Patho- Wound Healing
Tensile strength: primary intention
-Sutured wound: 70% strength. -After sutures are removed (one week), tensile strength is 10% -Tensile strength increases rapidly for 4 weeks then plateaus at 70-80% after 3 months
How long does inflammatory phase last?
1-2 days
What are the three ways to fill in the gap and restore continuity to the injured part?
Primary, secondary, and tertiary intention
When does proliferative phase occur?
3-4 days after
What is fibroblast?
A connective tissue cell that synthesizes and secretes collagen and other intercellular elements needed for wound healing.
Keloid
Abnormality in wound healing by scar tissue. Tumor-like mass caused by excess production of scar tissue.
What is the first step of wound healing?
Acute Inflammation
What does adequate wound healing require?
Adequate protein, CHO, fats, vitamins minerals. Protein for rebuilding tissue, CHO for energy, fats for cell membranes and synthesis of new cells, Vitamins A and C, and Zinc.
Wound separation in wound healing
Affects wound healing. Approximation of wound edges greatly enhances healing and prevents infection. Poor nutrition and lots of adipose tissue causes the wound to separate.
Foreign bodies (include sutures) in wound healing.
Affects wound healing. Foreign bodies invite bacterial invasion and delay healing.
Infection in wound healing
Affects wound healing. Impairs all dimensions of wound healing by prolonging inflammatory phase, impairing formation of granulation tissue, inhibiting proliferation of fibroblasts, and inhibiting deposit of collagen fibers.
Impaired inflammatory and immune responses in wound healing
Affects wound healing. Inflammation is an important first phase of wound healing that prevents infection.
What occurs during proliferative phase?
Building new tissue to fill in wound space using granulation tissue.
What is the key cell in proliferative phase?
Fibroblast
What is Epithelialization?
Final component of proliferative phase.It is the migration, proliferation, and differentiation of epithelial cells to wound edges to form new surface layer. These cells are similar to the cells originally there. It closes the wound from the outside in.
What allows for epithelialization to occur in wounds?
Formation of granulation tissue in an open wound allows epithelial cells to migrate across the new tissue to form a barrier between the wound and the environment.
What elements needed for wound healing does fibroblast secrete?
Growth factors that induce angiogenesis, and induce endothelial cell proliferation and migration.
Wound healing in ischemic tissue due to poor blood supply
Ischemic tissue become infected more readily
Secondary intention
Leaving it open, healing from the base up
Tertiary intention
Leaving the infected wound open until the infection is gone, and then closing it up.
What does contraction of scar tissue over joints and other body structures tend to do?
Limit movement and cause deformity
Evisceration
Organs pop out
What type of patients are at risk for foreign body invasion in wound healing?
Patients with orthopedic devices, cardiac pacemakers, dialysis catheters The infections may be difficult to treat; device may need to be removed.
What intention produces the least scaring?
Primary intention
When do cells stop dividing?
When they meet in the middle and hit each other.
What allows for the shrinking of the scar in secondary intention?
Wound contraction during proliferative and remodeling phases
Age related effects on wound healing
Wound healing progressively becomes more impaired with aging. Reduced collagen and fibroblast synthesis, impaired wound contraction, and slower reepilthelialization of open wounds causes delayed wound healing. Although delayed, most wounds do heal.
What occurs during remodeling phase?
Scar maturation and tensile strength increasing
What is the purpose of inflammation?
To prepare for wound enviornment for healing
How long does proliferative phase last?
Up to 2 weeks
What does the wound look like during proliferative phase?
Beefy red, fragile w/ lots of vascular tissue, bleeds easily
Who is prone to poor inflammatory response?
Diabetics due to poorly controlled blood glucose inhibiting phagocytosis. Small blood vessel disease is common in diabetics.
What occurs during inflammation?
Hemostasis controls the bleeding, vasodilation increases capillary permeability, plasma & blood components leak into injured area, Cellular Phase allows for debris removal & release of growth factors.
What affects inflammatory and immune responses in wound healing?
Immunosuppressive drugs, corticosteroids
Impaired blood flow and oxygen delivery during wound healing
Impaired ability to supply nutrients, remove resulting waste, and lack of oxygen needed for collagen synthesis. Affects wound healing.
What are the three steps of wound healing?
Inflammation, proliferative phase, and maturational or remodeling phase
When does remodeling phase occur and how long does it last?
Several weeks after and lasts for 2 years
What is tensile strength?
Strength before the injury
Dehiscence
Surgical wound pops open
Primary intention
Suturing the wound closed
What is also happening during remodeling phase?
Synthesis of collagen by fibroblasts and lysis by collagenase enzymes. It is building up and breaking down the tissue which is why it takes so long.