it covering subungual dirt or nail infections.
With regard to surgical hand antisepsis, the CDC's draft guideline recommendations are to:
- use either alcohol-based handrubs or an antimicrobial soap before donning gloves; and
- decontaminate hands without a brush to reduce the number of hand bacteria while minimizing skin damage.
Never use surgical scrubs with a brush; this causes a significant increase in microorganism shedding and higher skin damage. Your protocol should include two 1.5-minute applications of an alcohol-based surgical hand scrub formulation without a brush, with a concentrated focus on the subungual and interdigital spaces. This protocol produces antimicrobial activity better than or equivalent to that attained by the more rigorous and destructive use of a brush and povidone iodine or chlorohexidine formulations.
Patient skin preparation
The practice of using a razor to remove hair from the patient the night before the operation has been reported to have an adverse effect on the skin of the patient, making him more susceptible to infection. It is amazing that surgeons continue to call for razor-shaving of surgical sites despite the preponderance of evidence that it severely damages the skin.
If you must shave patients at all, do it as close to the time of surgery as possible, in a room outside the surgical suite. Make this procedure a matter of facility policy, rather than surgeon preference. Electric clippers with a disposable head are the preferred method, or if the hair is not a hindrance in any way to the effectiveness of the procedure, leave it alone.
Halogenated antiseptics such as iodophores and chlorohexidine gluconate are the chief pre-surgical scrubs used today along with the newer povidone iodine gel alcohol and chlorous acid products. Whatever the agent you choose, it should:
- significantly reduce microbial counts on intact skin;
- contain a non-irritating, safe antimicrobial preparation that maintains the skins integrity;
- be broad-spectrum;
- be fast-acting and/or have residual effect; and
- be cost-effective to use.
There is no consensus on the amount of time required for an effective skin prep. What is clear is that the scrub should be at least two minutes and that scrubs longer than five minutes may do more harm than good. This applies to hand scrubs as well as skin prep sites. The area of the skin prep should be wide enough to include the surgical site and enough of the surrounding area to prevent migration of microorganisms from the non-treated areas. Generally speaking (depending upon the patient, the location of the surgical site, etc.), the longer the procedure, the greater the area that needs to be treated.
The use of a transparent film barrier is controversial and should not be practiced without significant unbiased evidence of its effectiveness. Studies have shown that antiseptic-treated versus untreated adhesive drapes were equally ineffective at preventing clinical infections and, of course, these adhesive drapes are more expensive than conventional drapes.
Skin preparation practices continue to be rife with ritual and unsubstantiated effectiveness. A causal link between specific practices and the risk of infection is difficult to make. These practices need careful evaluation based on scientific, unbiased research.
Minimally invasive surgery has a proven record of reducing the amount of time the patient is subjected to environmental contamination. First proven effective in cholecystectomies, it is now being used in high-risk procedures such as total hip implants and closed-chest robotic-assisted heart surgeries. Smaller incisions and shorter procedure times contribute to fewer post-op infections. During any procedure, however, it's important to observe certain environmental and personal protection precautions.
The quality, quantity and movement of the air in the operating room is a contributing factor in maintaining surgical asepsis. Aerial bacterial contamination was once thought to be an important cause of surgical wound infection, but with the advent of skin and surgical instrument disinfection and sterilization, air lost its prominence as a significant factor. The primary aerial contamination source is the shedding of skin squames, which carry bacteria, by the people moving about the operating room. Always observe these three rules:
- Don't allow anyone with an active skin infection (usually caused by Staphylococcus aureus) in the OR;
- permit as few people as possible (only those that absolutely need to be there) to enter the OR; and
- emphasize that the surgical team should restrict their movements as much as possible.
Aerial contamination is directly affected by the number of people in the room, how much they move around, and the time the site is exposed. Unpublished data from the laboratory of noted research microbiologist Dr. V. W. Greene clearly showed that 30 minutes after a sterile pack is opened, 20 percent of the sterile instruments on the back table were contaminated; within three hours this number rises to 35 percent. So much for the so-called sterile field!
