**3. Stages of wound healing**

In general terms, the wound healing process can be divided into four stages with some potential overlap between the stages. Identification and recognition of the wound stage enables appropriate treatment objectives for that particular stage. When treating, practitioner at times may fail to establish correct treatment objectives due to failure to correctly recognise the healing stage of that particular wound.

### **3.1. Stage 1 (vascular response)**

reliable data are available for the cost of treating the wound which do not close with primary intention. A report by Lewis et al. [1] has carried out a comprehensive review of the literature and has found that the cost of dressings and other material alone could be as high as £37 million per year in England. Data for primary care are easily available as they purchase on Form 10 but the data for secondary care are difficult to find as most hospitals buy directly from manufacturers at specially negotiated price, therefore factoring this in is quite difficult and no reliable study has been found on literature search. If patient stays in hospital the cost of stay in hospital could be as high as £400–500 per day depending upon the geographic location of hospital. Additionally, the cost of staffing, local or general anaesthetic, has to be factored in as

Significant developments have taken place with regards to wound management over the course of the years. Thanks to the evolving technology, better understanding of the healing process and relevant contributing factors we are now able to address the problem in a timely, cost-effective and efficient manner. It is a developing area and therefore the means of man-

Understanding tissue healing is fundamental in wound management. Such a complex

Wound healing can be defined as the process by which the body restores and replaces function to damaged tissues [3]. Following tissue trauma, healing can be initiated through one of the

1. Regeneration, which means replacement of damaged tissue by an identical type of tissue. This process is only confined to a few types of cells, for example epithelial, liver and nerve cells

2. Repair, where damaged tissues are replaced by connective tissue to form a scar. This

In general terms, the wound healing process can be divided into four stages with some potential overlap between the stages. Identification and recognition of the wound stage enables appropriate treatment objectives for that particular stage. When treating, practitioner at times may fail to establish correct treatment objectives due to failure to correctly recognise the healing

physiological process is proven to be dependent on multiple inter-related factors [2].

well.

agement will only improve with time.

344 Wound Healing - New insights into Ancient Challenges

**2. Understanding tissue healing**

mechanism occurs in vast majority of cases [2].

**3. Stages of wound healing**

stage of that particular wound.

two mechanisms:

[2].

Tissue trauma leads to activation of coagulation cascade resulting in formation of a fibrin mesh to fill the gap within the tissue. It usually lasts up to 3 days [3].

**Scheme 1.** Stages of Wound healing.

### **3.2. Stage 2 (inflammatory response)**

At this stage, vasodilatation and increased permeability of the adjacent blood vessels are noted. This is the result of inflammatory mediators like histamine and prostaglandins released by mast cells. Clinically, this is characterised by redness, swelling, localised heat, pain and functional limitation. Clinical presentation at this stage might be confused with wound infection, as hyperaemia occurs in the first 3 weeks of healing.

Increased capillary permeability at this phase leads to exudates production containing essential growth factors, nutrients and enzymes mandatory for wound healing in addition to their anti-microbial characteristics [4].

Immuno-compromised patients might not be able to produce appropriate inflammatory response resulting in failure of activation of normal healing process [5].

### **3.3. Stage 3 (proliferative/granulation phase)**

New connective tissue starts to fill the wound and a decrease of the wound size is noted. This occurs as a result of epithelialisation, wound contraction and granulation [2]. Collagen and other extra-cellular materials form scaffolding on which the new capillaries grow (angiogenesis) to form connective tissue. The process is referred to as granulation formation [2]. Angiogenesis is promoted by material produced by macrophages including transforming growth factor (TGF) and tumour necrosis factor (TNF) [6].

Fibroblast contraction that takes place during this stage is responsible for wound contraction and hence reducing wound size. This is considered to be a crucial part of a large and open wound healing [7].


**Table 1.** Various growth factors involved in wound healing [10].

During the final phase of proliferation, re-epithelialisation takes place across the wound surface. This process will be delayed until the wound bed is filled with granulation tissue in cases of wound healing with secondary intention [2].
