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The Science of Skin Prepping
What does the latest literature recommend on skin antisepsis and hair removal?
David Bernard
Publish Date: January 27, 2014
skin prepping CLOTH CARE Do CHG wipes' antimicrobial effect have an impact on SSI rates?

Recent years have seen the publication of several landmark studies on pre-operative skin preparation's role in reducing bacteria and preventing surgical site infections, but these have by no means been the last word on the subject. Here's a recap of some of the latest thinking on skin prepping agents, pre-op bathing and hair removal.

The effectiveness of agents
The Darouiche study (see "Chlorhexidine-Alcohol Wins Face Off vs. Povidone-Iodine"), published in the New England Journal of Medicine 4 years ago (tinyurl.com/3alrol3), joined a quickening drumbeat of research recommending chlorhexidine gluconate for skin antisepsis before general and orthopedic surgeries due to its high antibacterial efficacy and surgical site reduction rates. Critics of the study have questioned its balance, however, since it pitted a 2% CHG and 70% isopropyl alcohol product against an aqueous solution of 10% povidone-iodine.

In "The Forgotten Role of Alcohol," published online in the journal PLoS One in September 2012 (tinyurl.com/kc98ehx), researchers from the KK Women's and Children's Hospital in Singapore pointed out this discrepancy in a range of studies. "We found good evidence favouring chlorhexidine-alcohol over aqueous competitors, but not over competitors combined with alcohols," they wrote. They also noted that several studies "attributed outcomes solely to chlorhexidine when the combination with alcohol was in fact used. ... The role of alcohol has frequently been overlooked in evidence assessments."

When even competitions can be arranged, recent clinical comparisons of skin prepping agents have seen neck-and-neck finishes — that is, if any conclusions can be reached — as shown by the following studies.

  • Citing contradictory results in studies touting the effects of CHG-alcohol products, researchers from the Washington State Surgical Care and Outcomes Assessment Program compared 4 agents — CHG, CHG with isopropyl alcohol, povidone-iodine, and iodine-povacrylex in isopropyl alcohol — on 7,669 patients in clean-contaminated surgeries at four Seattle-area facilities. As reported in the Journal of the American College of Surgeons' Nov. 27, 2013 issue, the study "did not demonstrate superiority of any commonly used skin antiseptic agent in reducing the risk of SSI, nor did it find any unique effect of isopropyl alcohol. These results do not support the use of more expensive skin preparation agents." (tinyurl.com/m84s4td)
  • One hundred consecutive patients undergoing elective lumbar spine surgeries were prepped with either a 2% CHG and 70% isopropyl alcohol solution or 0.7% iodine with 74% isopropyl alcohol by orthopedic surgeons at Northwestern University's Feinberg School of Medicine in Chicago. They found the 2 options equally effective in eliminating bacteria from the skin at the incision site, they note in the Journal of Bone & Joint Surgery's American edition in March 2012 (tinyurl.com/lcfpgjw).
  • After reviewing 13 studies involving 2,623 participants and a variety of skin antiseptics, researchers at the University of York in England saw no statistically significant differences in SSI rates between skin-prepping agents and were inconclusive as to which was most effective, or whether pre-op preparations had any effect on post-op infections at all. Some studies showed alcohol-based products as having a high probability of effectiveness, but evidence quality was low, they wrote in the Cochrane Database of Systematic Reviews in March 2013 (tinyurl.com/ml7pmkn). "Practitioners may therefore elect to consider other characteristics such as costs and potential side effects when choosing between alternatives."

Pragmatic providers have pointed out that, clinical competition aside, there's still a role for povidone-iodine as well as CHG in prepping practices. For eye, ear, head and neck surgeries, on mucous membranes, iodine can go where CHG and alcohol can't.

Wipe out infections
The Institute for Healthcare Improvement's Project JOINTS, an educational effort that aimed to reduce SSIs following orthopedic procedures (tinyurl.com/otmkt4w), recommended that patients bathe or shower with CHG soap for at least 3 days before their surgeries. CHG-impregnated wipes have made this pre-op preparation even more convenient, even if its effect is still up for debate.

Researchers concede that CHG showers reduce skin-based bacteria, but do they also reduce SSI rates? A literature review conducted at the Royal Brisbane and Women's Hospital in Australia casts doubt. Seven trials involving 10,157 participants saw no statistically significant differences in infection rates between patients washing up with 4% CHG and those using a placebo or bar soap. As in previous reviews, the authors found "no clear evidence of benefit for preoperative showering or bathing with chlorhexidine over other wash products, to reduce surgical site infection. Efforts to reduce the incidence of nosocomial surgical site infection should focus on interventions where effect has been demonstrated," they wrote in the Cochrane Database of Systematic Reviews in September 2012 (tinyurl.com/nu66dhd).