Most experts agree that laminar flow units above the surgical site are indicated in orthopedic procedures, such as joint replacement, where the incision is kept open for a considerable length of time.
Environmental surfaces are rarely implicated as sources of pathogens that cause infections. The general rules to follow are to wet mop or wet vacuum (preferred) a three to four ft. perimeter around the surgical field between cases when it is visibly soiled, extending the circle to include all visible soil when necessary. Floors should be thoroughly cleaned at the end of each day.
Personal protection dos and don'ts:
There has been a lot of debate over what the surgical team should and shouldn't wear in the OR; many items that were once thought essential have now been proven to be unnecessary, and, in some cases, they could increase the risk of infection. A few examples:
- Some orthopedic surgeons use total body covering "space suits" with exhaust openings in the back to further protect the patient. They have no value for personal protection and, if the team has not used the suits previously, could increase their risk. They are also cumbersome and uncomfortable, which could make for mistakes.
- The literature is clear that shoe covers do little to protect the surgical environment and are used primarily to protect the health care worker from blood and other bodily fluids. Therefore, if you do use them, make sure they are moisture proof.
- Despite several suggestive studies, the burden of proof that masks aren't necessary to prevent clusters of infection, versus overall infection rates, remain for those who propose they aren't needed. This is a matter of common sense-the studies that suggest they aren't needed are neither plentiful nor comprehensive. The CDC recommends that masks be worn when open sterile items and equipment is present. The key to effective protection of either the patient or the health care worker is the fit of the mask. A loose fitting mask, while undeniably more comfortable, offers little or no protection.
Additionally, it should be noted that there is little evidence that jewelry is a negative environmental factor. However, once again, use common sense. A wedding ring that could puncture a glove is a good example of jewelry that should not be worn in the OR. Likewise, loose and dangling bracelets and necklaces have no place in the OR.
Sterile instruments and sites
While the number of post-op infections caused by non-sterile instruments is miniscule due to the difficulty of identifying the source of an infection, modern surgery is committed to the use of sterile instruments, sutures and dressings, and the wearing of sterile surgical gloves and gowns. I subscribe heartily to those practices.
Yet, there is a certain mysticism regarding sterility in the OR suite, as well as some glaring inconsistencies, that I need to challenge. How can you justify, for example, the use of a non-sterile laparoscope in the same procedure where you insist on a sterile knife to make the incision, sterile sutures to close the wound and sterile dressings to cover it? You insist on manufacturers certifying their sterile instruments to be free from contamination to the 10-6 level, yet no one knows what level of sterility comes from the internal sterilization function, and there is no way to measure it.
Is the sterile field really sterile? Are the fronts of gowns sterile and the backs unsterile? How do you contaminate something that is on a sterile field by placing a non-sterile item into the field? Are the edges of back table drapes only sterile down to six inches and not sterile at seven inches? One of my goals in this column is to emphasize the idea that many practices shouldn't be regarded as absolutes; rather they are general rules-of-thumb to guide your aseptic practices.
Breaks in aseptic procedures that obviously and visually contaminate a sterile site are cause for re-doing the site. But if a surgeon brushes the back of the scrub nurse's gown, do you really need to delay the procedure and put the patient at risk while the surgeon goes through the lengthy and ritualistic process of re-gowning? If the circulating nurse passes her hand over the sterile field, has it really been contaminated any more than it has already been contaminated by being open to the environment?
I don't want to unilaterally declare all these practices to be worthless because they have no scientific justification. They do establish a legitimate discipline that needs to be observed during a procedure that requires the best practice asepsis. But they need to be performed within reasonable bounds that weigh the consequences against real, not perceived, threats. It is now more appropriate than ever to devote a little of the time, money and concern spent on sterility control in the OR to spending it on optimizing patient care. The prevention of infection in surgical wounds depends upon skillful surgery, intelligent and restrained use of antibiotics, and enlightened surgical antisepsis.