Why is it necessary to allow evaporation of skin preparation before draping?

Why the committee made the recommendations

Based on their knowledge and experience, the committee agreed that an antiseptic should be used for skin preparation before surgery. Overall, the evidence showed that chlorhexidine in alcohol was associated with the lowest incidence of surgical site infections, whereas aqueous povidone-iodine was associated with the highest incidence. An economic analysis also showed that chlorhexidine in alcohol is likely to be cost effective. Based on the evidence, the committee agreed that an alcohol-based solution of chlorhexidine should usually be the first choice when deciding which antiseptic preparation to use. However, the quality of the studies was not good enough for the committee to make a strong recommendation for the choice of antiseptic preparation.

The committee discussed that alcohol-based solutions should not be applied to mucous membranes because of the risk of burns. For surgical procedures next to mucous membranes, they agreed to recommend an aqueous solution of chlorhexidine as an option for skin preparation. Because of the limited evidence, the committee were unable to make a strong recommendation.

There was little evidence to support the use of povidone-iodine, but based on their clinical experience the committee agreed that it should be an option when chlorhexidine is contraindicated, for example, in people with hypersensitivity to chlorhexidine.

There was no evidence on the use of skin antiseptics in babies. However, the committee were aware of risks, such as burns, associated with their use in this population, and wished to highlight this. The committee noted that the MHRA has published advice on the use of chlorhexidine for skin disinfection in premature babies.

The committee also discussed that some operative procedures may require diathermy. This means that precautions must be taken when using alcohol-based antiseptic solutions because they are flammable and can result in burns. Along with using evaporation to dry antiseptic skin preparations and avoiding pooling, the committee also agreed that soaked materials, drapes or gowns should be removed before diathermy, excessive quantities of alcohol antiseptics should not be used and no excess product should be present before applying an occlusive dressing.

The committee agreed that further research is needed to establish the effectiveness of different concentrations of chlorhexidine in reducing the risk of surgical site infections. Therefore the committee made a  to examine this further.

How the recommendations might affect practice

Antiseptic skin preparation before skin incision is standard practice although the type of antiseptic used varies depending on the type of surgery.

Since some prepping agents compound chlorhexidine gluconate or iodophors with isopropyl alcohol to combine their antiseptic benefits, the cautions against alcohol's use would likewise apply to the resulting products.

The desired effect
The CDC's guideline on SSI prevention doesn't recommend one formulation over another. "No studies have adequately assessed the comparative effects of these preoperative skin antiseptics on SSI risk in well-controlled, operation-specific studies," its authors note.[1] Similarly, AORN's recommended practices on skin preparation advise only that skin preps should be selected based on their approval by the FDA and the surgical facility's infection prevention staff, their antiseptic effect and persistence, and an assessment of the patient and surgery at issue.[2]

No surgical skin prep is universally acknowledged as the most effective. "For a long while, there has been an unresolved debate over the comparative effectiveness of antiseptic agents," says Charles Edmiston, PhD, CIC, a professor of surgery and hospital epidemiologist for the Medical College of Wisconsin in Milwaukee. In his view, however, the balance of that debate may be tipping.

Three recent clinical studies and 2 instructional overviews have suggested that the ability of chlorhexidine agents to eliminate bacteria make it an ideal option for pre-operative skin antisepsis.

For a study published in last month's Journal of Bone & Joint Surgery, orthopedic surgeons from Northwestern University in Chicago randomly prepared 150 consecutive shoulder surgery patients with either 2% chlorhexidine gluconate and 70% isopropyl alcohol; 0.7% iodophor and 74% isopropyl alcohol; or a 0.75% povidone-iodine scrub and a 1% iodine paint. They found the CHG-and-alcohol solution "more effective at eliminating overall bacteria from the shoulder region."[3]

After treating 500 surgical patients with either povidone-iodine or chlorhexidine prior to their procedures, Thai researchers report in a study published in July that the chlorhexidine group showed lower rates of bacterial colonization and post-op SSIs. "Chlorhexidine antiseptic should be the first consideration for preoperative skin preparation," they assert.[4]

Noting the higher infection rates resulting from foot and ankle procedures than from surgeries elsewhere on the body, as well as the difficulty in eliminating bacteria from the forefoot, orthopedic surgeons at the University of California San Diego randomly prepped 125 consecutive patients with 0.7% iodine and 74% isopropyl alcohol; 3% chloroxylenol; or 2% CHG and 70% isopropyl alcohol. "Of the three solutions tested in the present study," they wrote in 2005, "the combination of chlorhexidine and alcohol was most effective for eliminating bacteria from the forefoot prior to surgery."[5]

