February 1, 2012
We've all winced with pain, had our eyes well up, and maybe even inadvertently ripped body hair from the roots while removing an aggressive bandage or surgical tape from our skin. The experience is unpleasant, to say the least. But for patients with delicate skin or serious wounds, aggressive adhesives can exacerbate existing wounds, create new wounds, and delay healing in addition to causing pain. As these sensitive-skinned patients continue to grow in number owing to rising instances of Type 2 diabetes and an ample aging population, manufacturers of wound-care products are increasingly turning to suppliers for skin-friendly, low-trauma adhesive options.
Protecting Patients' Skin
Skin-friendly silicone adhesives from Dow Corning are optically clear and provide gentle adhesion as well as easy, painless removal from the skin.
Although skin-friendly adhesives have been on the market for decades, they have experienced a surge in popularity in recent years as target patient populations for the products have swelled dramatically and pain management has moved to the forefront of patient care. "Some [adhesives on the market] require pain medication for patients when removing dressings because it's so painful and the adhesive is so aggressive," notes Jeff Purnell, R&D group leader, Adhesives Research Inc. (Glen Rock, PA). "In the wound-care industry, obviously you're dealing with damaged skin that this adhesive is bonding to. So, it's always a desire to have less-painful release of the adhesive from the skin of the patient."
While mitigating the pain and trauma associated with dressing removal is beneficial to all patients, these adhesive attributes are particularly desirable for treating patients with sensitive or delicate skin. Because of their naturally thinner skin, elderly patients, for example, are vulnerable to skin tears, or epidermal stripping, resulting from the removal of an aggressive or substandard dressing, according to Brian Davies, vice president of sales at Brady Medical (Mesquite, TX). Consequently, patients will have a new wound that requires treatment in addition to the original wound.
Likewise, aggressive dressings can exacerbate existing wounds in patients suffering from conditions such as diabetes. "Diabetes can lead to serious ulcers and chronic wound conditions that really require low-trauma and skin-friendly adhesive products," observes James Stephenson, global market manager, Dow Corning Healthcare (Midland, MI). "Very aggressive adhesives can cause a lot of trauma [during removal] to the wound bed as well as to the surrounding areas that are already struggling to heal, in most cases." Low-trauma dressings, Stephenson adds, are optimized to prevent adhesion of the dressing to such delicate wound beds, minimizing the potential for further damage to the site.
Building on a solid foundation in a variety of healthcare applications, silicones are often considered the material of choice for use in skin-friendly adhesives. "Hydrocolloids can bond up if they're not saturated and turn into a gel-like substance. They can also rip the skin if the wound is not wet enough," Davies says. "But silicone is low trauma from the moment you stick it on."
Lacking a reinforcing silica filler, low-trauma silicone adhesives have the consistency of a tacky, gel-like substance, providing for gentle skin adhesion in combination with silicone's well-known biocompatibility. "The biocompatible nature of silicones makes them an ideal material for low-trauma wound dressings," Stephenson comments. "In chronic wound applications where there is potential for contact with broken or compromised skin, biocompatibility is extremely important."
The by-product of a platinum-catalyzed reaction, Dow Corning's low-density, cross-linked, silicone-elastomer soft-skin adhesives (SSAs) do not strip skin, Stephenson adds. They adhere to skin in response to light pressure; however, low peel or shear forces allow for clean, immediate debonding of the silicone adhesive from the skin upon removal. Substrates can include high- and low-density polyethylene, as well as polyester and silicone release liners.
"It's the control of the material's long siloxane polymer chain that lends itself to good wetting and low--but extensive--skin interaction at the same time," Stephenson says. "That's the unique combination you're looking for in SSAs: Low interaction with human skin leads to no skin stripping, hence, lower trauma and less pain."
Low-trauma silicone adhesives are also a specialty area for Brady Medical, which custom manufactures silicone adhesives and finished sterile dressings for private-label customers. "We obtain our silicone solution from Bluestar Silicones (East Brunswick, NJ) and tailor the level of aggressiveness for the adhesive," Davies explains. "Then, we cast the silicone through our coating process and back it with a nonwoven or breathable film and turn it into a dressing or securement tape." Dressings are suited for use for up to seven days.
Atraumatic Nonsilicone Adhesives
Straying from the silicone status quo for skin-friendly adhesives, on the other hand, is Adhesives Research. The company has developed a nonsilicone adhesive platform that boasts residue-free removal, secure repositioning, and a pain index rating of less than 2.5 on the Wong-Baker FACES pain rating scale. In contrast, a standard skin-friendly adhesive has a pain index rating of 4 to 5, based on internal studies.
Providing firm but gentle adhesion, the nonsilicone adhesive offers what the company claims are performance characteristics comparable with those of silicone while overcoming some of the material's drawbacks. The pressure-sensitive adhesive (PSA) technology enables the design of thinner adhesives than is possible with silicones, for instance. In order to ensure a secure bond with the skin, silicone adhesives often require a minimum thickness of 80 µm, according to the company. "To get the same bond properties with silicone adhesives that we have with our low-trauma adhesives, however, you would typically have a much thicker adhesive," Purnell explains. "And it is much more costly to create the thicker adhesive."
In addition to being more costly, thicker low-trauma silicone adhesives have a greater chance than their thinner nonsilicone counterparts to experience edge lifting, according to Gozde Karabiyik, a product development chemist at Adhesives Research. She notes that thicker adhesives generate more friction, which can cause the lifted edge to "grab" clothing or sheets, for example, as the patient moves.
Consequently, the bandage may be accidentally pulled off of the patient, exposing the wound and requiring a new dressing.
Another advantage of the nonsilicone adhesive platform, the company states, is its ability to withstand gamma sterilization. "To gamma sterilize a silicone adhesive and maintain the same properties is not easy to do," Purnell notes. Gamma sterilization of silicone adhesives can compromise bond levels and, in turn, adhesion of the dressing to the skin. Silicone adhesives can successfully undergo ethylene oxide (EtO) sterilization, however.
And while the ability to withstand gamma sterilization, the low cost, and the thinner profile are all benefits of the low-trauma nonsilicone adhesive, the primary advantage of the technology, according to Purnell, is that it is customizable. "We can customize the adhesive to be more or less aggressive, depending on the application, which gives it a lot more flexibility," he says.
Optimized for a wear time of one to three days, the adhesive can be converted into a patch or dressing on a variety of substrates, including polyurethanes and nonwovens. "We can tailor the wear time, level of breathability, pain level, adhesion level, thickness, and the substrate," Karabiyik says. "We can customize our adhesive formulation and tape construction to meet any unique design criteria that a customer has."
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