Hello, and welcome to Surgical Wound Care, Myth vs. Reality. I think this is a fascinating topic. Though I've entitled this as a point-counterpoint type of talk, it's really an exploration into the history of wound care and how we got to where we are today from where we were 60 years ago. My name is Dan Eisen. I'm a professor at UC Davis. I've been here about 20 years. I have no relevant conflicts to disclose. The first wound care topic that we'll be exploring is the use of antibacterial ointments. So it's well thought that topical antibiotics do not prevent surgical site infections but they cause allergic contact dermatitis. So we're going to go look at the literature regarding this and see what's true. A little background on this topic. In the past, most assumed that the use of topical antibiotics would reduce chances of infection. It makes sense, right? Topical antibiotics, they act locally. They're less likely to have systemic issues such as diarrhea, drug reactions, less likely to cause resistance. In the 90s, an RCT was published in JAMA demonstrating no efficacy. Numerous case reports exist detailing the incidence of allergic contact dermatitis using topical antibiotics. So that's kind of where this whole don't use topical antibiotics philosophy came from. So here's the original study that I was just mentioning that changed people's minds about the standard use of topical antibiotics. It was a double-blind, randomized study looking at dermatologic procedures. Those procedures included shave biopsies, punch biopsies, scrape and burn procedures, mows, excisions, and dermabrasions. So relatively heterogeneous group of things there. Most wounds were on the face and trunk. About 75% of procedures were either shave biopsies or punch biopsies. So that helps us kind of understand the background of what these people were looking at, right? Here's the results of that study. You can see here that there are actually more infections in the petrolotum group than there were in the abacitracin group. But the difference was not statistically significant. You can also see that 0.9% of those in the abacitracin group developed allergic contact dermatitis, which was proven by patch testing. This difference was not significant also from the petrolotum group, but the p-value was 0.12, which many would consider a statistical trend. My take-home message from the study is that even if the difference in surgical site infections was significant, let's say you had more participants in the study and you were able to show that, I still wouldn't prefer the intervention since it appears you get more gram-negative infections such as pseudomonas than in the petrolotum group where they're mostly gram-positives. And of course, we all know that pseudomonas has only one oral antibiotic or one class of antibiotics you can take orally to treat it, and that would be the fluoroquinolones, cipro, floxacin, or levofloxacin. And that class of antibiotics is not great. Premature tendon rupture can occur, sensory neural hearing loss. I've had quite a few patients develop tendinitis and pain in their tendons, and I almost never use that antibiotic. So I think avoiding this particular intervention, topical antibiotics, is a good way to go. Of course, there's other studies looking at the efficacy of topical antibiotics as well. Looking at kind of a summary of them, there was a Cochrane systematic review that was published in 2016 that reviewed all of them. This systematic review included eight studies comparing topical antibiotics to no topical antibiotics in 5,427 participants. The authors concluded that topical antibiotics probably reduce surgical site infections with a calculated number needed to treat, to prevent one infection, 50. So you need to administer the intervention to 50 people to prevent one infection. A more recent systematic review was published in 2023. Their study included two newer publications. And they found that topical antibiotics are superior to antiseptics and ointment. So is it time to go back to antibiotic ointments? Before we jump on the antibiotic bandwagon again, I think it's important to acknowledge the limitations in these systematic reviews. You know, the devil's always in the details. How good are your studies and what are you basing your conclusions on? So five of the 12 studies that were examined had less than 200 patients, which is woefully underpowered to detect a meaningful difference in infection rate. And also, the smaller study numbers tend to be much more susceptible to bias, basically erroneous findings. The studies also used nine different topical antibiotics and basically they grouped them all together thinking that they're all the same. But obviously, you know, different medications have different effects. Also, the types of wounds that they studied were quite heterogeneous. There were three RCTs that looked at the use of antibiotic ointments in skin cancer surgery, three that looked at skin lacerations and soft tissue injury, two that looked at the use of topical antibiotics for circumcisions, and one each for C-sections, appendectomy, hip replacement, umbilical laparoscopy, hand surgery, cardiac device implementation. Also, the surgical settings were quite different. There were six minor procedures, such as an emergency department, eight in the OR. There were also, as mentioned before, different medications. There was four that looked at neomycin, basotracin, polymyxin, two that looked at chloramphenicol, one at neomycin, two at basotracin, two at rifamycin, and two at muparicin, two at sulfamycin, and one for acetic acid. So quite different. What about allergic contact dermatitis? There were four trials that reported outcomes of