Wound healing

1. Wound Healing
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Arua Institute of Health Science
By
William Edema

2. Objectives
 Explain wound healing by both
primary and secondary intention
 Outline factors that influence
wound healing
Content:
 Define a wound healing.
 Describe the mechanism of Healing
 Healing by primary intention
 Healing by secondary intention
 Outline the broad groups of cells
 Labile cells
 Stable cells
 Permanent cells
INTRODUCTION TO PATHOLOGY
Topic 2.1.1: Wound Healing (Tissue Repair)

3. Overview
▶ Wounds
▶ Wound Healing Process (WHP)
▶ Chronic Wounds
▶ Wound Care
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4. Overview
▶ Wounds
▶ Wound Healing Process (WHP)
▶ Chronic Wounds
▶ Wound Care
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5. Wound
▶ Wound is a
circumscribed injury
which is caused by
an external force and
it can involve any
tissue or organ.
Wound edge Wound
corner
Surface of
the wound
Base of the wound
Cross section of a simple wound
Skin surface
Subcutaneus tissue
Base of the wound
Wound edge
Surface of
the wound
Wound
cavity
Superficial fascia
Muscle layer
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6. DEFINITION OF A WOUND
A wound is a break in the skin, which may result from physical, mechanical or thermal
damage, or develop as a result of the presence of an underlying medical or
physiological disorder. For example:
▶ Physical damage: pressure ulcers
▶ Mechanical damage: abrasions, grazes, lacerations, knife wounds (surgery), or
bullet wounds and bites etc.
▶ Thermal damage: burns caused by flames, chemicals, radiation, friction or
electricity and frostbite.
▶ Medical or physiological disorder: arterial or venous ulcers, autoimmune,
endocrine, dermatology and haematological disorders, wounds associated with
certain systemic infections, malignant diseases or neuropathy.
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7. Wounds
▶ Intentional Wounds: result from planned treatment
▶ Unintentional Wounds: result from unexpected trauma…accident/ burns/ shooting
▶ Open Wounds: skin broken, portal of entry
▶ Closed Wounds: trauma from force, skin intact, soft tissue damage, internal injury, possible
bleeding
▶ Acute Wounds: go through normal/timely healing process
▶ Chronic Wounds: fail to go through normal stages of healing; no timely progress in
healing
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8. Wound Classification
▶ Accidental Wounds
▶ Based on the bacterial contamination
▶ Based on the depth of wounds
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9. Accidental Wounds
Classification based on origin
Wounds caused by
▶ Mechanical forces
▶ Chemicals
▶ Radiation
▶ Thermal forces
▶ Special
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10. Accidental Wounds
Classification based on origin
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▶ Mechanical
▶ Abraded wound (vulnus abrasum)
▶ Puncured wound (v. punctum)
▶ Incised wound (v. scissum)
▶ Cut wound (v. caesum)
▶ Crush wound (v. contusum)
▶ Torn wound (v. lacerum)
▶ Bite wound (v. morsum)
▶ Shot wound (v. sclopetarium)
▶ Chemical
▶ Acid
▶ Base
▶ Wounds caused by radiation
▶ Wounds caused by thermal forces
▶ Burning
▶ Freezing
▶ Special
▶ Toxic, venoms
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11. Classification of wounds
Based on bacterial contamination
▶ Clean wound
▶ Clean-contaminated wound
▶ Contaminated wound
▶ Heavily contaminated or dirty wound
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12. Classification of wounds
Depending on the depth of injury
Superficial
Partial thickness
Full thickness
Deep wound
+ bone, opened cavities, organs…etc.
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13. Acute and Chronic Wounds
 Acute wounds in normal, healthy individuals heal through an
orderly sequence of physiological events that include
hemostasis, inflammation, epithelialization, fibroplasia, and
maturation.
 When this process is altered, a chronic wound may develop
and is more likely to occur in patients with underlying
disorders such as peripheral artery disease, diabetes, venous
insufficiency, nutritional deficiencies, and other disease states.
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14. Overview
▶ Wounds
▶ Wound Healing Process (WHP)
▶ Chronic Wounds
▶ Wound Care
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15. Wound Healing
The purpose of acute inflammation is to eliminate the pathogenic insult and
remove injured tissue.
▶ Healing is the restoration of integrity to an injured tissue.
▶ Regeneration is the renewal of a lost tissue or part in which the lost cells are
replaced by identical ones through proliferation.
▶ Repair is the orderly process by which a wound is eventually replaced by a scar.
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16. Classification of cells by proliferative
potential
▶ Labile cells are found in tissues that are in a constant state of renewal (skin).
▶ Stable cells are found in tissues that normally are renewed very slowly (liver).
▶ Permanent cells are terminally differentiated and have lost all capacity for
regeneration (neurons).
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18. Phases of Wound Healing
▶ Inflammatory Phase
▶ Proliferative Phase
▶ Remodeling Phase
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19. 18
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20. Phases of Wound Healing
▶ Inflammatory phase (0-4 days)
▶ Vasoconstriction
▶ Hemostasis
▶ Clot formation
▶ Proliferative phase (2-3 days to 30 days)
▶ Fibroblasts lay framework for ECM and new granulation
▶ Angiogenesis connects new granulation
▶ Epithelialization progresses across wound base
▶ Remodeling phase (3 weeks to 2 years)
▶ Completion of wound contraction with crosslinking of collagen and reduction in scar size
▶ Tensile strength ultimately becomes nearly 80% of original
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23. Phases of Wound Healing
Inflammatory Phase
Vasoconstriction
Hemostasis
Clot formation
Proliferative Phase
Angiogenesis
Granulation
Epithelialization
Remodeling Phase
Epidermis maturation
Wound contraction
Apoptosis & scar maturation
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https://youtu.be/CT-xILciPHo?t=1793

