Wounds can exist as small as a scratch to a large gaping area down to a bone or organ like the intestines. Consequently, any opening in the top layer of skin constitutes a wound. A wound bed constantly changes to repair the exposed injured tissue. According to the text "World Wide Wounds," the cells, nerves and chemicals in the body work in a coordinated fashion to promote healing. Four overlapping phases of healing occur in the wound bed.
Significance of Platelets
After tissue damage and appearance of a wound, bleeding occurs to bring platelets and fibrin products to the area to form a clot. "World Wide Wounds" describes platelets as not only producing clotting in the wound bed with red blood cells, but also bringing growth factor proteins into the wound bed. The growth factor initiates the fibroblasts, endothelial cells and macrophages that lay the new cells down in the wound.
Role of Wound Inflammation
Platelets contain chemicals such as serotonin to open up the small blood vessels in the wound producing swelling and fluid or exudate in the wound bed. Within 24 hours of a new wound, white blood cells invade the wound bed and attach to blood vessels lining the site. These white cells clean the wound of bacteria and force any dead cells to the wound surface to slough off. A particular type of white cell called a macrophage appears in the wound at 48 hours and acts as a key regulatory cell to recruit the repair cells of fibroblasts and endothelial cells. The repair cells mend the disrupted blood vessels.
Function of Fibroblasts
At about day three post-injury, fibroblast cells produce granulation tissue or new tissue cells in the wound bed along with matrix fibrin proteins. The fibroblasts generate collagen as the foundation of the new tissue. Epidermal cells start to migrate across the wound surface to close the wound.
Tissue Remodeling
The collagen material increases in diameter to give the repaired tissue strength, but healed skin never returns to the original strength of the original site. The maximum strength achieved is only 80 percent of the original skin. The final phase of remodeling occurs with the tissue shrinking to bring the wound margins closer together as a scar.
Factors Inhibiting Healing of the Wound Bed
If a wound happens to be infected with an over-abundance of bacteria, the healing process slows as the body becomes unable to remove an excess of micro-organisms by the body's white cells. According to "Fundamental and Advanced Nursing Skills," antibiotics and wound cleaning or debridement become necessary before healing can proceed.
According to the text "Wound Repair and Regeneration," malnutrition slows wound repair by the body's inability to make available white cells, growth factors and other key repair cells for wound healing. Nutrients supplied by protein, carbohydrates and fats furnish the body with the building blocks for tissue restoration.
References
- "World Wide Wounds"; Wound Bed Preparation; K. Vowden, R.N. & P. Vowden, M.D.; 2002
- "World Wide Wounds"; Pathophysiology of Wound Healing; S. Enoch, Ph.D. & P. Price, Ph.D.; 2004
- "Fundamental and Advanced Nursing Skills"; G.B. Altman, Ph.D., et al.; 2010
- "Wound Repair and Regeneration"; Guidelines to Aid Healing of Acute Wounds by Decreasing Impediments of Healing; M. G. Franz, M.D., et al.; 2008
