The epidermis is the outer or cuticle layer of the skin, and consists of several layers of cells. It contains no blood vessels or nerve endings and its main function is to protect the underlying dermis. It has four or five different layers of cells depending on its location. From the deepest to the most superficial these are the:

Overexposure to sunlight can cause sunburn and skin cancers such as malignant melanomas and non-melanotic skin cancers (NMSC), primarily basal cell and squamous cell cancers. The number of people developing skin cancers in England has been rising rapidly in recent years. Cancer Research UK (2005) state that malignant melanomas are diagnosed in approximately 8000 people each year in the UK and the incidence has quadrupled in British males between 1975 and 2001 and tripled in females. The increase in incidence is thought to be due to intermittent sun exposure of untanned skin during holidays and other outside activities. However, there is increasing concern and evidence regarding the use of sun beds and the development of malignant melanoma (Diffey 2007). A number of skin cancer and skin damage prevention campaigns and activities are important, including Sun Smart campaign (Cancer Research UK 2007). The National Institute of Health and Clinical Excellence (NICE 2006) guidelines provide advice on how healthcare services for individuals with skin tumours should be organized.

Langerhans cells are thought to be important in the body’s immune responses. They absorb small particles of foreign material such as nickel in jewellery and are responsible for setting up the allergic reaction common in contact allergic eczema (dermatitis). The resultant rash usually clears up within 1 week following removal of the irritant once it has been identified. Key to managing this condition, in the long term, lies in identifying and avoiding contact with the allergen.

Three types of glands are present in the skin:

Information on hair and nails can be found in Chapter 14, ‘Hygiene’.

The production of sweat by the sudoriferous glands during hot weather helps reduce the body temperature through a process of evaporation. Changes in blood flow also occur. During hot weather peripheral blood vessels dilate, enabling heat loss by radiation. Conversely, in cold weather peripheral blood vessels constrict in order to maintain vital organs at an optimum temperature for functioning (see Ch. 7, ‘Homeostasis’).

Tortora & Grabowski (2003) identify two further functions of the skin: immunity, due to the action of the Langerhans cells; and as a blood reservoir, due to the ability to divert blood to muscles during exercise through vasoconstriction.

This type of healing occurs when the edges of the wound are opposed, as in a surgical incision. Healing tends to be rapid due to the close proximity of the wound edges (Fig. 15.2), and involves:

This type of healing occurs where there is a significant loss of tissue or where the skin edges are not opposed, as in an ulcer. Healing tends to be slower, but the exact time will depend on the extent of the damage (Fig. 15.3). It involves:

Tissue viability experts are now using a slightly different definition of wound healing involving four major stages – inflammation, proliferation re-epithelialization and matrix formation/remodelling (Calvin 1998). These terms are not yet commonly used in physiology and tissue viability text but are terms to look for in the future.

Benbow (2005) uses the term ‘tertiary healing’ to describe a wound where there is a significant delay between injury and wound closure; for example, extensive tissue loss or dehiscence. Bale & Jones (2006) use a similar term, ‘healing by third intention’, to identify a wound containing a foreign body or infection that is left open until the problem has been resolved.

The optimum temperature for human cell growth is 37 °C. Wounds kept at a constant temperature of 37 °C will heal faster than those exposed to thermal shock (i.e. extreme changes in temperature). To keep wounds at a constant temperature, unnecessary wound cleansing and dressing changes should be avoided.

The exudate produced by wounds, other than non-healing chronic wounds, contains nutrients, enzymes and growth factors that can aid the healing process. Lytic enzymes found in the exudate autolyse (break down) any necrotic tissue present, and growth factors increase the development rate of cells and result in less scarring. In such wounds, a moist wound environment facilitates wound healing, reduces the amount of tissue inflammation, produces less scarring and results in less pain for the patient. If the wound is allowed to dry out, a scab or eschar forms. This impedes cell migration and consequently slows down the healing process. Excessive exudate needs to be contained to prevent damage to the surrounding skin.