Additionally, a 2007 evidence review on infection prevention practices notes that "current literature strongly suggests that chlorhexidine gluconate is superior to povidone-iodine for pre-operative antisepsis for patients,"[6] and a similar review of skin preparation studies from 2006 concludes that "the surgical site should be prepared with chlorhexidine. A second choice would be a one-step iodine application."[7]

"Povidone-iodine does have its benefits, and a broad spectrum of activity," says Dr. Edmiston. "It's taken some time, but there is great confidence in many of the modern prep products as well."

True or False Skin Prep Quiz

1. The CDC and AORN recommend a specific type of skin prep.
2. Alcohol, povidone-iodine and chlorhexidine gluconate solutions do not have the same antiseptic properties.
3. Skin preps should always be applied in a circular motion.
4. The prepping solution only needs to cover the immediate surgical site.
5. When applying a skin prep, move from the least contaminated to the most contaminated areas.
6. Surgery can begin as soon as exposed skin has been covered with prepping solution.
7. Skin preps are interchangeable for any surgery or surgical site.
8. There is no harm in using more prep than is needed.

Answers at the end of article.

Preps in practice
Continuing research on comparative effectiveness doesn't mean your facility needs to stock just 1 type of skin prep, though. "Generally speaking, the one-size-fits-all approach to preps, regardless of what effect they have on SSI prevention, is a big misunderstanding," says Ruth M. Carrico, PhD, RN, CIC, an assistant professor at the University of Louisville School of Public Health.

The right prep to use in any given situation depends on the surgical site location as well as the patient's tolerance for it, she says. As noted above, some classes of preps are harmful to certain parts of the body.[1] The ingredients in some products may also trigger allergies or skin irritation among some patients,[2] effects that Dr. Carrico says may place patients at risk for the infections the preps are intended to prevent. "You don't want patients touching the incision site," she says. "You want them to be able to leave it alone and get on with their regular activities."

No matter which product is selected for the task, "the skin prepping technique should always progress from the clean to the dirty area," says Dr. Edmiston. This advice is AORN's exception to its recommended practice of working from the incision outward, but the intent is the same: to prevent the reintroduction of microbes into less contaminated areas.[2] Similarly, used sponges or applicators should not make contact with areas they've already treated, but should be discarded in favor of new supplies if another treatment is necessary.[2]

In addition to covering the immediate surgical site, the prepped area should anticipate the possibility of shifting or enlarged drape fenestrations, extended or new incisions or the need for drain sites.[2] A sufficiently large prepped area also prevents resident and transient flora on surrounding areas of skin from migrating to the surgical site.

While it has long been recommended that prepping solution should be applied by beginning at the incision site and circling outward,[1] that rule is no longer absolute. A circular motion works well for sponges or gauze dipped into povidone-iodine solutions, but newer prep formulations require single strokes or the exfoliating friction of back-and-forth strokes for full effect, and are supplied in applicators that facilitate this technique.[8] As a result, AORN now recommends that surgical personnel consult manufacturers' directions to determine the most effective application method.[2]

"We recognize that skin is not smooth as glass," says Dr. Carrico. "If you want to be able to reach all the skin cells, you've got to apply some effort." Dr. Edmiston adds that on larger patients who have skin folds, straight strokes prep more thoroughly than circular motion does.

Safety and savings The outpatient surgery OR is a time- and cost-sensitive environment, but despite the rush, it's critical that surgical personnel let prepping agents dry completely before continuing with the procedure. Not only does the resulting contact time enable skin preps to achieve their maximum antiseptic effectiveness, but also the evaporation of alcohol or other flammable ingredients reduces the risk of a surgical fire sparked by electrosurgery or laser equipment.[2]

Fire safety is also behind the recommendation that surgical personnel avoid using more prep than is necessary and prevent the dripping or pooling of solution beneath patients and equipment close to their skin, such as pneumatic cuffs. Prolonged exposure to large amounts of prep may also cause chemical burns.[2]

Overall, says Dr. Edmiston, "the skin prepping agent should have the following properties: fast-acting, persistent, have a cumulative activity and be non-irritating." When those factors are satisfied, says Dr. Carrico, consider convenience and your workflow. "This is going to be a staple in your surgery center," she says. "What allows you to move patients through quickly?"

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