24. Inflammatory Phase
▶ Vasoconstriction
▶ Hemostasis
▶ Platelet Aggregation
▶ Clotting Cascade
▶ Growth Factors Secretion
▶ Fibrin Matrix
▶ Scaffold for wound healing process
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25. Selected growth factors important to
wound healing
▶ EGF (epidermal growth factor). Stimulates wound re-epithelialization and stimulates
blood vessels and fibroblasts.
▶ FGF (fibroblast growth factor). Stimulates new blood vessel and collagen formation.
▶ PDGF (platelet derived growth factor). Attracts/stimulates smooth muscle cells,
fibroblasts, and other cells. Important in ECM formation.
▶ TGF-β (transforming growth factor-beta). Slows buildup of epithelial cells,
suppresses immunoglobulin secretion and is helpful in ECM formation.
▶ TNF-a (tumor necrosis factor-alpha). Activates neutrophils, causes fibroblasts to
multiply, causes bone/cartilage resorption.
▶ IL-1 (interleukin-1). Attractant for epithelial cells, neutrophils, mono and lymphocytes;
also stimulates collagen synthesis.
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29. Wound Healing Phases
Cell Types
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31. Proliferative Phase
▶ Angiogenesis or
Neovascularization
▶ Granulation
▶ Epithelialization
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32. Proliferation or Granulation
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▶ Fibroblasts synthesize and secrete collagen
and other intercellular elements that
needed for wound healing
▶ Fibroblasts also produce FGF that needed
for angiogenesis, wound contraction and
matrix deposition
▶ Fibroblasts and vascular epithelial cells
begin proliferating and form granulation
tissue that serves as the foundation for scar
tissue development

33. Remodeling Phase
▶ The principle cell involved in this process is the fibroblast. When the levels of
collagen production and degradation equalize, the maturation phase of tissue
repair is said to have begun] During maturation, type III collagen, which is
prevalent during proliferation, is replaced by type I collagen. Originally
disorganized collagen fibers are rearranged, cross-linked, and aligned along
tension lines.
▶ Remodeling can take up to 2 years after wounding.
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34. Overview
▶ Wounds
▶ Wound Healing Process (WHP)
▶ Chronic Wounds
▶ Wound Care
33

