Wound Healing

MATURATION PHASE

The maturation phase is also termed as differentiation, resorptive, remodeling or the plateau phase of wound healing. The length of time the wound underwent during this period is about 21 days to months or for some it even takes years. The following events take place during the maturation phase:

  1. FIBROBLASTS LEAVE THE WOUND. About 3 weeks after tissue injury occurred, fibroblasts begin to leave the wound. The scar appears large reorganization of collagen fibers into tighter positions take place.
  2. TENSILE STRENGTH INCREASES. Collagen fibrils reorganization together with dehydration not only decreases the size of the scar but it also increases the tensile strength.
  3. COLLAGEN FIBERS REORGANIZE AND TIGHTEN TO REDUCE SCAR SIZE

Forms of Healing

As wounds are surgically managed, description of the wounds are described as either healing by first, second or third intention.

HEALING BY FIRST INTENTION (Primary Intention or Union)

When wound damage is minimal and the edges lie close to each other the healing would be described as primary healing or healing by first intention. Wounds made aseptically and properly closed by sutures heal with little tissue reaction. When tissue injury heals in this way, granulation of tissue is not visible and scar formation is minimal.

Primary intention wound healing is characterized by:

P – Presentable wound: wound is clean, made in a straight line with a little loss of tissue.

R – Reduced tension on the wound noted. All wound edges are well approximated wit sutures.

I – Indicated by rapid wound healing with minimal scarring noted.

The following processes take place when wounds heal by primary intention:

  1. The incised wound is filled up with blood clot. The presence of blood clot not only serves to minimize blood loss but also to seal the wound from dehydration and possible invasion of microorganisms. Early wound stabilization is also noted as the fibers of the blood clots bind to the elements of the intracellular matrix to the wound. When clots form, its surface that is exposed to the air dries out and together with some tissue debris produces a SCAB. Like any other injury, the body has natural defenses against infection, in the presence of a wound, acute inflammatory response forms a fluid exudates and delivers numerous inflammatory cells to the scene of the incision. Tissue debris is removed from the site by the phagocytic actions of the macrophages. Aside from removing tissue debris, the phagocytes also targets the clot by loosening and digesting it through the release of enzymes into it. During this process, entrapped red cells are broken down to yield pigments that results to the release of the hemoglobin. This contributes to the discoloration of the wound site early after the incision is made.
  2. Around 2 or 3 days after the injury, surface restoration and revascularization beneath the wound takes place because of the presence of the granulation tissue. Restoration of wound blood supply is made possible because new blood channels are recreated by the capillaries of the granulation tissues. Nourishment of the fibroblasts is now provided by the blood making the secretion of new collagen matrix and precollagen possible.
  3. Collagen formation builds strength to the wound. After 6 to 8 days the wound is usually strong enough to allow the removal of stitches. Strength is increased as formation of collagen continues and the dermal scar is formed. When keratin formation resumes, the scab loosens. Thus, it is easy for the scab to separate from the newly restored surface.
  4. Healing of the injured tissue is complete but the strength of the fully healed skin, although sufficient, never reaches the preinjury level.

HEALING BY SECOND INTENTION (Granulation)

When the edges of the wound is not closely apposed and are large, thereby producing more debris, healing that occurs is by secondary intention. With this type of healing, the process of restoring cell continuity is less and takes more time than the primary union.

Secondary intention wound healing characteristics are as follows:

S – Significant wound is present with a considerable tissue loss

E – Edges of the wound have not been approximated

C – Cells of granulation tissues set off natural wound healing

O – Observed pus formation or suppuration at the wound site

N – Natural wound healing is completed when skin cells grow over the granulations

D – Duration of healing takes longer and results in more scarring

 

Images courtesy of: eakoh.com, pilonidal.org, medical-dictionary.thefreedictionary.com

Daisy Jane Antipuesto RN MN

Currently a Nursing Local Board Examination Reviewer. Subjects handled are Pediatric, Obstetric and Psychiatric Nursing. Previous work experiences include: Clinical instructor/lecturer, clinical coordinator (Level II), caregiver instructor/lecturer, NC2 examination reviewer and staff/clinic nurse. Areas of specialization: Emergency room, Orthopedic Ward and Delivery Room. Also an IELTS passer.

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