Wound healing in chronic and hard-to-heal cases

Despite advances in dressing technology and best practice, wound care is in crisis: the number of hard-to-heal wounds is increasing¹. Patients can suffer from severe pain and inflammation can also occur. Successful treatment requires an accurate diagnosis of the wound condition, knowledge of the course of secondary wound healing, as well as patience and experience. 

Primary and Secondary Wound Healing: What's the Difference?

Anyone who deals with this professionally knows the difference between primary wound healing and secondary wound healing: Wounds healing by primary intention, for example surgical incisions where the edges of the skin are approximated and closed with sutures, glue or staples, immediately following surgery. There is usually little tissue loss and after ten days the skin is restored.

Secondary wound healing occurs when a lot of tissue has been lost, for example in deep flesh wounds with gaping edges, as well as in chronic or inflamed wounds with impaired wound healing. The body replaces the tissue with granulation tissue and a larger scar is created, which matures for up to 12 months.

The wound healing phases are the same for both types of wounds, but secondary wound healing is often challenging. This is especially true when patients are cared for in the first contact: It is not uncommon for them to live with chronic wounds for months or years. The healing process requires sensitivity and experience. Wound Hygiene should be performed at each stage of a hard-to-heal wound until it has fully healed².

How do the three wound healing phases work?

1. Exudation phase is the first phase of wound healing. Fluid, known as exudate is produced so that cell debris, bacteria and other foreign bodies are flushed out of the wound. The high exudation is a sign of the body's cleansing and defense performance. Typical signs of inflammation such as redness, swelling, pain, functional impairment and overheating occur. In addition, regrowth begins during the exudation phase, which is essential for wound healing. The volume of exudate production should be a key consideration, as excess exudate levels can encourage the spread of biofilm, and impair cell proliferation and wound healing¹.
   
   Suitable wound dressings, such as ConvaFoam™ can help to keep the wound germ-free.
   
   In the case of acute wounds, this cleaning phase is usually completed after two to three days. Chronic wounds usually have a much longer duration of the exudation phase, as the cleaning process can stagnate here.
2. Granulation phase: here the body fills the gap in the tissue, the exudate decreases significantly. In this phase, the wound must not dry out as moist wound environment supports the healing of both acute and chronic wounds, promoting the growth of new tissue³. The wound is clean, the fresh tissue appears deep red in color, well supplied with blood. In acute wounds, the granulation phase begins from the second day at the earliest and can last up to 14 days. Since the new capillaries are extremely sensitive, the focus of the treatment is on long, undisturbed wound rest. Dressings should not stick to the wound base during this phase and should be able to be removed with causing trauma to the wound bed. 
3. Epithelisation phase: The third wound healing phase is the epithelialisation phase, also known as the repair or regeneration phase. Granulation cells are degraded, skin and tissue shrink, and the scar develops. The cell layer also thickens until a complete wound closure occurs. The epithelial tissue appears pink to light pink and exudation decreases sharply. If this phase is not completed after around eight weeks, the wound is considered chronic or hard-to-heal. In order not to injure the fresh epithelial tissue, bandages should still not stick to the wound base. 
   
   As with the granulation phase, the focus is on long, undisturbed wound rest and an ideal moist, warm wound healing environment.

It is characteristic of hard-to-heal or stagnant wounds that each healing stage can be delayed. This means the wound may become infected in the first phase, the granulation phase may be disturbed or the wound may not close. The last stage of the epithelialisation phase, in which the scar is supposed to mature, is often completely absent in chronic wounds due to recurrence.

What interferes with wound healing?

Infections, constant rubbing or pressure from lying on the injured area interfere with healing. A lack of blood circulation and too little oxygen can also hinder the wound heaing process. The wound healing phases then take much longer. Biofilms such as bacteria or fungi are also a common cause of wound healing disorders. They colonise the wound on the surface and form a colony. 

Which wound dressing for which wound?

Skin and tissue need the right environment to heal: the combination of moisture, warmth and low germs is ideal. Wound care products should be individually adapted to the condition of the wound and the needs of the patient. Three check questions will help:

• What is the phase of wound healing?
• How much exudate is there?
• Is the wound inflamed or covered with biofilm?

References

1. Murphy 2020 Journal of Wound Care International Consensus- Defying hard-to-heal wounds with an early antibiofilm intervention strategy: wound hygiene

2. Murphy 2022 International Consensus Document. Embedding Wound Hygiene into a proactive wound healing strategy

3. Okan et al 2007 The role of moisture balance in wound healing