Wounds - from physiology to wound dressing

Abstract

Introduction: Optimal wound management remains the subject of active research. Improved knowledge of physiological wound healing, systemic research into wound dressing and the evaluation of chemical disinfection have given rise to new approaches to wound care.

Methods: Selective literature review.

Results: The primary goals of wound management are rapid wound closure and a functional and aesthetically satisfactory scar. While basic treatment for primary wound healing is often simple, a number of problems can arise in chronic wounds, especially in elderly patients and those with multiple morbidity. It is therefore essential to maintain the basic conditions for physiological wound healing, in particular adequate wound moistness. Each dressing change should entail an evaluation of the wound status, careful cleansing, and treatment tailored to the phase of wound healing. Many therapeutic agents formerly in use are now obsolete. A variety of specific preparations are available for wound covering, including inert, interactive and bioactive substances. There remains a lack of good evidence for these, however.

Conclusions: New findings in molecular and cell biology have improved our understanding of physiological wound healing, and approach to wound care and dressing.

Keywords: chronic wounds; wound care; wound dressing; wound healing.

Figure 1

Early phase of wound healing (3^rd day). The defect is filled with a fibrin clot. The platelets involved activate neutrophil granulocytes, which remove foreign bodies or bacteria and stimulate the transformation of monocytes to macrophages. Macrophages play a central role in the early phase of wound healing, as they stimulate fibroblasts and vascular endothelium to form granulation tissue. All cellular interactions are controlled by cytokines (growth factors) (from [4]). VEGF, vascular endothelial growth factor; IGF, insulin-like growth factor; TGF, transforming growth factor; PDGFAB, platelet-derived growth factor AB/BB; KFG, keratinocyte growth factor; FGF, fibroblast growth factor

Figure 2

From the 3^rd to 7^th day immigration of fibroblasts and vascular proliferation occur with ingrowth of capillaries (proliferative phase). In the repair or regeneration phase, the matrix metalloproteinases (MMP 1, 2, 3, 13) then induce remodeling of the extracellular matrix into tearing-resistant collagen structures. Depending on the size of the wound, epithelization and scar formation occur. u-pA, urokinase plasminogen activator; t-PA, tissue plasminogen activator (from [4])

Figure 3

Figure 3: Wound healing: a) wound on the lateral side of the lower leg with extensive necroses and fibrin residues in an 82-year-old female patient (left caudal, right cranial). The state of the wound is a consequence of incorrect treatment (dry wound dressing). b) The wound was surgically debrided and covered with a moist dressing. Individual areas of granulation are forming (proliferative phase of wound healing). c) Continued moist dressings, continued granulation also beyond the tendon level (repair phase of wound healing). d) After placement of a secondary suture, a stable scar has formed. The care of the distal part of the wound could be improved.

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