that. Three trials reported at least one subject that developed it. One study reported no incidence at all. So what are the conclusions? Evidence is inconclusive that topical antibiotics reduce infection rate, at least in my opinion. Allergic contact dermatitis has been reported in small numbers in some RCTs. Okay, moving on to our next myth. That's that wounds heal faster when you expose them to air. I'm sure you've had lots of patients that say that's how they like to heal, and that's the way they're going to do it. People have been healing via scab formation since the birth of humanity, so I don't know, probably at least 200,000 years or so. And that was thought to be totally fine up until the 1960s when Winter published this study in Nature. And what he did is he wounded two pigs, and he let some wounds heal by second intent, and he let other wounds heal with a polyethylene film over them to keep them occluded so they didn't dry out. So he found that there was only about 50% as much re-epithelialization at day three in air-exposed wounds as in film-covered wounds. And that was significantly different. You may ask yourself, well, why would there be any difference at all? And that's exactly what he was thinking. So he did some histologic studies, and he found that keratinocytes have to migrate beneath the scab to reach the injured site. And also, that part of the damaged dermis is incorporated in the scab. So that gets removed, and that has to be reconstituted. Whereas in an occluded wound, the keratinocytes don't have any scab to migrate through. They can just cruise where they need to go. And it doesn't have to reconstitute the dermis that's incorporated in the scab and gets destroyed. So things can heal faster. You may say to yourself, well, that's in pigs. Clearly humans are different from pigs. So in order to answer the question of whether humans heal faster with occluded wounds than they do by scab formation, Maybach and Hinman did this study looking at wounds in human volunteers. And what they found was that wounds healed faster with occlusion than ear-dried, just like in pigs. Now it should be noted that even though wounds healed faster at day three with occlusion, both arms of the study, meaning occluded wounds and open ear wounds, were the same by day seven. So for me, the take-home message is, yeah, wounds do heal faster with occlusion, but if your patient neglects their wound care and heals with a scab, well, it's no big deal. You're probably back to baseline by day seven, right? The next wound care issue we'll be addressing is the use of occlusive dressings. Many believe that these increase the chances of infection. When talking about post-operative wound care, it's useful to review the history just to put things in context. We have records that date back at least 4,000 years regarding wound care. Initially, small wounds typically were closed with stitches to aid in healing, and bigger ones were packed with lint. And typically those were covered with either grease or oil, and of course that made it non-stick, and it also prevented rotting, which is a good thing. With time, surgeons found that the use of honey, wine, vinegar, metallic salts helped prevent infection. This was all prior to the advent of germ therapy in the late 1800s. As with most things, pretty much everything changes with time. Before the 1960s, it was thought it was best to let wounds dry out. Dressings were not much different from the 60s and from the past thousands of years, and they consisted mostly of non-included cotton or wool. But that approach changed after the 1962 winter publication. As technological innovations became more prevalent, new dressings became available, including polyurethane membrane dressings. These dressings are transparent and allow visualization of the wound, unlike traditional gauze dressings. In 1983, there was a comparison study looking at polyurethane membrane dressings to conventional gauze dressings in 50 patients. This study included a variety of different procedures. At the end of the study, more patients in the polyurethane membrane group had absence of complications with fewer infections. This study clearly had its limitations, mostly the heterogeneity of the procedures studied and a small subject number, but at least there were no alarms regarding infection with occlusive dressing use. In 1988, a study more relevant to dermatology was published on the use of transparent film dressings in Mohs surgery. This study was randomized and contained 58 participants, and they studied transparent film compared to dry gauze with polysporin ointment. During the first week of treatment, the wound surface contracted on average 3% in the film dressing group versus 1% in the gauze dressing with ointment group, which was statistically significant. At week two, the transparent film dressing contracted numerically but not statistically faster. They were statistically similar in terms of contraction for the rest of the study. The transparent film group also re-epithelialized significantly more at weeks two and three than the gauze and ointment group. Also of significance, there were no infections that were recorded. The median number of days to healing was 20 in the transparent film dressing group and 26 in the gauze dressing ointment group. Overall, the transparent film dressing group healed faster than the gauze ointment group did, as measured by wound contraction, re-epithelialized faster, and also very significantly, the transparent film group had significantly less pain. When looking at other outcomes, only 5 of 20 patients in the transparent film dressing group had a mild deformity, while 14 of 25 in the gauze dressing ointment group