Abstract
Background:
Adhesion of incise drapes is important at the wound edge, where the skin and drapes are contiguous with the wound. Separation of incise drapes from the skin has been reported to be associated with a sixfold increase in the infection rate compared with surgical procedures in which the drape did not lift off. The present study sought to determine whether the choice of preoperative skin preparation affects the adhesion of various incise drapes.
Methods:
Following randomization, the backs of twenty-two healthy volunteers were prepared with two skin preparations, 3M DuraPrep Surgical Solution Patient Preoperative Skin Preparation or ChloraPrep with Tint (Scrub Teal) Patient Preoperative Skin Preparation, according to the label directions. Sample strips (12.7 × 76.2 mm) of three different drapes were applied to the prepared areas and were covered with gauze soaked with saline solution for thirty minutes to simulate a fluid challenge. Drape samples were mechanically removed with use of a peel tester based on an international standard for testing peel adhesion of pressure-sensitive tape. Adverse events were monitored and the skin condition was observed. The primary outcome was drape adhesion, measured as the peel strength in units of gram-force. Outcomes were assessed according to drape type and skin preparation with use of mixed-model analysis of variance.
Results:
Skin prepared with DuraPrep solution had significantly greater drape adhesion (mean peel strength, 181 gf) compared with skin prepared with ChloraPrep (79 gf, p < 0.001). Although maintaining good adhesion is important, an incise drape that has excessive adhesion may cause skin irritation. Regardless of the skin preparation used, the skin reaction at the application site ranged from none to moderate erythema, and in no instance constituted an adverse event that required treatment.
Conclusions:
The data suggest that the type of skin preparation affects drape adhesion. For surgical procedures in which incise drapes are used, choosing a skin preparation that enhances drape adhesion may minimize drape lifting and the potential for wound contamination.
Level of Evidence:
Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.
According to the Centers for Disease Control and Prevention’s National Nosocomial Infections Surveillance System reports, surgical site infection is the third most frequently reported type of nosocomial infection among hospitalized patients1. Wound contamination increases the likelihood of wound infection2,3. Patient safety in the operating room is a critical issue globally, and health care providers have incorporated measures such as antimicrobial prophylaxis, mitigation of predisposing patient and surgical characteristics, and techniques for reducing wound contamination4. The strategies directed at reducing the skin microbial count and protecting the wound from contamination include preoperative bathing, use of preoperative skin preparation, and use of surgical incise drapes.
For most surgical site infections, the source of pathogens is the endogenous flora of the patient5-7. Skin antisepsis prior to surgery remains a standard practice. However, skin preparation only reduces the number of bacteria on the skin, and some residual bacteria may persist. Residual skin flora can also replicate or multiply during surgery8, and bacteria on surrounding skin may contaminate the surgical wound during the procedure, particularly during surgical procedures in which irrigation fluids are used. Adhesive incise drapes are often applied at the beginning of a procedure as an additional intervention to reduce the risk of wound contamination from the patient’s skin by providing a physical sterile barrier between the surrounding skin and the open wound. However, in order for an incise drape to be effective, it needs to remain securely adhered to the skin, including at the wound edge where the skin and drape are contiguous with the wound, during the entire surgical procedure. Drape lifting or drape pull-back from the wound edge may allow organisms on the skin to contaminate the wound. In one laboratory study, it was shown that bacteria did not multiply underneath a plastic adhesive drape within the time periods studied and that lateral migration of bacteria did not occur9. Alexander et al. concluded that separation of incise drapes from the skin was associated with a sixfold increase in the infection rate compared with surgical procedures in which the incise drape did not lift10.
Several skin preparations based on chlorhexidine gluconate or iodine in conjunction with isopropyl alcohol are commonly used during surgery. Because of the increase in the number of different skin preparations and incise drapes currently available for use in clinical practice, it is important to know whether particular skin preparations affect adhesion of drapes to the skin. This study sought to determine the effect of skin preparation on the adhesion of various incise drapes to the skin in an environment simulating the intraoperative use of wet saline solution.