35. Chronic Wounds
 Acute wounds in normal, healthy individuals heal through an orderly
sequence of physiological events that include hemostasis, inflammation,
epithelialization, fibroplasia, and maturation.
 Chronic wounds are arrested in one of these stages, usually the
inflammatory stage, and cannot progress further.
▶ Chronic wounds are generally associated with physiological impairments
that slow or prevent wound healing. When this process is altered, a chronic
wound may develop and is more likely to occur in patients with underlying
disorders such as peripheral artery disease, diabetes, venous insufficiency,
nutritional deficiencies, and other disease states.
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36. Chronic Wounds Appearance
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37. Chronic Wounds - Necrotic
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38. Chronic Wounds - Sloughy
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39. Chronic Wounds - Granulating
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40. Chronic Wounds - Epithelializing
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41. Impaired Wound Healing
Local Factors
▶ Inadequate blood supply
▶ Increased skin tension
▶ Poor surgical apposition
▶ Wound dehiscence
▶ Poor venous drainage
▶ Presence of foreign body and foreign body
reactions
▶ Continued presence of micro-organisms &
Infection
▶ Excess local mobility, such as over a joint
Systemic Factors
▶ Advancing age and general immobility
▶ Obesity
▶ Smoking
▶ Malnutrition
▶ Deficiency of vitamins and trace elements
▶ Systemic malignancy and terminal illness Shock of
any cause
▶ Chemotherapy and radiotherapy
▶ Immunosuppressant drugs, corticosteroids,
anticoagulants
▶ Inherited neutrophil disorders, such as leucocyte
adhesion deficiency
▶ Diabetes and CRF 10/27/2017
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42. Overview
▶ Wounds
▶ Wound Healing Process (WHP)
▶ Chronic Wounds
▶ Wound Care
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43. Factors Affecting Wound Healing
An individual's ability to heal and the time required can vary greatly, and are influenced by the following factors, which
should be taken into consideration during assessment:
▶ General physical and psychological health and type and level of concurrent illnesses
▶ Treatment: systemically and locally
▶ Nutritional and hydration status
▶ Type of wound, location, depth and extent of damage and type of tissue in wound
▶ Wound temperature, moisture level and pH balance
▶ Levels of bacterial colonisation and infection
▶ Blood supply to the wound and surrounding area & oedema of surrounding tissues
▶ Disruption to normal sleep pattern
▶ History of smoking and alcohol consumption
▶ Medications such as steroids, immune-suppressants and chemotherapy.
▶ environment
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44. Wound Management
▶ Wound Bed Preparation (WBP)
▶ Wound Debridement
▶ Infection Prevention & Control
▶ Effective Exudate Management
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45. Wound Management
▶ Wound Debridement: Debridement is the removal of necrotic, devitalised, sloughy or infected tissue,
or foreign bodies from a wound. The body can debride itself by a natural process called autolysis;
however, this may take time if large amounts of slough are present. Slough can provide an environment
for bacteria to thrive, increasing the risk of infection. Debridement is recommended as a principle of
wound management
▶ Autolytic debridement: where the body gradually sheds itself of devitalised tissue. This process can be
augmented by the use of dressings such as hydrogels, hydrocolloids or capillary action dressings, alginates,
foams, antiseptic dressings.
▶ Bio-surgery: sterile larvae (maggots)
▶ Sharp debridement: using a sterile blade, scalpel or scissors. This should only be undertaken by a healthcare
professional with specific training and competence.
▶ Surgical debridement: used when there is an urgent clinical need to remove or drain devitalised tissue and when
fast debridement would speed patient recovery. If this is required the patient should be referred to a surgeon.
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46. Wound Management
▶ Effective Exudate Management: PRINCIPLE OF MOISTURE BALANCE
▶ Drier wounds, (except those with poor circulation), should be moistened with
dressings that hydrate tissue, e.g. hydrogels, hydrocolloid sheets and pastes.
▶ Wounds with excess exudate require dressings that absorb or control fluid, e.g.
alginates, hydrofibres, capillary action, foams, Negative Pressure Wound
Therapy (NPWT) and compression bandages and hosiery.
▶ Surrounding intact skin should be protected from exudate with barrier films,
creams and absorbent dressings as it can cause excoriation.
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47. Local Wound Care
▶ Debridement
▶ Surgical
▶ Autolytic
▶ Enzymatic
▶ Biological
▶ Moisture Balance
▶ Foams
▶ Calcium alginates
▶ Hydrogels
▶ Hydrocolloids
▶ Adhesive films
▶ Negative pressure therapy
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Cover & Protect
Wound
Stimulate
Healing
Promote
Moist
Environment
Cover & Protect
Wound
Phase-I:
Traditional Wound Care
Phase-II:
Advanced Wound Care
Dry Bandages,
Adhesives & Dressings
Moisture Agents,
hydrocolloids, foams,
hydrogels, alginates
Improved dry bandages,
dressings and devices
Active Agents
(Biologics, cell
engineering, etc.)

49. Wound Management: World Market
The World Market for Wound Management encompasses twelve product segments:
▶ Traditional Adhesive Dressings
▶ Traditional Gauze Dressings
▶ Non-Adherent Dressings
▶ Film Dressings
▶ Foam Dressings
▶ Hydrogel Dressings
▶ Hydrocolloid Dressings
▶ Alginate Dressings
▶ Antimicrobial Dressings
▶ Negative Pressure Wound Therapy
Devices
▶ Bioengineered Skin and Skin Substitutes
▶ Wound Care Growth Factors
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50. Global Wound Care Market
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51. Worldwide Wound Management Market,
Segment Size & Growth, 2013-2021
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52. Advanced Wound Care
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53. Advanced Wound Care
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