Exudate in non-healing chronic wounds is different in nature to that from acute wounds and has potentially harmful constituents which may inhibit wound healing (Vowden & Vowden 2003). Management of such exudate is part of an overall wound management approach to these chronic wounds, namely wound bed management (see Care Delivery Knowledge). An understanding of the role of exudate in the wound healing process is essential (see section on Annotated Further Reading: Vowden & Vowden 2003)

All cells require oxygen in order to develop and mature. An integral blood supply is therefore essential to ensure that cells receive an adequate oxygen supply in order to remain viable. The external administration of oxygen to the wound site, for example via an oxygen mask and tubing, will not benefit tissue perfusion, but will dry the wound site and delay wound healing.

The presence of foreign bodies and dead or devitalized tissue delays wound healing and provides a focus for infection, which will in turn also delay wound healing.

Wounds may be contaminated transiently or colonized by bacteria which do not affect wound healing adversely. Moore & Cowman (2007) suggest that whether or not an infection develops depends on the individual host’s response to bacteria present and the virulence of the bacteria. If wounds become infected, the bacteria present in the wound cause host damage and delay healing (see section on Annotated Further Reading: Benbow 2005). However, there is a stage called critical colonization that precedes clinical infection, causing delayed healing and subtle signs of infection (Collier 2002). Early diagnosis and prompt treatment of critical colonization to prevent overt clinical infection presents a challenge to health care professionals.

Images in the media of suntanned, high profile individuals such as fashion models may help to encourage the idea that a suntan is both healthy and desirable. Accordingly, suntanned skin can promote a sense of psychological well-being. As a consequence, despite current health education concerning the dangerous effects of ultraviolet light, sunbathing – in either natural or artificial sunlight – remains a popular pastime. Naidoo & Wills (2005) recognize the challenges for health promoters in that the message to reduce exposure to sunlight is at odds with lay beliefs that sunlight is beneficial. It is necessary to address the conflict between the improvement to psychological health and its detrimental effect on an individual’s physical health. Gross (2005: 418) examines Festinger’s theory of cognitive dissonance. Cognitive dissonance is a state of ‘psychological discomfort and tension’ caused by a person knowing that an action may cause harm, but at the same time participating in that action. Festinger’s theory can be useful for choosing between two activities that are equally attractive. This involves highlighting the undesirable features of each activity in order to help with the decision making process. Although this may help in deciding whether or not to sunbathe, it must be acknowledged that an individual may still decide that the psychological benefits of sunbathing are more important and therefore continue the activity.

These are used to accentuate attractive facial features and disguise imperfections. Cosmetics can have religious or cultural significance; for example, the bindhi is traditionally a red or maroon dot worn on the forehead of Hindu women. It is customarily worn by married women to symbolize their marriage and myth is that it protects them from the ‘bad eye’ of people (Mehta Products 2007).

These are a form of tattooing where patterns are cut directly into the skin. They often hold religious significance or show membership of a particular tribe or group. They are deemed to be an essential feature of some cultures and are considered attractive in both males and females.

There has been a huge increase in the popularity of body piercing. Ears, nose, navel, eyebrows and nipples have all been subject to this trend and have become fashion statements, particularly among teenagers and young adults

Skin adornments, particularly tattoos and body piercing, have implications for healthcare workers (see Evolve 15.2).

Skin colour varies between individuals, most obviously between people of different ethnic origins. There are several aspects of wound assessment and management that need to be addressed for patients with darkly pigmented skin (see Annotated Further Reading: Bethell 2005). There are also differences in skin colour in different parts of the body of each individual. Nipples and areolae of the breasts are darker than the rest of the skin, particularly in women during pregnancy. Similarly, areas that are exposed to sunlight, such as the face and arms, tend to be darker due to increased melanin concentration. These differences aside, and with the exception of older people in whom pigmentation can increase unevenly, skin colour is usually uniform.

