The skin acts as an interface between the internal milieu and the environment and provides many functions essential for human survival, including:
• | Modulation of transepidermal water fluxes, protection from dehydration and excessive water influx, and maintenance of electrolyte homeostasis |
• | Thermoregulation and minimization of caloric losses |
• | Antimicrobial defense |
• | Protection from environmental toxins |
• | Protection from trauma |
• | Protection from ultraviolet radiation |
• | Tactile sensation |
Cliccare qui per andare alla sezione Riferimenti The barrier typically forms in utero during the third trimester. Developmental immaturity of the permeability barrier may include: • | Structural immaturity • | Stratum corneum and epidermis are thinner than in term infants. | • | Anchoring fibrils, anchoring filaments, and hemidesmosomes are fewer and smaller than in term infants, leading to decreased anchoring of the epidermis and increased susceptibility to shear forces. | |
• | Stratum corneum epidermal permeability barrier is underdeveloped, leading to increased transepidermal water loss, loss of heat, increased caloric demands, increased potential for absorption of environmental toxins, and compromised antimicrobial defense. |
• | Expression of cationic antimicrobial peptides may be developmentally decreased. |
• | Antibacterial acid mantle forms more slowly in neonates weighing less than 1 kg than in larger, more mature neonates. |
• | Formation of a protective layer of vernix is underdeveloped. |
• | Decreased numbers of melanocytes with immature melanosomes leads to increased susceptibility to ultraviolet light–induced damage. |
• | A reduced subcutaneous fat supply limits thermoregulatory capabilities and buffering capacity against redistribution of fat-soluble drugs. |
Cliccare qui per andare alla sezione Riferimenti to be 10-fold to 15-fold greater in premature infants of 25 weeks' gestation compared with full-term infants.70 Hammarlund K., Sedin G. Transepidermal water loss in newborn infants: III. Relation to gestational age Acta Paediatr Scand 1979 ; 68 : 795-801
Cliccare qui per andare alla sezione Riferimenti This may result in fluid losses of as much as 30% of total body weight in 24 hours and may be associated with: • | Significant morbidity caused by dehydration and hypotension, increasing the risk for intraventricular hemorrhage and, possibly, necrotizing enterocolitis |
• | Electrolyte imbalance, especially hyperosmolar hypernatremia, which also may place neonates at increased risk for intraventricular hemorrhage |
• | Thermal instability |
• | Increased caloric demands because skin evaporative losses (580 calories/mL) may comprise as much as 20% of the total energy expenditure of preterm infants born at less than 30 weeks' gestational age |
Another critical function of the skin is antimicrobial defenses, which include:
• | Stratum corneum: xeric environment, acidic pH (i.e., “acid mantle”), antimicrobial lipids (e.g., oleic acid, sphingosine, sphinganine, hydroxysphinganine; possibly serine protease activity of cholesterol sulfate), continual shedding of corneocytes |
• | Cationic antimicrobial peptides: skin-derived antileukoprotease (elafin), secretory leukocyte protease inhibitor (SLPI; antileukoprotease), human β-defensin-2, LL-37 |
• | Cytokines: interleukin (IL)-1⍺, IL-1β, tumor necrosis factor-⍺, IL-10, and IL-12 |
• | Granzyme B |
• | Fas ligand |
• | Nitric oxide |
• | Resident cutaneous flora (e.g., bacterial interference or bacteriocins) (not part of the innate immune system, but defense is intrinsic to the skin) |
Cliccare qui per andare alla sezione Riferimenti, 121 Miller S.J., Aly R., Shinefield H.R. , e al. In vitro and in vivo antistaphylococcal activity of human stratum corneum lipids Arch Dermatol 1988 ; 124 : 209-215
Cliccare qui per andare alla sezione Riferimenti Neonates, especially preterm infants, are at high risk for infection, however, because of epidermal barrier immaturity; developmental defects in systemic immune function; and, possibly, disordered cutaneous immunoregulatory function in association with barrier perturbation or decreased cationic antimicrobial peptide expression.126 Nickoloff B.J., Naidu Y. Perturbation of epidermal barrier function correlates with initiation of cytokine cascade in human skin J Amer Acad Dermatol 1994 ; 31 : 535-546 [cross-ref]
Cliccare qui per andare alla sezione Riferimenti, 127 Nishijima T., Tokura Y., Imokawa G. , e al. Altered permeability and disordered cutaneous immunoregulatory function in mice with acute barrier disruption J Invest Dermatol 1997 ; 109 : 175-182
Cliccare qui per andare alla sezione Riferimenti As a result, infectious diseases and prematurity, together with birth asphyxia, are the major causes of neonatal deaths worldwide. Approximately one fourth of all very low birth weight (VLBW) infants weighing less than 1.5 kg in the United States who survive beyond the third day of life have at least one episode of sepsis.165 Stoll B.J., Gordon T., Korones S.B. , e al. Late-onset sepsis in very low birth weight neonates: A report from the National Institute of Child Health and Human Development Neonatal Research Network J Pediatr 1996 ; 129 : 63-71 [cross-ref]
