How Should Clinical Wound Care and Management Translate to Effective Engineering Standard Testing Requirements from Foam Dressings? Mapping the Existing Gaps and Needs

Abstract

Significance: Wounds of all types remain one of the most important, expensive, and common medical problems, for example, up to approximately two-thirds of the work time of community nurses is spent on wound management. Many wounds are treated by means of dressings. The materials used in a dressing, their microarchitecture, and how they are composed and constructed form the basis for the laboratory and clinical performances of any advanced dressing. Recent Advances: The established structure/function principle in material science is reviewed and analyzed in this article in the context of wound dressings. This principle states that the microstructure determines the physical, mechanical, and fluid transport and handling properties, all of which are critically important for, and relevant to the, adequate performances of wound dressings. Critical Issues: According to the above principle, once the clinical requirements for wound care and management are defined for a given wound type and etiology, it should be theoretically possible to translate clinically relevant characteristics of dressings into physical test designs resulting specific metrics of materials, mechanical, and fluid transport and handling properties, all of which should be determined to meet the clinical objectives and be measurable through standardized bench testing. Future Directions: This multidisciplinary review article, written by an International Wound Dressing Technology Expert Panel, discusses the translation of clinical wound care and management into effective, basic engineering standard testing requirements from wound dressings with respect to material types, microarchitecture, and properties, to achieve the desirable performance in supporting healing and improving the quality of life of patients.

Keywords: exudate management; fluid handling and retention; laboratory testing methods and standards; test fluid; treatment.

Amit Gefen, PhD

Figure 1.

The established structure–function principle in material science is that the microstructure determines the properties, such as the mechanical and fluid handling characteristics (a). For wound dressings, “function” encompasses the mechanical, fluid transport, and retention properties (altogether). The focus of the vast majority of the existing testing standards for wound dressings is on the properties and function of the tested dressing products, not their structure or microstructure. In a multilayer foam dressing, for example, each layer of the dressing has its own set of the above properties, and accordingly, the “function” of the whole dressing structure is determined by the contribution of each of the material components, for example, to the effective permeability of the dressing structure (b).

Figure 2.

The fluid handling (or mass transport) performance of a certain wound dressing (as detailed in Table 1), which can be measured in a bioengineering laboratory setting, determines the likelihood of that dressing to successfully manage exudates, or alternatively, to fail in the more challenging clinical scenarios requiring, for example, the absorbency of high volume of exudation or of a viscous exudate; treatment of infected wounds; and protection of fragile periwound skin. Hence, the mass transport performance of the dressing eventually determines both the patient and the financial outcomes.

Figure 3.

A clinical documentation of the effect of an excessively stiff foam dressing on the periwound skin. The image shows the wound of a 67-year-old man with a history of obesity and chronic leg ulcers due to venous lymphedema. This patient developed a pretibial ulcer with moderate amount of drainage. A rectangular foam dressing with sharp corners (white arrow marking) was applied under a two-layer compression therapy system for at least five consecutive days. The deep indentation on the periwound skin, which was also associated with pain, is clearly visible. Of note, the dressing may not have been appropriately chosen by the clinician caring for this wound. The documentation of this case is courtesy of author K.W.

Figure 4.

Clinical documentations of dressing failures due to poor absorbency of viscous fluids in the care of acute and chronic wounds: (a) A highly exuding heel pressure ulcer where the polyurethane foam dressing had failed to absorb the viscous hematic exudate. The documentation of this case is courtesy of author PA. (b) A 60+ year-old male patient who underwent a left knee repair was at risk of postoperative bleeding. A conventional postoperative dressing was applied, but clearly failed (the images were taken at day 4 postsurgery), because the dressing needed to handle a relatively large amount of whole blood, which is considerably more viscous than plasma exudation. While appreciating that ideally, hemostasis of the wound should be achieved before applying a dressing, and therefore, bleeding into a dressing presents a considerable challenge for its fluid management and handling performance, in these two cases shown here, the absorption rate into the dressing was too slow and the rate of the incoming blood flow was too high, resulting in pooling of blood under the dressing (as opposed to the absorption and retention that a dressing is expected to achieve). The documentation of this case is courtesy of author TS. (c) An 82-year-old male patient with multiple venous leg ulcers on the same leg that release exudates with different viscosities. The dressing was clearly unable to absorb the more viscous exudate. The documentation of this case is courtesy of author P.A.