The Royal Marsden Hospital Manual of Clinical Nursing Procedures - Lisa Dougherty [633]
External: mechanical (friction, surgery), chemical, electrical, temperature extremes, radiation, micro-organisms.
Internal: circulatory system failure (venous, arterial, lymphatic), endocrine (diabetes), neuropathy, haematological (porphyria cutanea tarda, mycosis fungoides), malignancy (fungating wound, Marjolin’s ulcer (Naylor et al. 2001)).
Anatomy and physiology
The skin is the largest organ in the body and makes up about 10% of the adult total bodyweight (Hess 2005). The skin is important as it functions as an outer boundary for the body and helps preserve the balance within (Soloman et al. 1990). The skin needs to remain intact to perform vital functions (Timmons 2006) and without it humans would not survive insults from bacterial invasion or heat and water loss (Marieb and Hoehn 2010).
The skin varies in thickness from 1.5 to 4 mm depending upon which part of the body it is covering (Marieb and Hoehn 2010). The skin is made up of two main layers, the dermis and epidermis, which have six main functions: protection, sensation, thermoregulation, metabolism, excretion and non-verbal communication (Hess 2005, Timmons 2006).
The epidermis is the outermost layer and is avascular and thin. It regenerates every 4–6 weeks and functions as a protective barrier, preventing environmental damage and micro-organism invasion (Hess 2005). The thickness of the epidermis varies and it is thicker over the palms of the hands and soles of the feet (Marieb and Hoehn 2010).
The dermis provides support and transports nutrients to the epidermis. It contains blood and lymphatic vessels, sweat and oil glands and hair follicles. The dermis is made up of collagen and fibroblasts, elastins and other extracellular proteins which bind it together and keep it strong (Hess 2005). Its extracellular matrix (ECM) contains fibroblasts, macrophages and some mast cells and white blood cells (Marieb and Hoehn 2010). The connective tissue within the dermis is highly elastic and provides strength to maintain the skin’s integrity and combat everyday stretching and wear and tear (Timmons 2006).
The subcutaneous layer just below the dermis is the deepest extension and binds the skin to underlying tissues (Solomon et al. 1990). This layer is known as the hypodermis or superficial fascia and stores fat. It also assists the body as a protective layer and allows movement (Marieb and Hoehn 2010).
Related theory
Classification of wounds
There are many different wound classification systems available and choice depends on the type of information required. A wound may be classified simply according to the method of healing, for example primary, secondary or tertiary intention (Miller and Dyson 1996), but this does not provide any information about the wound’s characteristics. Further simple classification systems include whether the wound is acute (of short duration), chronic (of long duration) or according to the amount of tissue loss (Dealey 2005). A classification system that contains an appraisal of tissue loss is considered most useful (Flanagan 1996). Superficial, partial-thickness wounds are usually traumatic and painful, but retain the hair follicles or sweat glands and part of the dermis and are usually considered acute wounds, whilst full-thickness wounds destroy the dermis and some deeper layers may also be involved (Dealey 2005). Full-thickness wounds take longer to heal and can be life threatening if necrosis or infection complicates healing (Hampton and Collins 2004), and are therefore chronic wounds.
Evidence-based approaches
Methods of wound healing
Wound healing is the process by which damaged tissue is restored to normal function. Healing may occur by primary, second or tertiary intention. Healing by primary intention involves the union of the edges of a wound under aseptic conditions, for example, a laceration or incision that is closed with sutures or skin adhesive (Dealey 2005, Miller and Dyson 1996).
Healing by secondary intention occurs when the wound’s edges cannot be brought together. The wound is left open and allowed to