The dermis is made of collagen and elastin fibers in a gel matrix, providing mechanical strength, protection, and elasticity to the skin. The dermis of the term newborn is thinner than the adult dermis and has a higher water content. ^56,73 Collagen deposition in the dermis increases with advancing gestational age, preventing fluid from accumulating in this layer. Premature infants have a tendency to become edematous, because they have less collagen and fewer elastin fibers in the dermis.

Numerous fibrils connect the epidermis to the dermis at the dermo-epidermal junction. These fibrils are more widely spaced and fewer in number in the premature infant⁵⁶ (Figure 19-3) but become stronger with advancing gestational and postnatal age. Genetically abnormal fibrils at this junction are found in certain types of the genetic disorder epidermolysis bullosa, a blistering skin condition that occurs with even minimal trauma. Premature infants also are prone to blistering from injury, although this decreases as they mature. This diminished cohesion places premature infants at risk for injury from adhesive removal as well. Particularly if extremely aggressive adhesives are used, there may be a stronger bond of the adhesive to the epidermis than of the epidermis to the dermis, and epidermal stripping may result during adhesive removal.

The ability of the skin surface to form and maintain an acid surface is a function of various chemical and biologic processes. Acid skin surfaces with a pH less than 5 have been documented extensively in adults and children. ¹³ This acid mantle has protective qualities against some pathogens and other microorganisms. Because microbial colonization begins with delivery, the acid skin surface helps keep a state of equilibrium; if the pH shifts from acidic to neutral, there may be an increase in total numbers of bacteria and a shift in species. TEWL also may increase when skin pH rises. ¹²²

Term newborns are born with a relatively alkaline skin surface, measuring a mean pH of 6.34. Within 4 days, the pH declines to a mean of 4.95. ¹³ Skin pH measurements have been reported in premature infants of varying gestational ages, and the pH was above 6 on the first day, decreasing to 5.5 during the first week, and gradually declining to 5 during the first month. ⁴³Bathing and other skin care practices alter skin pH; it may take an hour or longer to regenerate the acid mantle after bathing with an alkaline soap. Skin that is occluded by wearing diapers has been shown to have a pH of 6, which is known to be a risk factor in the development of diaper dermatitis. ¹²¹

Fat and zinc accumulate in the fetus during the last trimester of pregnancy. Because these nutritional components are necessary for maintaining an intact, healthy skin surface, premature infants born before the last trimester may develop skin problems caused by deficiencies in either of these nutrients. Problems also may be seen in infants who are unable to receive adequate enteral nutrition unless appropriate parenteral supplements are employed.

Essential fatty acid (EFA) deficiency can be seen in premature and postmature infants because of decreased fat stores (see Chapter 17). In this condition, there is a superficial scaling and occasionally desquamation and irritation in the neck, groin, or perianal area. There may be decreased serum levels of EFAs, thrombocytopenia, and impaired platelet aggregation because EFAs are needed to promote platelet function. ⁴⁴

Providing adequate EFA prevents skin manifestations of EFA deficiency. In infants who are receiving small amounts of enteral nutrients or none at all, administration of intravenous (IV) lipid solutions at a total dose of 0.5 g/kg/day can prevent EFA deficiency (see Chapter 16). Once EFA deficiency occurs, IV lipids can reverse the process in 1 to 2 weeks. Dietary replacement takes longer and is effective only if gastrointestinal function is good. Topical therapy with sunflower seed oil, which is rich in linoleic acid, promotes transdermal absorption of EFA and raises serum levels but is variable in the rate of absorption. In a study of topical application, researchers found that safflower oil failed to yield improvements in patients with EFA deficiency. ⁵⁷

Zinc, an essential trace mineral, is a cofactor in many areas of metabolism, including lymphocyte transformation and metabolism of protein, nucleic acids, and mucopolysaccharides of skin and subcutaneous tissues and is necessary for normal wound healing. ³⁵ Two thirds of the transfer of zinc from mother to fetus occurs in the last 10 weeks of pregnancy. Zinc deficiency occurs when there are abnormal losses of zinc in stool or urine; when there are low or absent stores, as in premature birth; or during increased demands, such as during rapid growth, stress, or tissue healing. Thus premature infants and infants with pathologic conditions of the intestine (including chronic diarrhea, short bowel syndrome, intestinal diversions such as ileostomy, or intestinal resection) are at increased risk for zinc deficiency. In addition, any infant receiving total parenteral nutrition should receive trace minerals to prevent zinc deficiency (seeChapter 16).

