Nurses have a primary role in the assessment and treatment of dry skin. Understanding the structure and function of the skin, the variables associated with dry skin, and the researchbased approaches used to treat dry skin enhances the ability of the nurse to intervene appropriately. Through such interventions, the discomfort and complications that accompany the phenomena of dry skin can be avoided.
Skin is the largest organ in the body. It consists of two layers, an outer epidermis and an inner dermis, which is anchored by connective tissue to underlying muscle or bone. The skin serves as a protective barrier against penetration from chemicals and microorganisms, regulates core body temperature, and minimizes loss of water and plasma proteins (Steinbaugh, 1983).
The epidermal layer arises from a single layer of cells, the basal cells. The basal cells produce keratinocytes, which differentiate as they approach the skin surface. As this process continues, these cells elongate and flatten, and their membranes become thick (Steinbaugh, 1983).
The final step in cell differentiation is the production of the stratum comeum, the outermost layer of the epidermis. The stratum corneum is most responsible for the epidermal water/protective barrier (Downing, 1987; Steinbaugh, 1983). The inside the stratum corneum cells are filled with keratin, which is a durable protein, and they are joined by complex lipid bilayers (Spencer, 1988). The stratum corneum lipids mainly consist of ceramides, sterols, and free fatty acids (Blanken, 1989).
Water molecules, which diffuse from the vasculature of the underlying tissues, are added to the intercellular protein-lipid matrix (Dotz, 1983). These "secondary molecules" are weakly attached to primary water molecules, which are tightly bound to groups of structural proteins within the stratum corneum (Takenouchi, 1986). Secondary water molecules induce suppleness in the stratum corneum when its content exceeds 10% (Strianse, 1978; Takenouchi, 1986).
Water-soluble substances in the normal stratum corneum, known collectively as a natural moisturizing factor, also have been suggested to play an important role in the hygroscopicity of the stratum corneum (Takenouchi, 1986). Sebum, which is secreted by the sebaceous glands, maintains skin hydration by providing a protective lipid layer that minimizes fluid loss through the epidermis.
Dry skin is the loss of moisture from the stratum corneum or intercellular matrix. This loss of moisture results in an outer stratum corneum layer that is mechanically less pliable (Spencer, 1988). Loss of surface or intercellular lipids also may produce a mechanically less pliable outer stratum corneum. The decrease in pliability results in cracking and alteration of the outer layer. Normal flexing of damaged, less pliable skin increases scaling and cracking. Roughness and scaling are associated with increases in transepidermal water loss, due to a defective water barrier and reservoir function in the stratum corneum (Thune, 1988).
The characteristics of dry skin have been described in the nursing and medical literature. Although reported characteristics often are similar, they have not been validated through research. Clinically, dry skin appears rough, uneven, and cracked. Raised or uplifted skin edges (scaling), desquamation (flaking), chapping, and pruritus may be present (Parent, 1985). Extremely problematic cases may include Assuring, inflammation, and erythema (Parent, 1985). Although the underlying mechanism responsible for dry skin is unknown, the presence of any or all these characteristics indicates the need to assess contributing factors involved, and to intervene appropriately.
Factors purported to contribute to the occurrence of dry skin have been enumerated in the health care literature. Of primary importance in the elderly population are the changes in the skin that accompany aging. A flattening of the dermal-epidermal junction and an increase in keratin cross-linking lessens skin flexibility (Montagna, 1979; Steinbaugh, 1983). A loss of dermal blood vessels and a thinning of collagen fibrils in the dermis may shift the water content of the skin (Kligman, 1979, 1985). Furthermore, a decrease in the rate of epidermal cell turnover and reduced natural water and fat emulsions on the skin may modify the epidermal water/protective barrier. These changes in the skin of the aging individual may put him or her at additional risk for dry skin.
Other factors contributing to dry skin that have been discussed in the literature are the many variables associated with bathing. Although excessive bathing has been reported to contribute to dry skin, no research has demonstrated this relation. The use of soaps, which reduce the pH of the skin and remove natural skin oils, also may be a contributing factor to dry skin (Steinbaugh, 1983). Frosch and Kligman (1979) suggested that soap has its impact on the stratum corneum, which is attacked by the anionic surfactants of the soap. This situation leads to tissue damage characterized as chapping. In addition, household detergents remove intercellular lipids and may contribute to the phenomenon of dry skin (Strianse, 1978).
The lack of environmental humidity also has been suggested to contribute to dry skin. Air conditioning during the summer and heating systems in the winter produce low humidity environments. Relative humidities of 30% to 60% have been suggested as necessary to maintain adequate hydration (Blank, 1952; Dotz, 1983; Spencer, 1988; Witkowski, 1980).
Other researchers have suggested that the symptoms of dryness, scaling, cracking, and itching are associated with a reduction of humidity below these levels (Dotz, 1983; Kligman, 1978). Although adequate levels of environmental humidity are thought to be necessary to maintain stratum corneum hydration, it is not entirely clear whether the clinical symptoms of dry skin are always associated with lower levels of stratum corneum hydration.
Additional factors that have been cited in the literature as being related to the presence of dry skin are systemic dehydration, exposure to the sun, smoking, stress, and excessive perspiration (Atkins, 1977; Cornell, 1986; Fitzsimmons, 1983; Spencer, 1988). The role of nutrition in dry skin is unclear. Dry skin has been associated with essential fatty acid deficit; however, no association between dry skin and nutrition was found by Frantz and Kinney (1986).
