Lecture 3: Wound Healing Part 1

Wound Care

Introduction to Wound Healing

  • Presented by Morgan Cummings, PT, DPT, GCS

Objectives

  • Review the anatomy and physiology of the Integumentary System

  • Identify stages of wound healing

  • Differentiate between normal and abnormal wound healing

  • Identify signs and symptoms of wound infection

  • Discuss PT interventions to promote wound healing

Review of the Integumentary System

Skin Facts

  • Largest organ in the human body

  • Approximately 300 million skin cells on average

  • Cells replaced roughly every 28 days

  • Skin thickness: 0.2 mm (eyelids) to 1.4 mm (feet)

  • At least 5 types of receptors for pain and touch

Skin Functions

  • Protection

  • Sensation

  • Regulating body heat (insulation and secretion)

  • Prevention of fluid loss and gain

  • Vitamin D synthesis

  • Aesthetic appearance

Anatomy of the Skin

  • Composes of various structures:

    • Epidermis

    • Dermis

    • Subcutaneous Tissue

    • Capillaries

    • Sweat Glands

    • Hair

    • Sebaceous Glands

    • Sensory Nerve Ending

Epidermis

  • Composed of 5 layers:

    • Stratum corneum

    • Stratum lucidum

    • Stratum granulosum

    • Stratum spinosum

    • Stratum basale

  • Role: primary protection

  • Avascular, composed of epithelial cells (keratinocytes)

Dermis

  • Divided into 2 layers:

    • Papillary dermis

    • Reticular dermis

  • Role:

    • Sensation (contains mechanoreceptors, thermoreceptors)

    • Secretion (contains appendages like hair follicles)

    • Protection (contains leukocytes)

  • Highly vascular and made of connective tissues (collagen and elastin)

Basement Membrane and Hypodermis

  • Basement Membrane:

    • Made of extracellular matrix, providing support and attachment to other layers.

  • Hypodermis (Subcutaneous Layer):

    • Composed of loose connective and adipose tissue.

    • Highly vascular.

    • Functions:

      • Protection (cushioning)

      • Assists in thermoregulation

      • Stores energy and fat-soluble vitamins

      • Supports the dermis

  • Deeper Structures: include muscles, ligaments, tendons, bones.

Wound Healing

Wound Closure Types

  • Primary Intention:

    • Surgical closure; heals in about 7 days.

    • Accelerated healing but still passes through healing phases.

  • Secondary Intention:

    • Wound heals through 4 phases; acute wounds can close in 3-4 weeks, chronic wounds take much longer.

    • Wound dehiscence refers to reopening of a surgical wound left to heal via secondary intention.

  • Tertiary Intention:

    • Contaminated wounds left open for cleansing and later closed surgically.

Phases of Wound Healing

  1. Hemostasis: Goal is to stop bleeding; occurs immediately after injury.

  2. Inflammation: Creates a clean wound bed; occurs from day of injury to day 10.

  3. Proliferation: Aims to close the wound bed; occurs from day 3 to week 2-3.

  4. Maturation (Remodeling): Focused on full wound closure and forming scar tissue; occurs from day 9 to >2 years.

Factors Affecting Wound Healing

Wound-Specific Factors

  • Mechanism of onset

  • Time since onset

  • Location and dimensions of the wound

  • Temperature and hydration of the wound

  • Presence of necrotic tissue/foreign bodies

  • Infection and inappropriate wound care (compliance issues and dressing types)

Systemic Factors

  • Lifestyle:

    • Smoking, alcohol use, stress

    • Nutrition:** Essential nutrients include iron, vitamin B12, vitamin C, zinc, protein.

  • Comorbidities:

    • Peripheral vascular disease, diabetes, immunocompromised conditions.

  • Age:

    • All phases of healing can be slowed with age.

External Factors

  • Pressure, shear, and friction can impair healing.

Abnormal Wound Healing

  • Wounds can become stuck in any phase, causing different characteristics:

    • Chronic inflammation

    • Hypergranulation (during proliferation)

    • Hypogranulation and delayed re-epithelialization (during maturation)

    • Epibole (rolled edges)

    • Dehiscence (insufficient tensile strength of scar tissue)

    • Formation of hypertrophic scars or keloids.

  • Chronic wounds do not heal within six weeks under optimal conditions.

Infection

Continuum of Wound Infection

  • Contamination: presence of microorganisms that do not impact healing.

  • Colonization: microorganisms successfully replicate without affecting healing.

  • Infection: microorganisms proliferate, overwhelming the immune system and impacting healing:

    • Local infections stay within wound boundaries.

    • Spreading infections extend beyond the wound perimeter.

    • Systemic infections can lead to severe outcomes like sepsis.

Preventing Infection

  • Universal Precautions: mandatory hand washing for all patients.

  • Standard Precautions: used for suspected infections; includes gloves and hygiene practices.

  • Sterile vs. Clean Techniques:

    • Clean techniques are standard for typical wounds.

    • Sterile techniques used for high-risk patients.

Signs & Symptoms of Infection

  • Local Symptoms:

    • Erythema, warmth, edema, increased exudate.

    • Subtle signs include undermining, hypergranulation, and new pain.

  • Spreading Symptoms:

    • Fever, confusion, elevated white blood cell counts, malaise.

  • Silent Infections: hard to detect in immunocompromised patients due to lack of classic signs.

Diagnosing Infection

  • Wound culture, tissue biopsy, blood tests, fluid aspiration.

Managing Infection

  • Antimicrobial Therapy: using impregnated dressings (silver, honey), topical agents, systemic antibiotics.

  • Antiseptic therapy: includes hand hygiene and specific antiseptics.

  • Debridement: necessary for removing infected or necrotic tissue.

Assessment & Treatment of Wounds

  • Further discussion to occur in lab settings.