Skin Integrity

08/12/2009

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Wound Healing Pathophysiology

12/11/2009

Phases of Wound healing

  1. Inflammatory Phase
  2. Proliferative Phase
  3. Remodelling Phase
  • duration of phases depends on the extent of injury and healing environment

 

Inflammatory Phase

  • inflammation occurs at time of injury
  • prepares wound environment for healing
  • blood vessel constriction
  • thrombus formation
  • vasodilation
  • increased capillary permeability
  • phagocyte emigration
  • digest debris
  • neutrophils arrive first, ingest bacteria, gone by day 3-4
  • macrophages appear 24hr after injury, remaining for an extended period
  • macrophages function in phagocytosis
  • macrophages release growth factors stimulating epithelial cells proliferation and angiogenesis
  • wounds may heal in absence of neutrophils, they cannot heal without macrophages

Proliferation Phase

  • begins within 2-3 days of healing
  • lasts up to 3wks
  • function – tissue building to fill wound space
  • fibroblasts produce collagen and other intracellular elements required for wound healing
  • 24-48hrs post injury fibroblasts and vascular endothelial cells begin proliferation of granular tissue (the foundation of scar tissue)
  • tissue is fragile and bleeds easily during to the # of newly formed capillary buds
  • in primary intention healing, epidermal cells seal the wound within 24-48h
  • epithelial cells require a moist surface for proliferation, therefore will wait to migrate under newly formed scab.
  • In cases of excessive granular tissue formation, re-epitheliarization may be impeded. Chemical cauterization may be required to allow healing to proceed
  • collagen synthesis peaks at 5-7days, continuing for several weeks

Remodelling Phase

  • 3 wks post injury, continuing 6 months or longer
  • cycle of collagen synthesis and collagenolysis
  • wound tensile strength increases
  • wounds will not regain original unwounded tensile strength
  • sutures provide 70% of tensile strength of non wounded skin
  • at suture removal 1 week post surgery, wound has only 10%
  • tensile strength increases to 70-80% over the next 4 wks before plateau

Factors Affecting wound healing

  1. Malnutrition
  2. blood flow & O2 delivery
  3. Impaired Inflammatory and Immune Response
  4. Infection, Wound separation and foreign bodies

Martin, Glenn and Porth, Carol, Mattson. 2009. Pathophysiology Concepts of Altered Health States. 8th ed. Lippincott Williams and Wilkins. Philadelphia


Impetigo

28/08/2009

Etiology:

Impetigo is a very contagious infection of the skin. Impetigo is caused by Staphylococcus or Streptococcus bacteria.

Symptoms:

localized redness develops into small blisters that gradually crust and erode.

Affected Populations:

This condition is most common in children 2-6 years of age.

The homeless are vulnerable to bullous and non-bullous impetigo. It also occurs when breaks in the skin allow bacteria to enter. However, the skin does not have to break to develop impetigo. Complicated impetigo may result in cellulitis.


Virtilago (leukoderma)

27/08/2009

Virtilago is an autoimmune disease. Smooth, white patches appear on the skin in regions where the body’s immune system has attacked and caused the loss of melanocytes, the pigment-producing cells.