MANAGEMENT OF DRY SKIN
Management of dry skin is directed toward controlling environmental variables and minimizing the signs and symptoms associated with its occurrence. Although adhering to the following principles will not correct the basic defect that underlies the development of dry skin, a treatment plan that is guided by these considerations will add significantly to the patient's comfort.
Lack of Moisture in the Air
A major environmental variable to address in controlling dry skin is lack of moisture in the air. Low relative humidities are especially prevalent in overheated homes and buildings, regrettably the preferred standard among many elders. In order to reduce the effects of dry environmental conditions, efforts should be directed at adding moisture to the air through humidification. Freestanding room humidifiers or central humidifiers interfaced to the heating system can significantly reduce the detrimental effects of low relative humidities on the stratum corneum.
Soaps and Cleansers
Dry skin can be managed further by reducing the use of soaps and cleansers. Soaps contain synthetic surfactants and salts of fatty acids that have been shown to produce discernible levels of irritancy - ranging from slight redness to scaling and even fissuring. Interestingly, the soaps touted by manufacturers as mild do not endure in controlled studies of irritancy.
Frosch and Kligman (1979) tested the irritancy level of 18 brand name soaps on 20 healthy subjects. They found that Dove synthetic detergent bar far exceeded all others tested for lowest level of irritancy. Zest, Camay, and Lava were notable for their high irritancy levels. Furthermore, several soaps that are frequently recommended for their mildness were found to be moderately irritating, including Ivory, Neutrogena, and Lubriderm.
The value of superfatted soaps, believed to be milder because of a "protective" film of oil they leave on the skin, was not supported by this study. Because soaps emulsify and remove oils, superfatting is of dubious value. Therefore, the use of soaps in individuals with dry skin should be limited to perineal and axillary regions. In addition, care should be taken to select a soap with a documented low irritancy level.
Another environmental variable associated with dry skin that is closely related to the use of soaps and cleansers is the frequency of bathing. Reducing the frequency of bathing often is suggested as an approach to controlling dry skin. There is no research or clear recommendations from experts, however, regarding the appropriate frequency for bathing, or whether showers or tub baths are more helpful in controlling dry skin.
Controlling the signs and symptoms of dry skin can be accomplished by applying any of a variety of topical agents that are known collectively as moisturizers. The most effective moisturizer is petrolatum. Although its aesthetic characteristics are somewhat undesirable, research has demonstrated that twice daily applications of petrolatum completely obliterated skin dryness in 3 weeks and this state persisted for at least 3 weeks after treatment ceased (Kligman, 1978). More recent studies of petrolatum's effects have demonstrated that it permeates throughout the interstices of the stratum corneum, forming an occlusive layer on the outer surface while allowing normal barrier recovery (Ghadially, 1992). Thus, it may not only reduce water loss from the epidermis, but also provide a high degree of protection from injury.
Preparations marketed for their moisturizing properties are available as ointments, creams, or lotions. Ointments are mixtures of water in oil, with the typical oil component being either lanolin or petrolatum. Examples of lanolin-based products are Nivea, Eucerin, and Keri; petrolatum-based products include Unibase and Hydrophilic Petrolatum USP.
These formulations are distinguished by their occlusive character, which enhances their effectiveness in mamtaining moisture in contact with the skin. Although these formulations have not been systematically compared in controlled studies, Kligman (1978) reported more effective resolution of dry skin manifestations with petrolatum than lanolin.
Creams are preparations of oil in water, with the main component being water, which renders them less viscous and more aesthetically acceptable. Examples of over-thecounter creams are Keri Cream, Lubriderm, Cold Cream USP, Hydrophilic Ointment USP, and Vaseline Dermatology Formula.
Creams are less occlusive than ointments and so they must be applied more frequently (at least four times a day) in order to maximize their effectiveness. Lotions are composed of powder crystals dissolved in water and held in suspension by any of a number of surface active agents. As a result of the high water content, lotions have a coolant effect on the skin and do not leave the skin feeling greasy. Among some of the widely available lotions are Aloe Vera, Esoterica Dry Skin, Eucerin, Vaseline Intensive Care, and Alpha Keri.
Although lotions are easy to apply and are aesthetically more pleasing than ointments and creams, they do not possess the same occlusive characteristics. Therefore, frequent applications may be necessary to relieve the signs and symptoms of dryness, and even then the effect will be transient.
The practice of adding oil to bath water has been advocated by some practitioners as a means of controlling dry skin. However, a comparative study of skin hydration following bath oil and tap water baths showed no difference in performance levels (Stender, 1990). The increase in water-holding capacity of the skin as a result of the bath oil was slight and of no real importance to skin surface hydration.
Although there was no real improvement in epidermal hydration from the bath oil, changes in the epidermis were observed that were analogous to those observed after a single application of a moisturizer. Thus, it appears that use of bath oil acts as a moisturizing lotion spread over the entire body surface. Because the moisturizing effect of bath oil is temporary (as with lotions), frequently repeated oil baths would be necessary to obtain the same effect as repeated applications of lotion. Using moisturizers to control the manifestations of skin dryness is clearly the more practical approach.
Because the mechanisms that underlie dry skin have not been fully elucidated, treatment is necessarily directed toward controlling the signs and symptoms. Given the current state of knowledge, the primary element in any approach to treating dry skin is moisturizers. Although no moisturizer can be considered completely ineffective if one is satisfied with immediate benefits, the challenge is differentiating those that provide only temporary masking effects from those that bring about an enduring physiologic change. By insisting on data that document efficacy, health care providers can advance the development of formulations with true biological effects that last.
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