Wound Healing

1
Wound Healing

• Susie Pease
• Return to Practice (Nursing)
• School of Healthcare Studies
• The University of Leeds

2
Stages of healing

• A complicated process all stages overlap
• Haemostasis commences immediately
• Inflammation 0 - 4 days
• Proliferation 4 - 24 days
• Maturation 24 days - 1 year

3
Haemostasis

• Blood leaks from a vessel into the tissues
  (extravasion of blood)
• This initiates vasoconstriction
• Platelet activation leads to coagulation
  (platelet plug)
• Physiological factors cause formation of a fibrin
  clot (to reinforce platelet plug)

4
Haemostasis
platelets
Aggregation of platelets
Activation of clotting cascade

Formation of fibrin
Clot forms
5
Inflammatory Phase

• Chemical mediators including histamine and
  serotonin attract leucocytes to area
• Release of prostaglandins causes vasodilatation
• Vasodilatation leads to increase in capillary
  permeability and inflammatory exudate
• Neutrophils and monocytes (which change to
  macrophages) attracted to area
• Neutrophils rid wound of contaminating bacteria
• Macrophages phagocytose pathogenic organisms
  scavenge tissue debris including old neutrophils

6
Stage 2 phagocytic vacuole formation
Neutrophil
7
Inflammatory Phase continued

• Oxygen and nutrients are required
• New blood vessels are formed (angiogenesis)
• Growth factors stimulate capillary endothelium to
  divide and direct the growth of new blood vessels

8
Angiogenesiscapillary buds grow towards wound
Dermis
Epidermis
Capillary bud
Capillary
Adipose tissue
9
Proliferative Phase

• As capillary loops are formed the area becomes
  oxygenated
• Macrophages and fibronectin stimulate fibroblasts
  to produce collagen, proteoglycans and elastin
• With proteoglycans, a glue like substance,
  collagen fills tissue space
• Elastin fibres give tissue its elasticity

10
Proliferative Phase cont.

• Angiogenesis provides oxygen and nutrients
• Vitamin C is essential for collagen formation
• Without Vitamin C there is inadequate cross
  linking of collagen fibres and a reduction in
  strength
• Iron, zinc, copper,vitamin A and protein are also
  essential elements in the wound healing process

11
Epithelialisation Contraction

• During proliferation two other processes occur
  simultaneously
• Wound contraction decreases size of wound
• Epithelialisation resurfaces wound
• Superficial skin loss - epithelialisation occurs
  from wound margins and hair follicles
• More extensive skin loss - occurs from wound
  edges

12
Maturation Phase

• Final stage starts about 3 weeks after injury
• Involves remodeling of collagen fibres which
  continues to become stronger
• Fibroblasts (collagen producing cells) migrate
  from wound
• Rationalisation of numerous blood vessels
• Scar shrinks, thins and pales

13
Healing by Primary Intention

• Follows a clean surgical type incision
• All phases of wound healing occur
• Minimal formation of granulation tissue
• Contraction has minor role
• Epithelialisation occurs over suture line

14
Secondary Intention

• Occurs where there is more extensive tissue loss
• Large amounts of granulation tissue therefore
  longer process
• Greater wound contraction required
• Fibrous scar formation
• Proliferative and maturation phases longer

15
Factors which delay healing

• Intrinsic Factors
• Age
• Disease processes
• Psychological status
• Body image

16
Extrinsic Factors

• Poor surgical technique or wound care
• Malnutrition
• protein / energy malnutrition
• Vit A C, zinc, copper, iron - collagen
  synthesis
• Dehydration
• Drug therapies
• Radiotherapy
• Smoking

17
Signs of Normal Wound Healing

• New wound red and raw
• 2 - 3 days inflammation
• Exudate depends on size of wound - lessens but
  some persists to complete epithelialisation
• Granulation tissue - pale pink or yellowy bumpy
  cobblestone appearance
• New epithelium - pale pink

18
Signs of delayed healing

• Generalised malaise of patient
• Pyrexia and tachycardia
• Wound begins to discharge
• Area around wound - red, sore, swollen, indurated
• On removal of suture - pus discharged
• Partial or complete wound breakdown on removal of
  sutures

19
Slough

• yellow or white
• dead, devitalised tissue, dry or moist
• commonly lines base of chronic wounds

20
Necrotic Tissue

• Black or blackish green
• Dead tissue
• Hard, leathery or soft and moist
• Adherent to underlying tissue

21
Suggested Reading

• Bale S., Harding K. Leaper D (2000) An
  Introduction to Wounds. Emap Healthcare.
• Dealey C. (1999) The Care of Wounds. (2nd
  Edition) Blackwell Science.