We compared the two alcohol-based single-step skin preparations that are most commonly used in operating rooms in the United States, 3M DuraPrep Surgical Solution (Iodine Povacrylex [0.7% available iodine] and Isopropyl Alcohol, 74% w/w) Patient Preoperative Skin Preparation (3M, St. Paul, Minnesota) and ChloraPrep with Tint (Scrub Teal) 2% w/v chlorhexidine gluconate (CHG) and isopropyl alcohol (IPA) Patient Preoperative Skin Preparation (CareFusion, San Diego, California). The active ingredients in ChloraPrep and DuraPrep are chlorhexidine gluconate-isopropyl alcohol and iodine povacrylex-isopropyl alcohol, respectively. DuraPrep solution contains a polymer that dries to a water-insoluble film11.
Three incise drapes commonly used in the United States were selected for the study. One was an incise drape with no antimicrobial agent, 3M Steri-Drape 2 Incise Drape (3M), and the other two were incise drapes containing an antimicrobial agent, 3M Ioban 2 Antimicrobial Incise Drape (3M) and ACTI-Gard Antimicrobial Incise Drape (Medical Concepts Development, Woodbury, Minnesota). Drape samples were applied on the backs of healthy volunteers (eleven men and eleven women aged eighteen to sixty-five years).
This study was conducted by an independent testing laboratory (cyberDERM Clinical Studies, Broomall, Pennsylvania) following institutional review board approval. Volunteers signed an informed consent form and were enrolled in the study if they had no sensitivities or allergies to adhesive products or antimicrobial agents and no existing health conditions that would put them at increased risk during the study (e.g., diabetes, pregnancy or nursing in women, skin conditions on the back, or immunosuppression therapy). The study involved a screening visit within one week prior to the start of the study followed by a study visit that took place during a single day.
Sample Application and Peel Test
Subjects were asked to refrain from using skin products on their back during the twenty-four hours prior to the study visit. Prior to application of the test materials on the study day, a clipper was used to remove excess hair from the test site if necessary. Either DuraPrep or ChloraPrep solution was applied to the right side of the back according to a computer-generated randomization schedule, and the other solution was applied to the left side. Each subject was tested with both skin preparations simultaneously, and the solutions were applied according to the label directions for a dry site.
The prepared sites were allowed to dry, and 12.7 × 76.2-mm sample strips of each of three incise drape products (Ioban, Steri-Drape 2, and ACTI-Gard) were then applied. A total of eighteen drape sample strips (three strips of each test drape type on each side of the back) were applied to each subject, with the long axis of each sample oriented perpendicular to the subject’s spine as shown in Figure 1. A 2.7-kg roller was rolled over the sample strips to ensure consistent and adequate adherence to the skin.
Drape samples were then soaked for thirty minutes by placing gauze saturated with saline solution over the test strips. The gauze was resaturated every ten minutes with additional saline solution. After the thirty-minute saline solution challenge, the gauze was removed and each sample was assessed for drape lifting. Drape lifting, for the purpose of this study, was defined as separation of the drape sample from the skin. Samples were then mechanically removed from the skin using a peel tester constructed for this purpose. The peel tester measured the peel force required for drape removal according to a modified technique based on an international standard for peel adhesion testing of pressure-sensitive tape12. For this study, the drape samples were peeled at a 90° angle to the skin (Fig. 2). The direction of the pull was perpendicular to the spine, starting at the medial edge and proceeding laterally. The adhesive drape samples were peeled at a rate of 30.5 cm/min. The greatest instantaneous peel force during strip removal (defined as the peel strength) was recorded. A detailed description of the peel tester is given in the Appendix.
The occurrence of adverse events and the skin response were monitored during the study. After removal of the drape samples, each test site was assessed to determine the skin condition (temporary redness and skin stripping) according to the following erythema and edema severity scale: 0 = none; 1 = mild response, slight erythema; 2 = moderate response, confluent erythema; 3 = marked erythema, slight edema; and 4 = severe erythema, edema, possible erosion. This visual scale was established by the 3M Health Care Clinical Research Department on the basis of confidential in-house information. Transient erythema observed for no longer than five minutes after adhesive drape removal was not considered an adverse event. The skin reaction was graded by a technician trained in clinical assessment of skin condition, supplemented when needed by an expert grader with over twenty years of skin assessment experience.