An assessment of skin colour involves examining areas that are not generally exposed to sunlight, such as the palm of the hand. For the first few days of life the hands and feet of newborn babies are a bluish colour, termed acrocyanosis, due to inadequate peripheral vasculature. Assessment thereafter should involve looking for specific changes in skin colour, for instance:

These changes in colour are most obvious in certain parts of the body. Cyanosis and pallor are particularly evident at the nail beds and buccal (mouth) mucosa. It is especially important to look at these areas in dark-skinned clients, as changes in general skin colour are less evident. Asian children may have Mongolian blue spots, which are very common and normal. The nurse should note any bruising. Although bruising can be normal, extensive or fingertip-type bruising can be a sign of abuse and should be investigated further, following agreed protocols.

Feeling the client’s skin with the back of your hand best assesses skin temperature. The temperature of the skin increases or decreases with an increase or decrease in the circulation of blood through the dermis. Hands and feet are normally colder than the rest of the body when exposed to a cold environment due to reduced peripheral blood flow. Localized areas of increased or decreased temperature may indicate a problem. Hot, inflamed, red and painful skin surrounding a wound indicates the presence of infection. Similarly, if an unexposed limb is cold and pale, there may be circulatory impairment. When clients have had vascular surgery or a plaster cast or bandages applied to a limb, it is important to assess for skin changes that indicate impaired blood flow.

Moisture refers to the wetness and oiliness of skin. It is related to the level of hydration and general condition of the skin. Normally the skin is smooth and dry except in the folds of the skin where it is moist. An increase in skin temperature arising from a hot environment or exercise is accompanied by perspiration, and is a normal phenomenon. However, when a client has a fever resulting from, for example, an infection, the skin may initially feel dry and hot but become damp from perspiration as the fever breaks. In older people dry skin, which is often accompanied by itchiness, can be a problem.

Usually the skin is smooth, soft and flexible, although in older people it sometimes becomes wrinkled and leathery. Skin thickness varies in different parts of the body: for example, skin is thickest on the palms of the hands and soles of the feet. Assess skin texture by stroking and palpating the skin with the fingertips; the nurse can gauge smoothness, thickness, suppleness and softness. Localized areas of changes to skin texture may indicate previous trauma or lesions. Should such changes be apparent, the nurse should ask the client about them. Rough and dry skin can also be due to exposure to cold weather or overwashing.

Turgor refers to the elasticity of the skin, which is normally elastic and taut. It can be assessed by gentle pinching, lifting and letting go of an area of skin, usually on the back of the hand. Normally, the skin should quickly return to its former position. If it does not, it indicates that the client is dehydrated. However, some loss of skin elasticity is normal in older individuals. Excessive accumulation of fluid in the tissue – termed oedema – gives the skin a taut shiny appearance. It results from either direct trauma to the skin or an underlying condition. The presence of oedema increases susceptibility to further skin damage and delays wound healing.

Many skin blemishes and lesions are normal, for instance birthmarks, moles and freckles, and minor cuts, abrasions and blisters. Equally, nappy rash and heat rash are common among babies and children and mild acne is not uncommon in adults. Other blemishes and lesions, however, require further investigation and it may be necessary to refer the client to a doctor. For example, changes in an existing mole may indicate the development of a malignant melanoma.

Rashes may be caused by infection, such as a postviral rash, chickenpox, meningitis and shingles, or an allergic response, for example to particular chemicals, food products or medication. Other lesions may arise from skin infestations such as scabies, as a result of accidental or intentional trauma to the skin, or as a result of skin disease such as psoriasis or eczema (see Evolve 15.3). When abnormal blemishes, including scars or lesions, are detected, their colour, size, location and specific characteristics and, where appropriate, distribution and grouping should be noted. Clients should be asked about such blemishes, in particular to determine their cause.