Addressing the Pain: Atraumatic Dressings

   The ability to remove a dressing without causing trauma to the wound and surrounding skin or pain to the patient is an important feature in the performance of that product. Over the years, dressings with a variety of different types of wound contact layers have been developed that aim to reduce adherence to a drying wound. This article discusses the causes of traumatic injuries associated with the removal of dressings and proposes that the term atraumatic dressings be adopted to describe products that do not cause such problems in clinical practice.

   When Winter published his seminal paper on the effect of occlusion on the rate of epithelialization of superficial wounds in the young domestic pig,¹ he began a new chapter in the understanding of the mechanisms by which wounds heal and the impact of dressings on the process. Based on the results of this and later work, he identified a number of criteria he believed characterized a good surgical dressing.² Although Winter was referring to the properties of a single dressing, the performance criteria are equally applicable to a dressing system that comprises a primary wound contact layer, some form of secondary absorbent layer, and an appropriate retention layer. Key aspects of dressing performance as described by Winter relate to damage to the healing wound and surrounding skin. Once adherence has occurred, dressing removal can be painful and may cause damage to the fragile, newly formed epithelium, leading to extended healing times and increased risk of scar formation.

   Separating the functions of the primary wound contact layer from those of the secondary absorbent layer has significant, practical advantages, as this provides the clinician with a degree of flexibility when selecting or constructing a dressing system for a particular wound at a given stage in the healing cycle. The important contribution made by the secondary dressing is often overlooked during this selection process but can be vital in determining the success (or otherwise) of a particular treatment, especially when using products such as hydrogels or alginate sheets.³

   In recognizing the limitations of gauze, some manufacturers have developed new types of wound contact materials that may be used as "stand alone" dressings or as facing layers for absorbent dressing pads. These include perforated or vacuum-ruptured plastic films, foams, finely woven nylon mesh, heat-calendered non-woven fabrics made from hydrophobic fibers, silicone-coated knitted fabrics, and a non-woven material coated with metallic aluminum. Such dressings have been described by their manufacturers and others as non-adherent, or more accurately low-adherent. The structure and use of many of these low-adherent materials have been reviewed previously.⁴

Mechanics of Adherence

   According to Winter, the main cause of adherence of dressings to wounds is "the mechanical key formed by proteinaceous exudate, which on drying becomes a good glue." He also recognized a secondary mechanism of adherence where new tissue grows into the structure of the dressing and subsequently incorporates some of the components into the healing wound.
Using a pig model, Winter examined the performance of a commonly used perforated plastic film dressing. After several days, the film became attached to the wound as columns of exudate connecting the dressing to the wound surface dried out. Histological studies showed that after extended use, regular patches of damage were visible on areas corresponding to the perforations, although the epidermis immediately beneath the plastic film remained intact. Winters' view was that as new epidermis "floats on the wound surface" in the first week or so, it can be damaged from removing a lightly adherent dressing as easily as one that is firmly stuck. He concluded, "the actual adherence is not particularly relevant; it is an all-or-nothing phenomenon."

   This observation calls into question the value of the term low-adherent, as this is commonly understood to describe the force required to remove the dressing rather than to quantify the degree of damage caused by its removal. Although some correlation between the two parameters may exist, this may not be as reliable as is generally assumed.
Irrespective of the nature of the wound contact layer, most dressings also require the use of a bandage with some form of adhesive layer to keep them in position. This adhesive layer may be separate or be an integral part of the product itself, forming an island dressing in which the low-adherent pad is located centrally on the sheet of plastic, foam, fabric, coated with adhesive. While this area does not come in contact with the wound and, therefore, cannot cause damage to the newly formed tissue, repeatedly removing and replacing such dressings can damage surrounding skin, especially if the patient is elderly or the skin is particularly fragile.