Statistical Methods
A sample size of eighteen subjects and eighteen drape samples per subject resulted in fifty-four samples per drape per skin preparation. This provided 80% power to detect a difference of 20% in the comparisons among drapes, and it provided 85% power to detect a difference of 20% in the comparisons between skin preparations. We planned to enroll at least twenty subjects to ensure that eighteen subjects completed the study. The primary outcome variable was the peel strength. The study used a randomized block design. A mixed-model analysis of variance (ANOVA) was used for the data analysis, with subject and subject interactions as random effects. Analyses were conducted with drape type and skin preparation type. For the comparisons between skin preparations, a two-tailed p value of <0.025 was considered significant. For the comparisons among drapes, a two-tailed p value of <0.017 was considered significant. If significant differences existed in the comparisons between preparations, these were assessed with use of the Tukey-Kramer test for multiple comparisons. The secondary outcome variable was the skin condition assessment; this score was considered nonparametric, and the Friedman ANOVA test with Dunn multiple-comparison analysis was used.
Source of Funding
This study was financially sponsored by 3M Health Care, St. Paul, Minnesota, of which one of the authors is an employee.
Twenty-four subjects were screened, and twenty-two were eligible for enrollment and completed the study. One minor protocol deviation occurred: the randomization was unintentionally reversed for the application of the skin preparations on the back of one subject. The data from this subject were included in the data analysis.
Peel Strength
When data for all drape types were combined, drape samples applied to the sites prepared with DuraPrep solution had significantly greater peel strength (mean, 181 gf) compared with drapes applied to the ChloraPrep sites (mean, 79 gf; p < 0.001). Each individual drape type also demonstrated significantly greater peel strength on sites prepared with DuraPrep solution compared with sites prepared with ChloraPrep (194 compared with 110 gf for Ioban, 176 compared with 65 gf for Steri-Drape 2, and 173 compared with 61 gf for ACTI-Gard; p < 0.001 for all) (Fig. 3).
The results of the Tukey-Kramer multiple-comparison analysis indicated that Ioban drapes had significantly greater peel strength than either of the other two drape types, regardless of the skin preparation used (p < 0.001 for both skin preparations). The peel strength of Steri-Drape 2 did not differ significantly from that of ACTI-Gard on skin treated with either preparation (p > 0.05 for both).
Skin Assessment
No adverse events occurred during the study. The most severe skin reaction observed at any test site was moderate erythema (a skin score of 2). There were no instances of marked erythema or skin stripping.
On the basis of the Dunn multiple-comparison analysis, two of the three drape types tested had a significantly higher mean skin condition score on the DuraPrep solution sites than on the ChloraPrep sites (0.95 compared with 0.30 for Steri-Drape 2 and 0.90 compared with 0.32 for ACTI-Gard, respectively; p < 0.01 for both). The mean skin condition score for Ioban did not differ significantly between the DuraPrep solution sites (0.98) and the ChloraPrep sites (0.67, p > 0.05) (Fig. 4).
One Steri-Drape 2 sample on a ChloraPrep site demonstrated drape lifting from the skin after the thirty-minute saline solution challenge prior to mechanical removal from the skin.
In the operating room, the type of skin or integument at surgical sites varies depending on anatomic location. There is currently no single skin preparation that has been universally recommended for all surgical sites13-15. In a prospective experimental study, Swenson et al. compared three skin preparations: povidone-iodine scrub paint with isopropyl alcohol, chlorhexidine gluconate-isopropyl alcohol, and iodine povacrylex-isopropyl alcohol. They concluded that an iodophor skin preparation may be superior to chlorhexidine gluconate-based compounds for reducing the rate of surgical site infection in patients undergoing general surgery16. In another randomized prospective study, Darouiche et al. reported a significantly lower surgical site infection rate in patients who underwent clean-contaminated surgery after preparation with chlorhexidine gluconate-isopropyl alcohol compared with aqueous povidone-iodine17. However, in letters to the editor, Riccio et al. and Swenson and Sawyer disputed the conclusion of the Darouiche study by noting that alcohol is a powerful antiseptic18 and argued that excluding alcohol in one of the two treatment arms (aqueous povidone-iodine) weakened the applicability of the study19.
