Wound care / What we treat?

Description of the illness

The skin is a large sensory organ that interacts with the environment, and sends signals to the brain about touch, pain, vibration, and position.

There are two layers of skin that cover the body, the epidermis and dermis.

The epidermis is the outermost layer of skin, the part that can be seen, and is very active with new skin cells being formed and gradually being shed. There are different kinds of epidermal cells:

  • Keratinocytes are the main skin cells that we see. New epidermal cells begin where the epidermis and dermis meet. These cells gradually mature and rise to the surface of the skin and are eventually shed to be replaced by new ones. The epidermis has no blood vessels and receives nutrition from the underlying dermis.
  • Melanocytes contain pigment and provide coloration to the skin and are responsible for absorbing radiation and protecting against the damage caused by ultraviolet radiation.
  • Langerhan cells are made in the bone marrow and migrate to the surface of the skin and help fight infection.
  • Merkel cells are specialized skin cells that help with sensing light touch. They are located on the tips of fingers and toes as well as other specialized areas.

The dermis is the deeper layer of skin. It has two layers that are responsible for supporting the epidermis:

  • The papillary dermis is a thin layer of tissue located just beneath the epidermis and contains capillary blood vessels and a few elastic and collagen fibers.
  • The deeper reticular dermis contains large bundles of collagen and elastic fibers that run parallel to the skin surface. The collagen and elastic fibers are responsible for helping the skin resist injury from shearing or other types of trauma, and allow the skin to return to its resting state after being stretched or compressed. This is the layer where hair follicles, sweat glands and sebaceous glands are found.
Subcutaneous fat tissue underlies the layers of epidermis and dermis and provides extra cushioning for the skin. Beneath this layer lie muscle and bone.

Wound healing is an intricate process where the skin or other body tissue repairs itself after injury. In normal skin, the epidermis (surface layer) and dermis (deeper layer) form a protective barrier against the external environment. When the barrier is broken, an orchestrated cascade of biochemical events is quickly set into motion to repair the damage. This process is divided into predictable phases: blood clotting (hemostasis), inflammation, the growth of new tissue (proliferation), and the remodeling of tissue (maturation). Sometimes blood clotting is considered to be part of the inflammation stage instead of its own stage.
  • Hemostasis (blood clotting): Within the first few minutes of injury, platelets in the blood begin to stick to the injured site. This activates the platelets, causing a few things to happen. They change into an amorphous shape, more suitable for clotting, and they release chemical signals to promote clotting. This results in the activation of fibrin, which forms a mesh and acts as "glue" to bind platelets to each other. This makes a clot that serves to plug the break in the blood vessel, slowing/preventing further bleeding. 
  • Inflammation: During this phase, damaged and dead cells are cleared out, along with bacteria and other pathogens or debris. This happens through the process of phagocytosis, where white blood cells "eat" debris by engulfing it. Platelet-derived growth factors are released into the wound that cause the migration and division of cells during the proliferative phase.
  • Proliferation (growth of new tissue): In this phase, angiogenesis, collagen deposition, granulation tissue formation, epithelialization, and wound contraction occur. In angiogenesis, vascular endothelial cells form new blood vessels. In fibroplasia and granulation tissue formation, fibroblasts grow and form a new, provisional extracellular matrix (ECM) by excreting collagen and fibronectin. Concurrently, re-epithelialization of the epidermis occurs, in which epithelial cells proliferate and 'crawl' atop the wound bed, providing cover for the new tissue. In wound contraction, myofibroblasts decrease the size of the wound by gripping the wound edges and contracting using a mechanism that resembles that in smooth muscle cells. When the cells' roles are close to complete, unneeded cells undergo apoptosis
  • Maturation (remodeling): During maturation and remodeling, collagen is realigned along tension lines, and cells that are no longer needed are removed by programmed cell death, or apoptosis.

The wound healing process is not only complex but also fragile, and it is susceptible to interruption or failure leading to the formation of non-healing chronic wounds. Factors that contribute to non-healing chronic wounds are diabetes, venous or arterial disease, infection, and metabolic deficiencies of old age. 

Wound care encourages and speeds wound healing via cleaning and protection from reinjury or infection. Depending on each patient's needs, it can range from the simplest first aid to entire nursing specialties such as wound, ostomy, and continence nursing and burn center care.

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