   A number of surveys have been conducted in recent years to identify practitioners' views on wound-related pain and trauma. The first was a postal survey conducted in the UK where questionnaires were sent to 1,000 nurses, 373 of whom responded.⁵ The results indicated that although prevention of pain/trauma is considered by the majority of practitioners to be their principal consideration when changing dressings, no consensus about the types of products that best overcome these problems was reached. Of particular concern was the fact that 39% of those who responded were not aware of any products specifically designed to overcome problems of adherence, while the remaining approximately 60% identified no less than 28 dressings, most of which were not claimed by their manufacturers to possess such properties. The reason for the confusion is not clear, but it may be due in part to the somewhat non-specific and poorly defined nature of the term low-adherent and a failure to appreciate the performance characteristics of many of the dressings in current use.

   Findings from this survey prompted a larger international survey,⁶ where questionnaires were sent to 14,657 practitioners in 11 countries including the UK. The results of the 3,918 completed and returned questionnaires (27% return rate) indicated general agreement with the first survey - pain and trauma were ranked as the most important factors to consider when changing a dressing. Pain was most commonly associated with dressing changes and was related to dressings drying out or adhering to the wound bed - factors that also were considered to be responsible for wound trauma. Perhaps not surprisingly, pain-free removal and non-adherence were considered to be the most important characteristics of a dressing, and products such as hydrogels, gel-forming fibers, and those made of soft silicone were generally highly rated in this regard.

   In terms of their ability to prevent pain and trauma, dressings fall broadly into three categories as shown below, although the value of these definitions is somewhat limited, as adherence of a dressing to a wound can be influenced by many different factors.

   Adherent. This category of dressings includes those most practitioners consider likely to adhere to any type of drying wound. Examples include simple dressing pads or cotton gauze.

   Low-adherent. These products have a wound-contact surface designed specifically to reduce adherence and include some absorbent wound dressings and other products previously described.

   Non-adherent. Non-adherent dressings maintain a moist gel layer over the wound and include hydrocolloids, hydrogels, and alginates. These would not be expected to adhere provided they are not allowed to dry out. The performance of some of these materials will largely be determined by the choice of a secondary dressing where this is required.

   It is important to recognize that this simple classification only relates to the interaction that takes place between the dressing and the wound itself; it takes no account of possible trauma caused to the surrounding skin by removal of the adhesive products such as hydrocolloids, adhesive films, and self-adhesive foams. It is proposed that a new term, atraumatic dressings, be adopted to take these factors into account and more accurately define products which, on removal, do not cause trauma either to newly formed tissue or to the periwound skin.

   Recently, a category of dressings was introduced that claims to overcome the twin problems of adherence to the wound and damage to the surrounding skin. These dressings rely on an adhesive technology involving the use of soft silicone, a material that adheres readily to intact skin but does not stick to the surface of a moist wound and does not cause damage when removed.⁷ The results of a review of the current literature (available in the original article) suggest that dressings coated with soft silicone appear to meet this requirement - that the dressings comply with the definition of atraumatic. Continuing research will determine further the effectiveness and efficacy of such dressings.

   Addressing the Pain is made possible through the support of Mölnlycke Health Care, Newtown, Pa.

1. Winter GD. Formation of the scab and rate of epithelialization of superficial wounds in the skin of the young domestic pig. Nature. 1962;193:293–294.

2. Winter GD. Methods for the biological evaluation of dressings. In: Turner TD, Brain KR (eds). Surgical Dressings in the Hospital Environment. Cardiff, UK: Surgical Dressings Research Unit, UWIST;1975:47–81.

3. Thomas S. The importance of secondary dressings in wound care. Journal of Wound Care. 1998;7(4):189–192.

4. Thomas S. Low-adherence dressings. Journal of Wound Care. 1994;3(1):27-30.

5. Hollinworth H, Collier M. Nurses' views about pain and trauma at dressing changes: results of a national survey. Journal of Wound Care. 2000;9(8):369–373.

6. Moffat CJ, Franks P, Hollinworth H. Understanding wound pain and trauma: an international perspective. In: EWMA Position Document: Pain at Wound Changes. London, UK: Medical Education Partnership;2002:2–7.

7. Dykes PJ, Heggie R, Hill SA. Effects of adhesive dressings on the stratum corneum of the skin. Journal of Wound Care. 2001;10(1):7–10.