Many surgeons choose to use surgical incise drapes on prepared surgical sites to provide added protection. By design, an incise drape with a pressure-sensitive adhesive adheres to the skin and provides a sterile barrier at the beginning of a surgical procedure. Since surgical incise drapes were first described over fifty years ago20, there have been conflicting conclusions regarding their value in preventing surgical site infection. In a retrospective study, Yoshimura et al. found that not using an iodophor-impregnated incise drape was one of the factors that was significantly associated with postoperative surgical site infection in patients who underwent liver resection for hepatocellular carcinoma21. In a prospective randomized study, Chiu et al. concluded that there was no difference between the wound infection rates after operative treatment of acute hip fractures with and without use of plastic incise drapes22. In a Cochrane Review, the evidence suggested that intraoperative use of incisional adhesive drapes is unlikely to reduce the surgical site infection rate and may in fact increase it23. That review included seven studies that covered a twenty-five-year time span (1977 to 2001); five studies involving 3082 participants compared adhesive drapes to no drapes, and two studies involving 1113 participants compared iodine-impregnated adhesive drapes to no drapes. The review combined a wide range of surgical procedure types (caesarean sections and general, abdominal, and hip fracture procedures) in the analysis. It was recommended that a large, high-quality randomized controlled trial be performed to determine whether or not modern adhesive drapes reduce the rate of surgical site infection.
It would be desirable to obtain clinical evidence in the form of a prospective randomized controlled trial that validates the use of skin preparation and incise drapes to reduce the surgical site infection rate. Such a study, duly stratified according to surgical site infection risk, comorbidities, and length of surgery, may not be practical to perform for clean or clean-contaminated wound classifications in a surgical specialty such as orthopaedics. To have an 80% chance of demonstrating (at the p = 0.05 significance level) that a surgical intervention reduces a 1% infection rate by one-fourth, 44,000 cases would be needed. In addition, if surgeons have been using incise drapes to provide protection in their clinical practice, excluding the use of incise drapes for patients in a clinical study would be a deviation from their standard of care, which many surgeons would be unwilling to do.
The present study was designed to determine whether the choice of skin preparation affects how well a drape adheres to skin as intended. It is logical to assume that a drape that adheres well to the skin during surgery provides added protection against potential wound contamination. This study demonstrated that all three incise drapes that were tested adhered significantly better to skin when used in conjunction with DuraPrep compared with ChloraPrep skin preparation. The study was conducted in a controlled laboratory setting and was designed to simulate a fluid-saturated environment similar to the environment that occurs during surgery. Although this study was not conducted in an operative setting, it was designed to use a validated, standardized peel strength test for measuring adhesion to skin. Thus, the data obtained here do provide a reliable measure of the differences in adhesion of various test drapes to skin prepared with either of the two investigated skin preparations. This suggests that performance variations may exist among other skin preparations as well, which may warrant further study. Additionally, studies to determine whether similar performance variations occur in the operative setting would help to better define whether a specific skin preparation is necessary to optimize the performance of adhesive drapes and hence their contribution to reducing the risk of wound contamination.
Although maintaining drape adhesion to skin during a surgical procedure is important, adhesion that is too aggressive may cause skin stripping and/or skin irritation on removal. Therefore, skin assessments were performed as part of the study to observe the transient reaction of the skin within five minutes of drape sample removal. The observed skin reaction ranged from none (a skin score of 0) to moderate erythema (a skin score of 2), regardless of the skin preparation used. Transient erythema observed for no longer than five minutes of adhesive drape removal was not considered an adverse event. The most severe skin reaction observed on any test site was transient moderate erythema. For two of the three drapes, the mean skin condition score following removal of the drape samples was significantly higher on skin sites prepared with DuraPrep solution compared with ChloraPrep (p < 0.01 for both). However, the skin condition scores remained in a range that was not considered to represent an adverse event.
One limitation of the present study is the fact that adhesion was tested only for samples applied to a flat area of the body (i.e., the back); adhesion was not assessed on contoured areas such as the shoulder or knee. Similarly, samples were not tested in an operative setting, in which the skin may be retracted or otherwise manipulated. The study was focused on the relative adhesion of different samples under similar conditions rather than on absolute adhesion values. The clinical importance of the reported significant differences in peel strength remains to be established, since we are presently aware of no information regarding a relevant performance threshold for drape adhesion (i.e., the peel strength needed to avoid loss of incise drape adhesion in the intraoperative setting).
In conclusion, the results of this study demonstrate that the adhesion of incise drapes to skin may be affected by the type of skin preparation used for the surgery. The choice of skin preparation is an important consideration in ensuring that the adhesive incise drape remains adhered to the skin during surgery as intended, while not being so strongly adhesive that it causes skin irritation on removal.
A detailed description of the peel tester is available with the online version of this article as a data supplement at jbjs.org.
Note: Assistance with drafting and revision of this manuscript was provided by Leslie Charles, MS, GreenTree Medical Writing, LLC.
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