PHASES OF WOUND HEALING
Inflammatory phase (Start of injury up to 4 days)
Hemostasis
Vasoconstriction occurs soon after the tissue is damaged as injured vessels release serotonin, histamine, prostaglandins, and blood. Platelet aggregation and thromboplastin form a clot as fibrin binds the edges of the wound together and provides temporary wound closure.
Inflammation (1 to 4 days)
Lymphocytes trigger the inflammatory response, which increases capillary permeability (this causes wound edges to swell). Bacteria and other cellular debris (dead cells) are consumed by white blood cells. This reduces the formed clot. Macrophages mediate by releasing growth factors which increase the level of fibroblasts.
Proliferative phase (2-3 days to 30 days)
Fibroblasts lay the building blocks of the new extracellular matrix for collagen fibers and granulation tissue. Granulation tissue forms and that tissue fills in the open space of the wound. Angiogenesis, with capillary formation, connects blood flow into the newly developing granulating tissue. The wound begins to contract and epithelialization moves across and covers the surface of the wound.
Remodeling phase ( 3 weeks to 2 years)
Completion of contraction occurs as collagen fibers shorten and crosslink reducing the size of the scar, but increasing . This increases the tensile strength of the scar which will return to be approximately 80% as strong as the original tissue.
Matthew Livingston R.N. C.W.S.