Among the purposes of bathing the newborn are overall hygiene, aesthetics, and protection of health care workers by removing blood and body fluids. Bathing, however, is not an innocuous procedure. During the immediate postbirth period, bathing can result in hypothermia, increased oxygen consumption, and respiratory distress. To prevent hypothermia, increased oxygen consumption, and respiratory distress, the first bath should be delayed until the infant’s temperature has been stabilized in the normal range for 2 to 4 hours⁹⁵or at 1 hour if radiant heat is provided during the bath.¹¹⁶ With appropriate attention to the environment, there is no difference in heat loss when the bath is performed at the bedside in the mother’s room or in the nursery. ⁸⁷Bathing also has been shown to destabilize vital signs and temperature in premature infants.⁹⁶

Bathing with antiseptic soaps and cleansers is still practiced in some nurseries. Studies have shown that although hexachlorophene reduced the number of Staphylococcus aureus strains present on the skin, toxicity was reported, especially in premature infants, associated with absorption through the skin; it should not be used. ^3,67,104 Both povidone-iodine and chlorhexidine are sometimes used for the initial bath in newborn nurseries, although the effect on bacterial colonization is transient. ³²Chlorhexidine has proved effective in reducing colonization for up to 4 hours³²but also can be absorbed.³¹ Although toxicity from chlorhexidine has not been identified, many nurseries do not use it for routine bathing because of the potential risk. Antimicrobial soap is not recommended by the American Academy of Pediatrics and the American College of Obstetricians and Gynecologists⁴ because of the harshness of the soap and the potentially negative effect it may have on normal skin colonization.

Soaps made with lye and animal fats are alkaline, with a pH above 7.0. Cleansing bars and liquids made with synthetic detergents are formulated to a more neutral pH of 5.5 to 7.0. All soaps and cleansers are at least mildly irritating and drying to skin surfaces^114,115and disrupt the skin surface pH.⁴⁸ In addition, the degree to which the skin is irritated also depends on the length of contact and the frequency of bathing.

The recommendations are (1) to select cleansers that have a neutral pH and minimal dyes and perfumes to reduce risk for potential sensitization to these products, and (2) to bathe the infant no more than every other day.⁷ The effects of bathing on skin parameters in small premature infants have not been studied to date. To reduce alterations in skin pH, dryness, and irritation in premature infants less than 32 weeks, cleanse with warm-water baths during the first week, using soft cotton cloths, cotton balls, or the caregiver’s hands. It has been shown that skin colonization with bacteria does not increase with bathing as infrequently as every 4 days.⁹⁸ Less frequent bathing may offer other advantages for premature infants, who have demonstrated physiologic and behavioral disruptions during sponge baths. ⁹⁶ Immersion bathing, even of stable infants on ventilators or nasal continuous positive airway pressure (NCPAP), may be soothing and less stressful. ²

Immersion bathing places the infant’s entire body, except the head and neck, into warm water (38 ° C [100.4 ° F]), deep enough to cover the shoulders. A recent study of immersion versus sponge bathing in 102 newborns for their first and subsequent baths showed that the immersion-bathed infants had significantly less temperature drop and appeared more content and their mothers reported more pleasure with the bath; there was no difference in cord healing scores with either immersion or sponge bathing. ¹⁹ Immersion bathing is also beneficial from a developmental perspective. ^2,5 Stable premature infants after umbilical catheters are removed and term infants with umbilical clamps in place can be bathed safely in this way. ⁷Bathing is an excellent time to educate parents (1) about how to physically care for their baby and (2) about their baby’s neurobehavioral status and social characteristics.⁶⁴

The skin surface of term newborns is drier than that of adults but becomes gradually better hydrated as the eccrine sweat glands mature during the first year of life. ^90,103 Maintaining the hydration of the stratum corneum is necessary for an intact skin surface and normal barrier function. Skin that is dry, scaly, or cracking not only is uncomfortable but also can be a portal of entry for microorganisms. Products used to counteract dryness are called moisturizers, emollients, or lubricants. Common emollients include mineral oils, petrolatum, and lanolin and its derivatives. Emollients are sometimes divided into oil-in-water or water-in-oil emulsions.

