51 The skin is the largest organ in the body, responsible for 20% of its total weight and, together with the hair, nails and glands, it forms the integumentary system. The main function is protection, because skin can prevent environmental agents from causing harm, conserve fluids, assist with thermoregulation, participate in the production of vitamin D (required for the absorption of calcium and phosphate by the small intestine) and relay important information to the brain via touch and pressure. Three distinct layers of the skin exist: the epidermis, the deeper dermis and the hypodermis or subcutaneous layer of connective tissue (Figure 51.1). Skin integrity may be threatened by both intrinsic factors (related to the patient’s condition) and extrinsic factors (originating from external sources) and a recognised risk assessment tool such as the Waterlow score should be used to determine if these are present.1 Some patients are predisposed to skin impairment owing to the general state of their health and the pre-existence of medical disorders such as diabetes mellitus. Secondly, the skin of elderly patients will already be susceptible to breaking down, independent of any ill health. This is because there are many changes naturally occurring in skin as part of the ageing process (Figure 51.2). Finally, inadequate nutrition is a significant risk factor for impaired skin integrity (Chapter 52). An inability to meet dietary requirements can lead to loss of skin collagen and moisture, which in turn can cause wounds and delay healing.
Skin integrity
Skin: function and structure
Factors impairing skin integrity in acute illness
Poor perfusion