Everyone knows skin prepping is one of the most important first steps to reducing surgical site infection risks, but confusion persists surrounding which prepping agent to choose and how to apply it. Recent clinical findings have attempted to provide direction, including an attention-grabbing study published in the January 7 issue of the New England Journal of Medicine that found that patients who were prepped with chlorhexidine-alcohol had nearly half as many surgical site infections (9.5%) as those prepped with povidone-iodine (16.1%). If you're trying to stay current and make sense of the latest developments in surgical skin prepping, here are 5 tips to help you navigate the ever-evolving landscape.

1. Consider chlorhexidine your default skin prep. The landmark NEJM study follows related research from the May 2005 issue of the Journal of Bone and Joint Surgery in which researchers at the University of California, San Diego, analyzed culture specimens gathered from foot and ankle surgery patients who were prepped with chlorhexidine, iodine-alcohol or chloroxylenol. According to the results, chlorhexidine was more effective in killing bacteria on the foot and ankle than were iodine or chloroxylenol. This is relevant because foot and ankle patients have a higher rate of surgical site infections than any other surgical patients.

Because of its effectiveness and the increasing evidence of its superior performance compared to other antiseptics, consider chlorhexidine your default skin prep. A chlorhexidine-alcohol solution is now considered the most widely recommended prepping agent. Since 2002, the CDC has recommended 2% chlorhexidine with 70% isopropyl alcohol as the skin antiseptic of choice prior to the insertion of vascular catheters. It has yet to release a statement for pre-surgical skin preparation. More recently, however, the National Quality Forum, in its Safe Practices 22: Surgical Site Infection Prevention, calls for the use of a chlorhexidine-isopropyl alcohol skin prep before surgical procedures.

Chlorhexidine, which works by disrupting the cell membrane of bacteria, is known for its relatively fast microbial kill, but it has another characteristic that is not as widely known: Its killing action against microorganisms remains active much longer than the killing actions of alcohol, povidone-iodine or parachlorometaxylenol (PCMX).

The CDC rates chlorhexidine as excellent against gram-negative bacteria such as Escherichia coli and salmonella, and good against gram-positive bacteria such as Clostridium difficile, Enterococcus and Staphylococcus aureus, which are the cause of 20% to 30% of surgical site infections, according to the CDC. Chlorhexidine has limited effectiveness against viruses, tuberculosis and fungi. When combined with 70% alcohol, its speed and effectiveness of action increase.

Additionally, chlorhexidine is not deactivated when it comes in contact with blood, making it an effective killing agent during surgical procedures. In addition to rating how well skin preps kill bacteria initially, the residual effective kill time is just as important — or more so — depending on the application. Ideally, as is the case with chlorhexidine, residual activity of a prepping agent should last 48 hours.

However, be aware that chlorhexidine does have its limitations. Don't use it on tender skin or on infants younger than 2 months old because it can cause burns and skin irritation. The agent may also cause irritation in areas of the body near mucous membranes and can damage the cornea if it comes in contact with the eye. Because of these known limitations, chlorhexidine should not be applied to the eyes, ears or mouth or be used before a spinal tap or other procedures where it may come in contact with the meninges.

2. Alcohol works best in combination. While alcohol is the oldest antiseptic, it's still widely used in healthcare facilities today. It provides a fast microbial kill by denaturing cell proteins, but evaporates quickly because of its low molecular weight. Alcohol's short lifespan makes it inappropriate as a standalone skin prep. When using alcohol, consider a two-step approach. Following the alcohol application, apply a longer lasting prep such as chlorhexidine or povidone-iodine. Alcohol's effectiveness makes it a good preliminary skin prep option for patients with visibly dirty skin. It cannot, however, be applied to mucosal areas because the mucus deactivates the alcohol, rendering it ineffective. Also, be aware that alcohol is flammable and should be allowed to evaporate to be most effective in killing microbes and to reduce the risk of ignition.

3. Don't discount iodine preps. Iodine kills by disrupting the cell walls in bacteria. Although chlorhexidine was shown to be more effective than povidone-iodine solutions in the NEJM study, some clinical situations still require the use of povidone-iodine. For example, use povidone-iodine around mucous membranes and on patients who are sensitive to chlorhexidine solutions and require an alternative prepping solution. Povidone-iodine has a fairly fast microbial kill after 2 minutes of drying, but has less residual activity compared to chlorhexidine. Povidone-iodine is rated excellent against gram-positive bacteria and good against gram-negative bacteria, viruses, tuberculosis and fungi.

4. Prepping without alcohol or iodine. Use PCMX when the surgical site is near the eyes, mouth or genitals, or when the patient is allergic to iodine or alcohol. PCMX disrupts cell membranes and is rated good against gram-positive bacteria and fair against gram-negative bacteria.

When prepping with PCMX, swab the prep site for 2 minutes to ensure the gel penetrates the skin. Don't use alcohol-based products around areas prepped with PCMX because alcohol can disrupt the residual effectiveness of the product. When uninterrupted, the residual effect of PCMX lasts 6 to 8 hours. Due to its limited killing and residual action, PCMX should be used only when chlorhexidine or iodine are not recommended, such as when a patient has a history of irritation with other preps.

5. Apply using friction. Although the CDC's recommendations for preventing surgical site infections call for you to prep using concentric circles beginning at the proposed incision site and working outward, this is no longer considered the only effective way to prep a surgical site.

Prepping works best with a frictional scrub, no matter what type of prep you're using. Skin is not flat; it has crevices, grooves, hair follicles and sebaceous glands, all of which act as reservoirs for bacterial breeding. Using a back-and-forth motion while using friction to apply surgical preps actually scrubs the skin and removes the external layer of bacteria. This forces the prep solution into the skin's deeper layers and cracks. As for deciding between circular and back-and-forth motions to apply preps, AORN no longer recommends using only circles. Rather, AORN's 2008 Recommended Practices for Preoperative Patient Skin Antisep-sis suggests you follow the manufacturer's instructions for application when deciding how to best apply a particular prep.

Consensus is building
The practice of prepping is constantly evolving, as evidenced by the recent research that tabs chlorhexidine-alcohol as the first-choice surgical prep based on its demonstrated superior action and residual killing power after application. The mounting clinical evidence is creating more than just buzz; a consensus is building that may forever change the rules regarding this vital part in the battle against surgical site infections.