Wounds - Wound Healing

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Wounds - Wound Healing
Wounds - Wound Healing
Video: Wounds - Wound Healing
Video: Wounds and healing 6, Primary and secondary healing 2023, February

Wounds and wound healing

A wound is caused by damage to, destruction, or severing of the skin and the underlying tissue. Good wound healing is important in order to restore the protective function of the skin. The body can usually heal wounds by itself. The destroyed tissue is replaced by new tissue and scars can form. The larger and deeper a wound, the longer it takes for the wound to heal. The risk of complications, such as infection, is also higher with large wounds. When wound healing is disturbed, chronic wounds can develop.


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  • How can wounds arise?
  • How does normal wound healing work?
  • When do permanent scars appear?
  • What can interfere with wound healing?
  • How is wounds treated?

How can wounds arise?

Acute wounds are caused by sudden damage to the skin. Common causes are:

  • Injuries (traumas), e.g. grazes, bruises, cuts, stings, animal bites, burns, scalds, etc.,
  • medical interventions for diagnosis and treatment, e.g. biopsies, operations etc., or
  • Cosmetic measures that injure the skin, e.g. piercings, tattoos or cosmetic surgery.

Chronic wounds can arise from acute wounds when normal wound healing is disturbed.

The most common causes of chronic wounds are:

  • Circulatory disorder of a wound due to an existing illness (e.g. diabetes mellitus, intermittent claudication or venous disease),
  • long-term pressure on the skin, e.g. from lying down for a long time (decubitus)
  • Wound infection.

How does normal wound healing work?

The healing of a wound is a complex process and goes through several phases, some of which run simultaneously.

  • Immediately after an injury starts bleeding. The blood vessels in the wound narrow to reduce blood loss. The blood coagulates, ie it solidifies and fills the wound.
  • The protein fibrin is produced during blood clotting hemostasis. It glues the wound surface and protects the wound from pathogens. Moist fibrin is a yellow, transparent coating. Dried out fibrin forms a hard, yellowish plate. In addition, after the bleeding has stopped, inflammatory cells migrate into the wound. They clean the wound and protect it from infection. Bacteria and cell debris are washed out of the weeping wound in this phase by a wound fluid (exudate) and broken down. This phase of wound healing (cleaning or inflammation phase) takes about three days for normally healing acute wounds. In chronic wounds, wound healing is usually disturbed in this phase and the inflammation lasts longer. The exudate and fibrin form the wound crust (scab, scab) on the surface of the injury.
  • New tissue begins to form in the wound on the second day at the earliest. The first cells - so-called fibroblasts - migrate from the surrounding tissue and from the wound bed into the wound. Gradually new connective tissue (granulation tissue) is created. For the blood supply, tiny vessels (capillaries) grow into the new tissue from surrounding healthy blood vessels. In this phase the wound is well supplied with blood, dark red in color and shiny moist. The new granulation tissue with the new vessels is very sensitive. The wound should be treated, protected and spared with particular care. A warm, humid climate on the wound is ideal for healing. This phase (granulation or proliferation phase )can start on the second day and takes about two weeks with normal wound healing. With large wounds, it is more difficult for new cells to migrate than with small wounds or wounds with adjoining wound edges, and this phase takes longer.
  • In the final phase of wound healing, the granulation tissue turns into scar tissue. New epithelial cells migrate from the edge into the wound. The wound shrinks by about one to two millimeters per day until it is completely closed. This phase (regeneration or epithelialization phase) can begin on the fourth day and lasts about three weeks with normal wound healing until the wound closes. Even after the wound has closed, the resulting scar tissue changes due to the formation of new collagen. Scars can change over time, they become flatter, smaller, etc.

When do permanent scars appear?

Small wounds usually heal without permanent visible scars. In large wounds, scar tissue forms as the wound heals to replace the damaged tissue. With superficial wounds, such as abrasions, no or only small scars occur. Here the skin tissue can form (regenerate) fully functional. If deeper layers of the skin are also destroyed, the skin can no longer completely regenerate itself to its original state. Scar tissue forms instead of normal tissue. This is especially the case with very large wounds or when wound healing is impaired.

What can interfere with wound healing?

Various influences can disrupt normal wound healing. Then the wound heals poorly or stays open. In the case of poorly healing or chronic wounds, special medical treatment (wound management) is necessary.

The risk of poor wound healing and complications is increased with:

  • very large and deep wounds,
  • Foreign bodies in the wound, contamination of the wound,
  • an existing infection of the wound,
  • an unfavorable wound location, e.g. near a joint,
  • lack of wound rest or
  • lack of moisture in the wound.

Certain physical factors, existing illnesses or unhealthy lifestyle habits can also interfere with wound healing. They increase the risk of wound infections, including after an operation. These risk factors include:

  • old age,
  • Malnutrition,
  • Immobility,
  • poor immune status,
  • existing underlying diseases, e.g. diabetes mellitus, chronic venous insufficiency, intermittent claudication,
  • immunosuppressive therapies,
  • Obesity and
  • Smoke.

How is wounds treated?

In order for a wound to heal well and without complications, rapid, professional treatment and subsequent care until it has healed are important.

Smaller acute wounds or abrasions can be treated by laypeople themselves. It is important to clean the wound, for example with clean water or wound irrigation solution, and to cover it, for example with plasters or steristrips (wound suture strips). For more information, see Wound First Aid.

Rapid medical care is required for deep and large acute wounds. Treatment depends on the condition of the wound. A hospital stay may be necessary. The healing of chronic wounds also requires special medical treatment. For more information, see Wound Treatment.

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