In a series of studies published last year, however, surgeons from the Rubin Institute for Advanced Orthopedics and the Center for Joint Preservation and Replacement at Baltimore's Sinai Hospital made the case that asking patients to prepare their sites with CHG is not only effective but also economical.

  • For a study appearing in the March 2013 issue of the Journal of Arthroplasty, some hip replacement patients were given CHG-impregnated cloths and instructions to wipe down the surgical site on the evening before and the morning of surgery. Others received standard, in-hospital skin prepping. The CHG-wipe group saw a 0.5% SSI rate, as compared to the non-wipe group's 1.7% rate (tinyurl.com/q4y9seq).
  • When the study was conducted among knee replacement patients (for the June 2013 issue of the Journal of Knee Surgery), the difference in SSI rates was similarly significant: 0.6% for the patients that used CHG wipes, 2.2% for the patients that didn't (tinyurl.com/kxjwbqw).
  • Accounting for surgical site infection rates and the cost of revision surgeries after knee replacement procedures, researchers determined that the pre-operative use of CHG wipes at their facility saved about $2.1 million in healthcare costs per 1,000 patients. They calculated this out to an annual savings of $780 million to $3.18 billion, according to their report in the August 2013 Journal of Arthroplasty (tinyurl.com/n6ps93e).

Hair now, gone tomorrow
The Surgical Care Improvement Project states that clippers or depilatory creams, not razors, should be used to remove hair at the surgical site, and the Association of periOperative Nurses and other organizations stress that hair removal should take place only when absolutely necessary for access.

Recent evidence-based studies have been sparse, but the November 2011 Cochrane Database of Systematic Reviews featured a survey of 14 hair removal studies of various types. Reviewers from De Montfort University and University Hospitals Leicester in England found that SSI rates were higher after patients were shaved with razors than they were after clippers were used (tinyurl.com/qjrhdy5).

They didn't see much of a difference in SSIs, though, between patients who underwent hair removal and those who didn't; between those whose hair was removed the day of surgery and those for whom it was removed the day before; or between those shaved with razors and those who used depilatory cream; although they note that many of the studies they reviewed were based on small samples. They found no studies comparing SSI rates after clippers versus depilatory creams, or when hair was removed in different clinical settings.

Chlorhexidine-Alcohol Wins Face-Off vs. Povidone-Iodine

preventing surgical site infections SUPERIOR PROTECTION Chlorhexidine-alcohol did a better job of preventing surgical site infections than povidone-iodine in one landmark study.

In a 4-year-old landmark study, chlorhexidine-alcohol outperformed povidone-iodine in preventing surgical site infections in a head-to-head comparison led by Rabih O. Darouiche, MD, professor in the center for prostheses infection at Baylor College of Medicine in Houston, Texas.

Researchers prepped 409 patients with chlorhexidine-alcohol scrub and 440 patients with povidone-iodine scrub before clean-contaminated surgeries. The application of chlorhexidine-alcohol reduced the SSI risk by 41%, compared with povidone-iodine, at 30 days post-op, according to the study, which appears in the Jan. 7, 2010, issue of the New England Journal of Medicine (tinyurl.com/3alrol3). The overall SSI rate was 9.5% in the chlorhexidine-alcohol group vs. 16.1% in the povidone-iodine group.

Both antiseptic agents possess broad-spectrum antimicrobial activity, but the researchers note that chlorhexidine-alcohol's superior protection is related to its more rapid action, residual effect and persistent activity despite exposure to bodily fluids. The study was funded by CareFusion, which makes both types of surgical prep.

Linda R. Greene, RN, MPS, CIC, manager of infection prevention at Highland Hospital in Rochester, N.Y., says her clinicians use chlorhexidine for most surgeries, particularly orthopedic and cardiac procedures. "Many clinicians have been waiting for robust evidence published in a reputable peer review journal," she says. "This randomized control study provides evidence to support the use of chlorhexidine."

The cost of chlorhexidine-alcohol is typically $7 to $10 per case, compared with less than $1 for a regular povidone-iodine paint, says Ms. Greene. She says chlorhexidine-alcohol is easy to use and quick-drying, but its application method is different than the typical prep. Rather than applying in concentric circles, it requires a back-and-forth scrubbing motion, she says. "Additionally," she says, "it cannot be used on mucus membranes because it contains alcohol, so there are limitations."

— Daniel Cook