Emollient use to prevent dermatitis and improve skin integrity has been studied in several randomized, controlled trials in premature infants. In one report, ⁶⁸ premature infants of 29 to 36 weeks’ gestation were treated with Eucerin cream daily and had less dermatitis as measured by a visual grading scale but no differences in direct measurements of TEWL with an evaporimeter. In a later study, premature infants of both shorter gestation and younger postnatal age were treated with Aquaphor ointment, a water-miscible oil-in-water preparation that contains neither dyes nor perfumes. In this study, there was improvement in both TEWL and visual scale dermatitis. No increases in skin surface temperatures or thermal burns were seen, even when the emollient was applied to infants under radiant heaters or phototherapy lights. In addition, cutaneous cultures revealed no increase in bacterial or fungal colonization on skin treated with emollients. It was noted that fewer treated infants had positive blood or cerebrospinal fluid culture results compared with control subjects, although the study was not large enough to prove this effect. ⁹³

A large, randomized controlled trial of 1191 infants with birth weights of 501 to 1000 g was conducted to determine whether twice-daily application of Aquaphor ointment would reduce combined outcome measures of mortality and sepsis. Although skin integrity appeared improved with routine emollient use, no effect was seen in the outcomes of sepsis plus mortality. Of note, an increase in coagulase-negative Staphylococcus epidermidis bloodstream infections was seen in infants with birth weights below 750 g, although the mechanism and relationship to emollient use are not clearly understood. ⁴⁰ Although a small case-control study had previously associated petrolatum-based emollients with a higher incidence of fungal infections, ²² this was not seen in the larger trial. The effects of emollients on TEWL or fluid balance were not studied in this trial.

The benefits of emollient use must be carefully weighed against the risk for infection. In general, emollients can be safely used to treat skin with excessive dryness, cracking, or fissures on an “as-needed” basis. They also may be effective in reducing TEWL and evaporative heat loss, although other methods, such as using a high-humidity environment or transparent adhesive dressings, also are available for this purpose. Avoiding products with perfumes or dyes is prudent, because these can be absorbed and are potential contact irritants. ²⁶Small tubes or jars for single-patient use are recommended to prevent contamination with microorganisms.

Decontamination of skin before invasive procedures such as venipuncture and placement of umbilical catheters and chest tubes is common practice in neonatal intensive care nurseries. However, there are anecdotal reports of skin injury, including blistering, burns, and sloughing, from disinfectants including isopropyl alcohol, povidone-iodine, and alcohol-containing chlorhexidine use in premature infants.^51,101,105 There have been case reports of high iodine levels, iodine goiter, and hypothyroidism associated with povidone-iodine use in premature infants. ^27,60,97 Several prospective studies of routine povidone-iodine use in intensive care nurseries^70,94,107 and one study of presurgical skin preparation of infants younger than 3 months⁸⁹ found alterations in iodine levels and thyroid effects from povidone-iodine exposure as a result of absorption through the skin. Although one study did not find alterations in thyroid function from iodine absorption in neonates, ⁴⁹ the study period (10 days) may be too short to see this effect.

Another important aspect of skin disinfection is how effectively disinfectant solutions reduce colonization and infection rates. During skin preparation before blood culture sampling in children and adults, lower rates of microbial colonization were seen with povidone-iodine compared with isopropyl alcohol.³⁰ A larger study of blood culture sampling in adults found fewer contaminated cultures when chlorhexidine had been used compared with cultures from povidone-iodine–cleansed subjects.⁸⁸

Two studies in premature infants compared skin and peripheral intravenous catheter colonization with bacteria after skin preparation with either chlorhexidine or povidone-iodine. Malathi et al⁸² found the rate of colonization was no different between disinfectants but the technique of application was important: the authors recommended longer periods of cleansing (>30 seconds) or two consecutive cleansings for maximum reduction of colonization. Garland et al⁴⁵ reported that chlorhexidine reduced catheter colonization: 4.3% with chlorhexidine compared with 9.3% with povidone-iodine.

A meta-analysis of eight studies involving 4143 central catheters in adult patients found that using chlorhexidine gluconate–containing disinfectants for insertion and routine site care reduced the risk for catheter-related bloodstream infections by 49%²⁸ and has led to recommendations to replace povidone-iodine with chlorhexidine disinfectants. ²⁵ A comparison of isopropyl alcohol, povidone-iodine, and 2% chlorhexidine aqueous solution for disinfection of 668 central venous catheters in adults during insertion and routine dressing changes showed chlorhexidine to be significantly more effective in reducing catheter-related infections. ⁸¹ Similar studies have not been conducted in the NICU population. In a sequential study in a single NICU, the rate of positive blood cultures and number of true infections were unchanged when the unit switched from povidone-iodine to chlorhexidine gluconate for skin disinfection.⁷¹ Of note, the typical dwell time for central catheters in many of the studies is 7 to 10 days, whereas peripherally inserted central catheters in neonates are often in 3 weeks or longer.

