Wound healing

In the last step Professor Finn Gottrup took us through wound management and its history. In this step we will go through the current understanding of wound healing and its phases, types, and factors involved in the process.

Generally, wound healing consists of the following four steps:

  • Haemostasis: vascular constriction, platelet aggregation, degranulation, and fibrin formation or thrombus.

  • Inflammation: neutrophil infiltration, monocyte infiltration, macrophage differentiation, and lymphocyte infiltration.

  • Proliferation: re-epithelialisation, angiogenesis, collagen synthesis, and extracellular matrix formation.

  • Remodeling: collagen remodeling, vascular maturation, and regression.

A simpler way of classifying wound healing is by the classic clinical phases:

  • Inflammation Phase (exudation): 2 - 4 Days.

  • Fibroplasia Phase (proliferation): 10 - 12 Days.

  • Maturation Phase (scar formation): > 1 Year.

The images below depict the inflammatory phase. The wound is red, painful, and produces exudate.

swollen and red wound Click to enlarge

Because of this phase, surgical wounds show oedema (30% increase in all dimensions of the tissue). If a wound is sutured too tight, ischaemia can occur as well. Below, you can see a diagrammatic representation of a nail embedded in skin and the consequences of this, as well as an image of the skin after the nail has been removed. You can see the swelling in the wound region as well.

diagramatic representation of oedema and an image of oedema in a wound. Click to enlarge

Types of wound healing:

The regeneration and repair of wounds. Click to enlarge

Regeneration

Image showing when regeneration of a wound occurs: after erosion and blistering. Click to enlarge

Erosion and blisters require regeneration to heal. The tissue lost is replaced by the same type of tissue.

Using the principle of regeneration, split skin transplantation and bone repair procedures are carried out.

Split skin transplantation and the healing of a wound. Click to enlarge

Repair

Image showing how repair occurs in wounds. Click to enlarge

In repair, scars are formed, and these may be of various different types (as seen above). The tissue lost is replaced by new (scar) tissue.

Factors of importance for wound healing/infection:

Image showing the various factors of importance for wound healing including patient-related factors and technical-surgical factors Click to enlarge

After reading this section, try to answer the following questions in the comments section below.

  1. How do you detect the inflammatory phase of a wound? What are the signs observed?

  2. In you opinion, which is the most important patient factor and techno-surgical factor contributing to wound healing? Why do you think this?

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This article is from the free online course:

Antimicrobial Stewardship in Wound Management

BSAC

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