Wound Healing and Care

Phases of Healing - Speedy Recovery Stages

• Hemostasis: Immediate. Vasoconstriction, platelet aggregation (plug), coagulation cascade activation → fibrin clot.
• Inflammation (Substrate Phase): Days 1-4. Neutrophils (peak 24-48h), followed by Macrophages (key for transition). Phagocytosis, cytokine release.
• Proliferation (Fibroblastic Phase): Day 3 to 3 weeks. Fibroblasts deposit Collagen Type III. Angiogenesis (new vessels), granulation tissue. Epithelialization. Myofibroblasts cause wound contraction.
• Remodeling (Maturation Phase): 3 weeks to 1-2 years. Collagen Type III gradually replaced by stronger Type I. ↑ Tensile strength. Scar flattens.

⭐ Maximum tensile strength achieved is about 70-80% of original tissue, typically by 3 months.

Types of Healing - Gap Closing Goals

• Primary Intention: Clean wound, edges apposed (sutured). Minimal tissue loss. Goal: Rapid closure, fine scar.
• Secondary Intention: Edges not apposed, large defect. Heals by granulation, contraction, epithelialization. Goal: Body heals open wound.

  ⭐ Myofibroblasts are key for wound contraction in secondary intention.

• Tertiary Intention (Delayed Primary Closure): Initially left open (e.g., due to contamination), later surgically closed. Goal: Manage issues (infection), then close.

Factors Affecting Healing - Repair Roadblocks

• Local Factors:
  • Infection (Most common delay)
  • Poor perfusion/Hypoxia (pO₂ < 40mmHg impairs collagen synthesis)
  • Foreign body, Hematoma, Seroma, Necrotic tissue
  • Trauma, Tension
  • Radiation, Edema
• Systemic Factors:
  • Age (Advanced: ↓cell activity, ↓collagen)
  • Nutrition: ↓Protein, ↓Vit C, ↓Vit A, ↓Zinc, ↓Copper
  • Diabetes (DM) (↓PMN function, ↓angiogenesis, ↓collagen)
  • Meds: Steroids (↓inflammation, ↓collagen), Chemo, NSAIDs (early)
  • Smoking (↓O₂ delivery, ↑CO), Obesity (↓perfusion)
  • Systemic Illness: Uremia, Jaundice, Malignancy, Anemia (Hb < 10g/dL)

⭐ Vitamin C is crucial for hydroxylation of proline and lysine, essential for collagen cross-linking; deficiency leads to impaired healing and scurvy.

Wound Care Principles - Bandage & Beyond

• Dressing Goals: Protect, absorb exudate, debride, compress, deliver medication.
• Dressing Types & Key Uses:
  • Gauze: Packing, absorption.
  • Films (e.g., Tegaderm): Superficial wounds, autolytic debridement, visualization.
  • Foams: Moderate/heavy exudate, cushioning.
  • Hydrocolloids (e.g., Duoderm): Autolytic debridement, light/moderate exudate, occlusive.
  • Alginates: Heavy exudate, hemostatic, cavity wounds.
  • Hydrogels: Hydrate dry/necrotic wounds, slough removal.
• Negative Pressure Wound Therapy (NPWT/VAC):
  • Mechanism: Subatmospheric pressure (typically -75 to -125 mmHg).
  • Benefits: ↓edema, ↑granulation tissue, ↑perfusion, ↓bacterial load.
  • Indications: Acute, chronic, traumatic wounds; grafts/flaps.
  • ⚠️ Contraindications: Malignancy in wound, untreated osteomyelitis, non-enteric/unexplored fistulas, necrotic tissue with eschar, exposed vessels/organs.
• Bandaging: Apply distal to proximal; even, firm pressure; avoid tourniquet effect.

⭐ NPWT is generally contraindicated directly over exposed blood vessels, nerves, anastomotic sites, or organs due to risk of erosion or fatal hemorrhage. Use a protective barrier if unavoidable and monitor closely.

Complications of Healing - Scar Wars

• Hypertrophic Scar: Raised, red, itchy. Develops within weeks.
• Keloid: Rubbery, overgrows boundaries. Develops months later. Common in darker skin. 📌 KELOID: Keeps Extending.
• Contractures: Limit movement, deformity. Esp. joints, burns.
• Ulceration: Chronic non-healing.

  ⭐ Marjolin's ulcer: SCC in chronic wounds, burn scars, osteomyelitis sinuses.

• Others: Dyspigmentation, persistent pain, pruritus.

High‑Yield Points - ⚡ Biggest Takeaways

• Healing Phases: Inflammatory (PMNs, MΦ), Proliferative (fibroblasts, new vessels), Remodeling (collagen I for III).
• Collagen Facts: Type III (early) replaced by Type I (strong); max strength ~80% at 3 months.
• Wound Closure: Primary (sutured), Secondary (granulation), Tertiary (delayed primary).
• Major Inhibitors: Infection, hypoxia, malnutrition (Vit C, zinc), diabetes, steroids.
• Problematic Scars: Keloids grow beyond wound; Hypertrophic scars stay within boundaries.
• Myofibroblasts: Crucial for wound contraction, especially in secondary intention healing.