Chlorhexidine gluconate (CHG) is currently available in the United States as a 2% aqueous CHG skin preparation in 4-ounce bottles, as a tincture of 2% CHG in 70% isopropyl alcohol (ChloraPrep) in single-use packaging, and as a wipe containing 0.5% CHG in 70% isopropyl alcohol. The tincture has been approved for infants older than 2 months, although many neonatal units use the tincture “off label” because of the convenience and decreased risk for contamination of bottled products. However, the combination of two disinfectants (CHG and isopropyl alcohol) has a significant potential for skin injury in very-low-birth-weight (VLBW) infants and cannot be recommended for them. All CHG products should not come in contact with the eyes or ears, per manufacturer’s recommendations, because of reports of damage to these structures. However, careful use before scalp intravenous or central line insertion is acceptable if splashing or using excessive amounts of CHG is avoided. CHG is applied in two consecutive wipings or for a 30-second scrubbing period and then is removed with sterile water or saline solution when the procedure is completed.

Many nurseries have chosen to continue the use of povidone-iodine disinfectants because of the lack of single-use CHG products that do not contain isopropyl alcohol. Povidone-iodine is available in a 10% aqueous solution in a variety of single-use applications. It is also applied in two consecutive wipings or for a 30-second scrubbing period and then is allowed to dry for at least 30 seconds before the procedure. Any solution should be completely removed after the procedure, using sterile water or saline solution to prevent any further absorption. Disinfection with isopropyl alcohol is questionable in the NICU, because it is less effective than either povidone-iodine or chlorhexidine and can be irritating and drying to skin surfaces.

The risks and benefits of routine skin antisepsis in infants is a subject that clearly deserves further investigation. Although there are insufficient comparative data on the costs, risks, and benefits of skin antisepsis regimens to mandate standard practice, the use of alcohol pledgets alone provides the least-effective antimicrobial activity. Povidone-iodine and isopropyl alcohol carry significant risks of percutaneous toxicity. The potential for subclinical toxicities must be considered with all products used on small newborns; therefore when several topical therapeutic options are available, the one with the least potential for toxicity should be chosen. In addition, disinfectants should be removed completely from the skin with water or saline to prevent further absorption and contact.

The routine use of antimicrobial sprays, creams, or powders for umbilical cord care has not been shown to be more effective in preventing infection compared with dry cord care.¹²⁸ The use of antibiotic ointments and antiseptics can prolong the time to cord separation, and it seems to have no beneficial effect on the frequency of infection. ^6,62,128 A study of 1811 newborns randomized to receive either routine isopropyl alcohol with each diaper change or natural drying found no umbilical infections in either group, and time to cord separation was reduced from 9.8 days in the alcohol-treated group to 8.16 days in the natural-drying group. ³⁸ Another study randomized 766 newborns to receive either triple dye applied to the umbilical cord immediately after delivery, followed by twice-daily applications of isopropyl alcohol, or “dry care” without any treatment. Infants in the dry-care group were more likely to be colonized with bacteria than those in the treatment group, and one infant in the dry-care group developed omphalitis on the third day of life. The days to cord separation were not reported. ⁶¹

The development of omphalitis is not necessarily related to cord disinfection, because it occurs also in infants who have received topical disinfectants. However, vigilant attention to the signs and symptoms is necessary by health professionals, and parents need guidance about how to manage the umbilical cord and when to consult their health care provider.³⁷

One of the most common practices in the NICU is the application and removal of adhesives that secure endotracheal tubes, IV devices, and monitoring probes and electrodes. A research utilization project involving 2820 premature and term newborns found that adhesives were the primary cause of skin breakdown among NICU patients.⁷⁸ Changes in TEWL and skin barrier function are seen in adults after ten consecutive removals of adhesive tape⁷² and after one removal of adhesive tape in premature infants. ⁵² Types of damage from adhesive removal include epidermal stripping, tearing, maceration, tension blisters, chemical irritation, sensitization, and folliculitis. ⁵⁴

Solvents are sometimes used to prevent discomfort and skin disruption from adhesive removal. They contain hydrocarbon derivatives or petroleum distillates that have potential or proven toxicities. Toxicity is a major concern, especially in premature infants with their underdeveloped stratum corneum, increased skin permeability, larger surface-area to body-weight ratio, and immature hepatic and renal function.