What is wound healing?

What is wound healing?

Wound healing is a cascade of cellular events that happens after the skin is injured. The body is triggered to respond to help repair the wound and fill in the damage with new tissue. Acute wounds will follow a timely and predictable path toward wound closure. Surgical or trauma injuries should progress through the expected time frames for healing. A patient with comorbid risk factors could have delayed wound healing if factors are not addressed to prevent further tissue damage or injury reoccurrence. For instance, pressure injuries require pressure relief; diabetic wounds will need blood sugar management and vascular wounds will likely need new blood flow through revascularization. Wound healing will require management of how the wound was created and improving risk factors that may limit healing will help to prevent wound healing delays which can lead to chronic slow-healing wounds.

How a wound heals involves four overlapping processes, comprised of homeostasis, inflammation, proliferation and remodeling. Homeostasis happens in quick response to bleeding with blood vessel constriction. A fibrin platelet plug will bind and plug the hole with a clot formation. Homeostasis occurs from the time of injury to the first few minutes to hours. Applying pressure to a trauma wound is a common response to a cut or laceration. The pressure helps slow the blood flow and allows the clot to form.

The inflammatory phase is an immune response to bring white blood cells, growth factors, nutrients and enzymes to the wound to clean any debris and begin the repair process. Inflammation brings a normal bit of minor swelling and redness around the open area. Increased heat and pain can also be anticipated. Within the first 1-6 days of healing, inflammation is a normal response and is not of concern. If the inflammatory response continues past 7 days or symptoms continue to worsen, then infection may be a consideration. Infection may present as redness, pain and increased drainage. Drainage may become thick and odoriferous and edema can appear in the area. Identifying inflammation versus infection can be difficult in the early stages. Infection will not improve without treatment and those symptoms will continue to worsen.

When people take anti-inflammatories to manage pain; the inflammatory response may be blunted or delayed. This may help improve pain control associated with a wound; however, it may not improve or speed healing rates. The inflammatory response needs to occur as part of the wound healing process, otherwise healing may be stalled or become chronic. Surgical infections may have a delayed presentation until 2-3 weeks after surgery, especially when some people are given antibiotics prophylactically. Unfortunately, the body becomes less responsive to antibiotics the more often they are taken, and different antibiotics or treatments may be required if an infection after surgery does occur or persists after broad-spectrum antibiotics. Both anti-inflammatories and antibiotics have an effect on the gut microbiome which can cause a cumulative effect on the individual. In most instances, it is best to take only medications that are actively needed at the specific time and personalized as much as possible for optimal care.

The proliferative phase builds new granulation tissue to fill and approximate the wound edges. New blood vessels form to bring sufficient oxygen and nutrients to the new tissue. Collagen and the extracellular matrix will bring strength and flexibility to the new tissue forming. Healthy granulation tissue will be red, not pale pink, and may have a slightly bumpy appearance as new tissue buds are forming. Proliferation will be maximized in a moisture-balanced environment to encourage the debridement of non-viable tissue and encourage new cell growth. Moist wound healing is the standard of care for the majority of wounds except with poor circulation and low healing potential patients. A moist wound environment can be achieved by dressings that are occlusive and may require moisture donation by gels, ointments and impregnated packing materials.

The maturation phase or remodeling of wound healing is when the wound fully closes. Disorganized collagen fibers will remodel into cross-linked aligned fibers to improve scar formation, flexibility and strength. Remodeling takes roughly 21 days after injury and over a year to complete. The resulting scar will only be 80% as strong as the unwounded surrounding skin. While a scar is maturing it will continue to change. Color of scars will fade from purple to paler in color and may still be visible indefinitely depending on the size and shape of the original wound. Irregular scars like hypertrophic and keloids may be an issue that some individuals will have to deal with. The best indication of how someone will scar is to observe other scars on their own body. Keloids may need additional surgery or injections to improve. Scar tissue continues to grow and change, which can become a cosmetic issue as well as physically painful. Adhesions may benefit from manual manipulation, regular scar massage and fascial mobility.

When acute wounds heal normally, they should progress to close within a month. Silent inflammation and infection can stall wound progression and limit healing during any phase of healing. These issues will delay wound healing and cause chronic wounds. If wounds are not progressing within 1-2 weeks of starting a wound plan, then the plan should be adjusted. Adjustments can be made to the cleanser, primary and cover dressings or the frequency of change. More complex changes to medications or adjunctive healing modalities may be required if wounds become chronic and are complicated by comorbid status.

How the body heals a wound is a normal natural function of the integumentary and immune body systems If the body is not optimally functioning, then healing will be complicated and delayed. Mobility and circulation play an important role. If blood is not flowing, homeostasis and inflammatory response will be delayed and nutrients will not adequately reach the wound to heal. If inadequate nutrition, including hydration, is not available, a wound will not be able to heal. Adequate hydration is needed to help flush toxins from the body, support the immune system’s response and also help to keep blood vessels patent. The body will require more nutrients overall and protein is required to build new tissue. Wounds with heavy drainage will also require replenishment of protein lost. Nutritional wound standard recommendations exist as a starting point. However, if wounds are not healing will benefit from collaboration with a dietician to help optimize personalized nutrition for wound healing.

©2020 Human Biosciences, Inc. The content presented here is for your information only. It is not a substitute for professional medical advice.