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Wound Healing and the Problem Wound. Craig A. Blum, MD Fellow Division of Plastic Surgery Department of Surgery Tulane University School of Medicine. Breast Reconstruction?. Free Tissue Transfer?. Digit Replants?. Facelifts?. Wounds . . Disclaimer. Game Plan. Wound Basics
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Wound Healing and the Problem Wound Craig A. Blum, MD Fellow Division of Plastic Surgery Department of Surgery Tulane University School of Medicine
Game Plan • Wound Basics • Test Questions – Shelf, ABSITE • Practical info – Taking care of wounds • Short and Sweet
History of Wound Healing • 1700 BC Papyrus: Lint/animal grease/honey • 100 BC Egypt: Wound closure preserved soul • 1000 AD Gun Powder • 1500 AD Hot Oil • 20th Century Scientific Method
Wounds • Customize treatment • No two patients OR wounds are identical 58y DM, Neuropathy: unaware of R foot gangrene
Cause • Condition of patient • Definitive management?
Wounds • Crush injury wound • Viability of the remaining tissues • Ability to salvage the extremity • Functionality of the limb if it can be salvaged
Wounds • Reconstructive Ladder • Simple to Complex Formal Debridement, Elevation/ABI’s Appropriate IV ABX, Wound Vac, Skin Graft
Review of Wound Healing • Three basic types of healing • Primary • Delayed Primary • Secondary
Primary • Wound surfaces opposed • Results optimal • Clean wounds
Delayed Primary • Left open initially • Edges approximated 4-6 days later • Less common
Secondary • Surfaces not approximated • Defect filled by granulation • Covered with epithelium • Dirty Wounds • No Steri Strips
Three Phases of Wound Healing • Inflammatory Phase • Proliferative Phase • Remodeling Phase
Inflammatory Phase • Hemostasis and Inflammation • 24-48 hours • Platelets thrombus, chemotaxis • NEUTROPHILS and MACROPHAGES • Debride • Growth factors
Inflammatory: Neutrophils • Attracted by inflammatory mediators • Oxygen-derived free radicals • Debride wound
Inflammatory: Macrophages • Debride (phagocytosis) • Proinflammatory cytokines • IL -1 (fever) • Growth factors (TGF-B) attracts FIBROBLASTS • NO (vasodilation)
Three Phases of Wound Healing • Inflammatory Phase • Proliferative Phase • Remodeling Phase
Proliferative Phase • Epithelization, Angiogenesis and Provisional Matrix Formation • Begins when wound is covered by epithelium • 48 h to 2-3 weeks • Production of collagen is hallmark • STRUCTURE • FIBROBLASTS
Epithelialization • Basal epithelial cells at the wound margin flatten (mobilize) and migrate into the open wound • Basal cells at margin multiply (mitosis) in horizontal direction • Basal cells behind margin undergo vertical growth (differentiation)
Proliferative: Fibroblast • Work horse of wound repair • Produce Granulation Tissue: well vascularized collagen, supporting cells
Wound Contraction • Actual contraction with pulling of edges toward center making wounds smaller • Myofibroblast: contractile properties • (Secondary intention)
Collagen Homeostasis • After Wounding (Optimal Healing) • 48 hours + • Collagen production begins • Synthesis with a net GAIN of collagen • Initial increase in tensile strength due to increased amount of collagen • 2-3 weeks to 2 years • Remodeling with No net collagen gain
Collagen • Fibroblast make type III collagen (Baby collagen) • Replaced by type I (mature) • Type 4 basement membrane • Normal Skin • collagen ratio 4 : 1 Type I/III • Hypertrophic Scar • collagen ratio 2 : 1 Type I/III
Three Phases of Wound Healing • Inflammatory Phase • Proliferative Phase • Remodeling Phase
Maturation Phase • Random to organized fibrils • Type III replaced by type I • Wound may increase in strength for up to 2 years after injury • Collagen organization • Cross linking of collagen
Sits up after hernia repair? • Wound strength increases slowly for 2 weeks • Rapidly for 4 weeks • By 6 weeks wound has gained 50% of its ultimate strength (80% is as good as it gets)
Impaired Wound Healing • FISTULA • FRIENDS • FB • Radiation • Infection • Epith • Nutrition • DM, distal obst
Wound Healing • To treat the wound, you have to treat the patient • Optimize the patient • Circulatory • Pulmonary • Nutrition • Associated diseases or conditions
Oxygen • Fibroblasts are oxygen-sensitive • PO2 < 40 mmHg collagen synthesis cannot take place • Decreased PO2: most common cause of wound infection • Healing is Energy Dependent • Proliferative Phase has greatly increased metabolism and protein synthesis
Edema • Increased tissue pressure • Compromise perfusion • Cell death and tissue ulceration
Infection • Decreased tissue PO2 and prolongs the inflammatory phase • Impaired angiogenesis and epithelialization • Increased collagenase activity