We've long known that most surgical site infections arise from the endogenous flora of the patient's skin, mucous membranes or hollow viscera, making antibiotic prophylaxis, skin antisepsis, draping and other preventive measures "Job #1" in surgical infection control. Unfortunately, our understanding of how to prevent these kinds of infections is still evolving. What we don't know about antimicrobial prep products, systemic antimicrobial prophylaxis and draping would fill volumes. Here's what experts advise based on our understanding so far.
1. Consider Antimicrobial prophylaxis
At least for some procedures, the most important infection prevention measure may be antibiotic prophylaxis. There is unfortunately almost no way of preventing at least some organisms from entering the wound. But we can sometimes help the body's immune system overcome them.
In its "Guideline for Prevention of Surgical Site Infection, 1999," the Centers for Disease Control indicates that it has a higher level of confidence in antibiotic prophylaxis than almost any other infection control practice.
The agency recommends choosing antibiotics targeted toward the most likely organisms, timing the administration so that serum levels are at a bactericidal level during the period between the initial incision and no more than a few hours post-operatively.
The agency also counsels using this method only when appropriate, which is where the challenges come. Studies are fairly conclusive that for so-called minimally invasive procedures, such as laparoscopic cholecystectomy, antimicrobial prophylaxis does not help. The research is much less conclusive for other outpatient procedures, including hernia, reconstructive breast surgery, ear surgery and transurethral procedures. Surgical teams must make their best judgments on a case-by-case basis, using the existing research.
2. Avoid hair removal
Although surgeons have for decades dictated pre-operative shaving of the surgical site, it's almost certainly a bad idea. Shaving can cause skin abrasion and nicks, creating a passage for pathogens. In one study, SSI rates were 5.6 percent in shaved patients and 0.6 percent in patients who had hair removed by depilatory or who had no hair removed. Another study showed no increase in the infection rate when hair was left in place for scalp incisions. The patients shampooed with chlorhexidine the night before surgery. In the OR, the scalp was scrubbed for eight minutes and irrigated with alcohol. The hair was parted at the proposed incision site and tied back.
Experts say leaving hair intact greatly reduces the patients' anxiety. Hair removal is embarrassing, uncomfortaable, and a lingering reminder of the surgical experience.
Says Jan Schultz, MSN, an expert in aseptic practices in the perioperative setting: "The question is, ?How much do you need to remove for the comfort of the patient or for the convenience of the surgeon?'" If any hair is to be removed, she recommends removing only the minimal amount, just prior to entering the OR, and with clippers (never a razor). "We use clippers only, and just remove enough hair to get it out of the surgeon's way," notes Pat Metcalf, BSN, CIC, Director of Infection Control for Children's Medical Center of Dallas.
Another option, albeit perhaps not a great one, is depilatory cream. Creams do not pave the way for infection. But depending on the surgical site, depilatories can be time-consuming and tedious. Ms. Schultz points out that many patients react to depilatories, so a 24-hour patch test prior to use is recommended. Also, depilatories are not appropriate around the groin area. Remind the nursing staff to either leave any hair that failed to respond to the depilation or shorten it with clippers.
3. Use pre-op antiseptic showers
There is only limited evidence linking chlorhexidine showers to a reduced SSI rate. But we know for sure that preoperative showers reduce microbial colonies on the skin. A University of Connecticut study of some 700 patients who received two pre-op antiseptic showers with 4% chlorhexidine reduced the bacterial count on their skin ninefold (other agents, including medicated soap and water, were less effective). The study also showed that this ritual reduced wound infections as opposed to other regimens. Most experts recommend two showers of the incisional area. "We do one shower the night before surgery, and one the day of. Be sure to keep chlorhexidine out of the patient's eyes and ears," notes Ms. Metcalf.
4. Prep the site
The evidence supporting antiseptic preps as an SSI-reducing measure is also limited. However, because the skin harbors a multitude of micro-organisms, most experts believe it makes sense to reduce the population adjacent to the incision prior to surgery.
There are five basic antiseptic agents for pre-op prep of the surgical site. Though we know some of the advantages and disadvantages of each agent, we do not know for sure which is best for reducing SSIs.
Alcohol-based products are inexpensive, fast acting and germicidal against bacteria, fungi and viruses, although they do not always kill spores. A disadvantage is that alcohol is flammable. It's not to be used with electrocautery procedures.
Chlorhexidine gluconate is effective against a broad range of microbes. It also boasts more residual activity after application; the germicidal properties continue after the solution dries. It also remains active in the presence of blood or serum.
Povidone iodine, the traditional agent, is the only prep shown to reduce the incidence of endophthalmitis in cataract surgery. Otherwise, it has not performed as well as chlorhexidine in most studies. Chlorhexidine tends to achieve greater reduction in skin microflora, and have greater residual activity after a single application. Iodophors can also be inactivated by blood or serum proteins. One alcohol-based iodophor product contains a water-insoluble film; its maker believes this prolongs its killing power and helps keep it from washing away.
The Food and Drug Administration has begun regulating topical antimicrobials (as well as hand scrubs) more rigidly. Before coming to market, new products must pass a rigid battery of in vitro and in vivo testing. It's possible that more traditional products may ultimately need to pass the tests to stay on the market.
Ms. Schultz suggests selecting a prep product that:
- Is appropriate for the site. "If you are doing more than one type of surgery, you will most likely need more than one prep product," Ms. Schultz says;
- Rapidly drops microbial count;
- Has residual action;
- Is non-sensitizing;
- is reasonably priced.
Surgical facilities differ in the way they apply the products; some just paint the solution on, some apply it and then wipe it off. Because there are no well-controlled studie, it's hard to say which is most effective. The CDC offers these guidelines:
- Clean the skin to remove debris and soil.
- Apply the antiseptic in concentric circles, beginning in the area of proposed incision.
- Prepare an area large enough to extend the incision or create new ones.
Use aseptic technique when handling prep solutions, as pathogens can colonize them. The Association of periOperative Registered Nurses says to:
- Wash hands before handling prepping solutions.
- Use single-use supplies or be sure to use all solution in a small bottle and sanitize the bottle before refilling it.
- Never pour unused prep products back into larger containers or "pool" smaller amounts from different bottles.
5. Drape the Patient
Draping creates a physical barrier between the surgical field and the patient's skin. It also channels potentially contaminated fluids away from the wound.
Unfortunately, science tells us little about how to do it properly, and there are few data to tell us how effectively drapes prevent endogenous infections. More than a few studies question whether some types of draping help with infection control at all. The CDC makes almost no recommendations on draping, suggesting only that facilities use drapes impervious to liquids and viruses.
There is evidence that for high risk procedures, facilities should consider drapes impregnated with antimicrobials. However, even this area is controversial.
We know more than ever about combatting endogenous organisms, but we still don't know it all. The best course of action may be to stay abreast of science and use common sense where science fails us.
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