Chronic Wounds

What is a Chronic Wound?

Commonly referred to as 'non - healing' wounds.

A chronic wound may be defined as one that is physiologically impaired due to a disruption of the wound healing cycle as a result of impaired angiogenesis, innervation, or cellular migration, among other reasons. It does not follow the process of normal wound healing .

How long does it take to heal?

The precise timeline for complete epithelialization varies depending on numerous factors, including comorbidities (eg, diabetes, autoimmune disease, peripheral artery disease), increased body mass index, anatomic location, and medications. However, regardless of etiology, wound healing normally progresses at a sustained, measureable rate. Although there is no specific time frame that clearly differentiates an acute from a chronic wound, some suggest that the lack of approximately 15 percent reduction weekly or approximately 50 percent reduction of the surface area of the wound over a one-month period indicates a chronic state .

Types of Chronic Wounds

Traumatic wound
Surgical wound
Venous ulcer
Arterial ulcer
Chronic ulcer
Pressure ulcer
Diabetic foot ulcer
Flap or graft

Healing Process -

Wound healing occurs in stages in an organized way following four processes:

Hemostasis

Inflammation

Proliferation
Maturation

Hemostasis

This is the process of the wound being closed by clotting. Hemostasis starts when blood leaks out of the body. The first step of hemostasis is when blood vessels constrict to restrict the blood flow. Next, platelets stick together in order to seal the break in the wall of the blood vessel. Finally, coagulation occurs and reinforces the platelet plug with threads of fibrin which are like a molecular binding agent. The hemostasis stage of wound healing happens very quickly. The platelets adhere to the sub-endothelium surface within seconds of the rupture of a blood vessel's epithelial wall. After that, the first fibrin strands begin to adhere in about sixty seconds. As the fibrin mesh begins, the blood is transformed from liquid to gel through pro-coagulants and the release of prothrombin. The formation of a thrombus or clot keeps the platelets and blood cells trapped in the wound area. The thrombus is generally important in the stages of wound healing but becomes a problem if it detaches from the vessel wall and goes through the circulatory system, possibly causing a stroke, pulmonary embolism or heart attack.

Inflammation

This is the second stage of wound healing and begins right after the injury when the injured blood vessels leak transudate (made of water, salt, and protein) causing localized swelling. Inflammation both controls bleeding and prevents infection. The fluid engorgement allows healing and repair cells to move to the site of the wound. During the inflammatory phase, damaged cells, pathogens, and bacteria are removed from the wound area. These white blood cells, growth factors, nutrients and enzymes create the swelling, heat, pain and redness commonly seen during this stage of wound healing. Inflammation is a natural part of the wound healing process and only problematic if prolonged or excessive.

Proliferation

This phase of wound healing is when the wound is rebuilt with new tissue made up of collagen and extracellular matrix. In the proliferative phase, the wound contracts as new tissues are built. In addition, a new network of blood vessels must be constructed so that the granulation tissue can be healthy and receive sufficient oxygen and nutrients. Myofibroblasts cause the wound to contract by gripping the wound edges and pulling them together using a mechanism similar to that of smooth muscle cells. In healthy stages of wound healing, granulation tissue is pink or red and uneven in texture. Moreover, healthy granulation tissue does not bleed easily. Dark granulation tissue can be a sign of infection, ischemia, or poor perfusion. In the final phase of the proliferative stage of wound healing, epithelial cells resurface the injury. It is important to remember that epithelialization happens faster when wounds are kept moist and hydrated. Generally, when occlusive or semiocclusive dressings are applied within 48 hours after injury, they will maintain correct tissue humidity to optimize epithelialization.

Maturation

Also called the remodeling stage of wound healing, the maturation phase is when collagen is remodeled from type III to type I and the wound fully closes. The cells that had been used to repair the wound but which are no longer needed are removed by apoptosis, or programmed cell death. When collagen is laid down during the proliferative phase, it is disorganized and the wound is thick. During the maturation phase, collagen is aligned along tension lines and water is reabsorbed so the collagen fibers can lie closer together and cross-link. Cross-linking of collagen reduces scar thickness and also makes the skin area of the wound stronger. Generally, remodeling begins about 21 days after an injury and can continue for a year or more. Even with cross-linking, healed wound areas continue to be weaker than uninjured skin, generally only having 80% of the tensile strength of unwounded skin.

Treatment protocol

Cleaning the wound

wound debridement (the removal of dead or infected skin),

therapy to improve circulation,

compression wraps,

Advanced wound dressings,

skin and tissue grafting,

negative pressure wound therapy,

application of topical growth factors.