Skin structure, wound healing, and dressings

Wound healing phases

Inflammatory phase

• Initiated immediately and lasts 3-4 days
• Marked by hemostasis (stopping bleeding) and phagocytosis (removal of debris and pathogens)

Proliferative phase

• Lasts until day 21 post-injury
• Collagen formation: A whitish protein substance that adds to the tensile strength of the wound
• Eschar formation may occur

Maturation phase

• Begins at day 21 and lasts up to 1-2 years
• Leads to scar formation

Types of healing

Primary intention (first intention)

• Tissue surfaces are closed with minimal tissue loss
• Example: Surgical incision

Secondary intention

• Extensive tissue loss prevents edges from being approximated
• Example: Pressure ulcer
• Longer repair time, increased scarring, and higher infection risk

Tertiary intention healing (delayed closure)

• Wound is left open for a period before closure
• Example: Abdominal wound left open for drainage before later closure

Classification of wound drainage

• Serous - Clear to brownish fluid from the serum portion of blood
• Sanguineous - Bright red, bloody drainage
• Serosanguineous - Pinkish drainage, a mix of blood and serum
• Purulent - Thick, yellow or yellow-green pus, indicating infection

How to measure wounds accurately

Measuring wounds is essential for assessing healing progress and treatment effectiveness. Proper wound measurement includes length, width, depth, and any tunneling or undermining. Below are the tools and steps for how to measure a wound.

Tools needed for wound measurement

• Disposable ruler (centimeters or millimeters)
• Sterile cotton-tipped applicator (for depth)
• Wound probe (for tunneling or undermining)
• Gloves (to maintain infection control)
• Transparent film grid (optional for tracing irregular shapes)

Step-by-step wound measurement

Measuring length and width

• Patient positioning: Ensure the patient is in the same position each time for consistency
• Use a ruler: Place a disposable ruler over the wound
• Length measurement: Measure from the longest point head-to-toe (cephalad to caudal)
• Width measurement: Measure perpendicular to the length, at the widest point from side to side
• Documentation format: Length × Width (e.g., 5.2 cm × 3.4 cm)

Measuring wound depth

• Insert a sterile cotton-tipped applicator into the deepest part of the wound
• Mark the level where it meets the wound edge (this should be perpendicular to the cotton applicator)
• Remove and measure against a ruler
• Example documentation: Depth = 0.8 cm

Measuring wound volume

• Measuring wound volume can be done by multiplying length, width, and depth
• Alternatively, measure the amount of hydrogel required to fill the wound

Steps for measuring tunneling and undermining

• Insert a sterile probe into the suspected tunnel/undermined area
• Measure using a ruler
• Use the clock method to describe location (e.g., “Tunneling at 3 o’clock position, depth 1.5 cm”)

Additional documentation details

• Shape and edges: Irregular, round, oval, jagged
• Tissue type: Granulation, slough, eschar
• Exudate: amount (none, scant, moderate, heavy) and type (serous, purulent, sanguineous)
• Periwound skin: Erythema, edema, maceration, induration

Types of dressing

Gauze dressings

• Names: Sterile gauze, non-sterile gauze, impregnated gauze
• Indications: Used for wounds with moderate to heavy exudate, surgical wounds, and packing deep wounds, and pressure injuries stages III, IV.
• Contraindications: Not ideal for dry wounds (can cause adherence and delay healing)

Transparent film dressings

• Names: Tegaderm, Opsite, Bioclusive
• Indications: Superficial wounds, abrasions, and partial-thickness wounds with minimal exudate; also used for IV sites and pressure injuries stages I, II.
• Contraindications: Should not be used on heavily exudating wounds or infected wounds

Hydrocolloid dressings

• Names: Duoderm, Comfeel, Tegasorb
• Indications: Light to moderate exudating wounds, pressure injuries stage II and shallow stage III, and venous leg ulcers. Helps maintain a moist wound environment.
• Contraindications: Not suitable for infected wounds or wounds with heavy exudate.

Hydrogel dressings

• Names: IntraSite Gel, Aquaform, Vigilon
• Types: Gel, sheet, or beads (for deep wounds)
• Indications: Dry wounds, burns, painful wounds, and wounds with necrotic tissue (autolytic debridement), and pressure injuries stages II, III, IV.
• Contraindications: Should not be used on heavily exudating wounds as it can cause maceration.

Foam dressings

• Names: Allevyn, Mepilex, Lyofoam
• Indications: Moderate to heavily exudating wounds, venous ulcers, pressure ulcers, and diabetic foot ulcers and pressure injuries stages II, III, IV. Provides cushioning.
• Contraindications: Not ideal for dry wounds or wounds with minimal exudate.

Alginate dressings

• Names: Kaltostat, Sorbsan, Algicell
• Indications: Heavy exudating wounds, infected wounds, and wounds with tunneling. Derived from seaweed, absorbs large amounts of fluid, and pressure injuries stages III, IV.
• Contraindications: Not recommended for dry wounds or wounds with minimal exudate.
• Characteristics: When an alginate dressing is removed, it can have a yellowish, tan, or brown color and may have a mild, but unpleasant odor. While the appearance and smell can be alarming, they are often normal and result from the interaction between the seaweed-based dressing and the wound’s exudate.

Collagen dressings

• Names: Promogran, Fibracol, Biostep
• Indications: Chronic non-healing wounds, pressure ulcers, wounds with granulation tissue, and pressure injuries stages II, III, IV.
• Encourages new tissue growth.
• Contraindications: Not for dry wounds or wounds with eschar. Avoid in patients with collagen allergies.

Antimicrobial dressings

• Names: Silvercel, Acticoat, Iodosorb
• Indications: Infected wounds, burns, surgical wounds at risk of infection, and pressure injuries stages II, III, IV. Contains silver or iodine to reduce bacterial load.
• Contraindications: Avoid in patients allergic to silver or iodine. Not recommended for long-term use due to potential cytotoxicity.