Cliccare qui per andare alla sezione Riferimenti In developing countries, the prevalence of sepsis in premature infants is estimated at 30% to 60%, and the mortality rate is 40% to 70%; septicemia is the most prevalent cause of death, accounting for as much as 50% of neonatal mortality in premature infants.13 Bartlett A.V., Paz de Bocaletti M.E., Bocaletti M.A. Neonatal and early postneonatal morbidity and mortality in a rural Guatemalan community: The importance of infectious diseases and their management Pediatr Infect Dis J 1991 ; 10 : 752-757 [cross-ref]
Cliccare qui per andare alla sezione Riferimenti, 164 Stoll B.J. The global impact of neonatal infection Clin Perinatol 1997 ; 24 : 1-21
Cliccare qui per andare alla sezione Riferimenti Globally, an estimated 350,000 of neonates die each year because of septicemia and meningitis164 Stoll B.J. The global impact of neonatal infection Clin Perinatol 1997 ; 24 : 1-21
Cliccare qui per andare alla sezione Riferimenti; approximately half of these deaths occur in the first week of life, when epidermal barrier function is most highly compromised.Postnatal age and gestational age are important considerations in assessing skin maturity and in determining skin-care practices because exposure of premature skin following birth to the dry, extrauterine environment accelerates development of an effective epidermal barrier.71 Hanley K., Jiang Y., Elias P.M. , e al. Acceleration of barrier ontogenesis in vitro through air exposure Pediatr Res 1997 ; 41 : 293-299
Cliccare qui per andare alla sezione Riferimenti, 74 Harpin V.A., Rutter N. Barrier properties of the newborn infant’s skin J Pediatr 1983 ; 102 : 419-425 [cross-ref]
Cliccare qui per andare alla sezione Riferimenti, 183 Williams M.L., Hanley K., Elias P.M. , e al. Ontogeny of the epidermal permeability barrier Journal of Investigative Dermatology Symposium Proceedings 1998 ; 3 : 75-79
Cliccare qui per andare alla sezione Riferimenti Barrier maturation following premature birth, however, typically requires approximately 2 to 4 weeks and may require as long as 8 weeks in extremely premature infants.74 Harpin V.A., Rutter N. Barrier properties of the newborn infant’s skin J Pediatr 1983 ; 102 : 419-425 [cross-ref]
Cliccare qui per andare alla sezione Riferimenti, 88 Kalia Y.N., Nonato L.B., Lund C.H. , e al. Development of skin barrier function in preterm infants J Invest Dermatol 1998 ; 111 : 320-326 [cross-ref]
Cliccare qui per andare alla sezione Riferimenti This suggests that, as more preterm infants survive at earlier gestational ages that approach the limits for interfollicular cornification and stratum corneum maturation at 22 to 24 weeks' gestational age, the stratum corneum responds more slowly to maturational signals expressed after birth.73 Hardman M.J., Moore L., Ferguson M.W.J. , e al. Barrier formation in the human fetus is patterned J Invest Dermatol 1999 ; 113 : 1106-1113 [cross-ref]
Cliccare qui per andare alla sezione Riferimenti, 182 Williams ML: Skin of the premature infant. In Eichenfield LF, Frieden IJ, Esterly NB (eds): Textbook of Neonatal Dermatology. Philadelphia, WB Saunders, in press
Cliccare qui per andare alla sezione Riferimenti During the neonatal period, although barrier function is developing, premature infants suffer significant morbidity and mortality, especially during the first week of life, when approximately two thirds of neonatal deaths occur.90 Kelley L Black RE Interventions to reduce neonatal mortality: Implications for programs and research. Proceedings of the Conference of the US Child Health Research Project (USAID)Baltimore, May 10–12, 1999
Cliccare qui per andare alla sezione Riferimenti
The importance of neonatal skin care is exemplified by survey results suggesting that nearly 80% of newborns develop a skin problem (i.e., “rash”) during the first month of life.42References 62,65,95,96,97,106,109,112,120 and 154.
Cliccare qui per andare alla sezione Riferimenti But little information is available on which a rational approach to skin care in neonates may be based, and few instructions or recommendations for neonatal skin care are available in the literature.*References 62,65,95,96,97,106,109,112,120 and 154. This article reviews fundamental care and hygiene of neonatal skin, with particular reference to preterm infants born at less than 33 weeks' gestational age and hospitalized neonates who require intensive care, in whom these activities are of vital importance. Strategies for optimizing epidermal barrier integrity, including bathing and emolliation practices, preventing and managing infections and skin injury, and minimizing TEWL and heat or percutaneous absorption of toxins, are emphasized.
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W. B. Saunders Company. Pubblicato da Elsevier Masson SAS. Tutti i diritti riservati.
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