had a mild to marked deformity. Forty-six percent of patients in the transparent group state that the scar had improved after six months, and 62% rated the cosmetic appearance as excellent. In contrast, only 0% and 20% respectively stated the same in the gauze dressing ointment group. Those differences were statistically significant. The median global score was 15 for patients in the transparent film dressing group and only 12 for those in the gauze dressing ointment group, with higher scores being better. This study looked at the temporal relationship to wounding and dressing application. Intradermal wounds were created in pigs with an electric dermatome. There were two components to the study. Early removal of the dressing, removed at 6, 24, and 48 hours, and delayed application of the dressing, which was at 0, 2, 6, and 24 hours. The figure on the left shows that the longer occlusion results in faster re-epithelialization. The one on the right shows that immediate application of dressing after wounding is superior to delayed application. By day four, most arms were similar in terms of delayed application, and even exposed areas not significantly different. Multiple studies have confirmed the finding that occlusive dressings heal with less pain than gauze with antibiotic ointments. The study shown here showed no difference between the use of hydrocolloid dressings and polyurethane film. This 1991 study looked at the healing speed in pain with occlusive dressings. The occlusive dressing site healed 3.8 times faster than conventional therapy, and pain was six times less likely and three times shorter in the occluded site. So now that we know occlusive dressing allows for faster healing with less pain, is applying ointment underneath them necessary? This 2006 study was an RCT with three arms. Occlusive dressing plus no ointment, paraffin ointment, or mupiricin ointment. Complications were evaluated at suture removal. Patients were surveyed six to nine months later. 926 patients were screened for inclusion. 778 patients with 1,801 wounds entered the study. 72.9% returned the survey. Most wounds were excisions, 69% of which were them, 30% were flaps, and 1% were grafts. Interestingly, the wound complication rate was highest in the mupiricin arm at 4.8%, and lowest in the no ointment group at 3.5%. This was not statistically significant. There was no allergic contact dermatitis due to the ointments. Scar complications were also highest in the mupiricin arm, 1.2%, which were mostly skin necrosis, and lowest in the no ointment arm, 0%. The difference was statistically significant. There appears to be no benefit to ointment or topical antibiotics beneath the occlusive dressing. No significant differences were reported by patients in terms of pain or overall appearance. The study did not specify how long the original surgical dressing was left on, whether a pressure dressing was placed over the occlusive dressing, whether or when bathing was allowed, or other wound care instructions. This is a more recent study published in 2022 with 86 patients who had a prior history of conventional wound care and had their wounds covered with a hydrocolloid dressing. Participants were surveyed about preference for either conventional dressing versus hydrocolloid dressings. At the end of the study, it was found that patients who used hydrocolloid dressings had higher ratings for comfort, convenience, simplicity, and subjective scar appearance. This study looked at adherence to wound care regimens. The results indicate that most patients are adherent with wound care instructions. Those that are not adherent often have discomfort with wound care, are too busy, or feel well. This illustrates that it's important to choose a wound care regimen that is non-painful and non-time intensive. This is a network meta-analysis that was done comparing moist dressing after suturing. One can see that there are a few studies comparing gauze to occlusive dressings, most of which have small subject numbers. This is one study from that group that was published in 2015. There are broad different types of procedure studies, so a lot of heterogeneity. You can see that things ranged anywhere from orthopedic surgery to gynecology. For results, we found that there was a 1.4% surgical site infection in the polyurethane film arm versus a 6.6% in the gauze tape arm, which was highly significant. Similarly, there was less blisters and erythema in the polyurethane group. This was another small RCT comparing gauze to occlusive dressings. One patient developed a surgical site infection in the occlusive group versus 5 in the gauze group. There was not a significant difference to the small study size. This is another small study comparing gauze to occlusive dressings. There are no surgical site infections in either arm. At the four-week visit, both the patient and surgeon rated scar segments covered by the hydrochloric dressing better with respect to color, evenness, and suppleness. But by a seven-month follow-up, the differences were no longer significant. So what's the take-home message regarding occlusive dressings? Basically, we need better-powered, higher-quality studies to draw conclusions regarding surgical site infection and use of occlusive dressings. However, existing evidence is reassuring. Occlusive dressings do seem to be less painful than the use of gauze and more convenient for the patient to use. That is the end of this segment on surgical wound care. Hopefully you found the history regarding wound care and the information available as interesting as I did.

wound care

antibacterial ointments

occlusive dressings

healing speed

infection prevention

allergic contact dermatitis