Surface electrical capacitance as a noninvasive bedside measure of epidermal barrier maturation in the newborn infant

The classical studies of epidermal barrier function in infants have relied on measurement of transepidermal water loss by evaporimetry. This technique, although valuable, is, in practice, slow, expensive, and susceptible to error because of convective air currents. In this prospective study, we evaluated gestation-dependent and postnatal age-dependent changes in epidermal barrier function by measurement of skin surface electrical capacitance (SEC) in 40 newborn infants ranging from 25 to 40 weeks' gestational age. SEC was measured in picofarads with a dermal phase meter.

The measurements were recorded continuously during a 12-second period from the forehead at 12 to 24 hours of life. The baseline (CBL) surface hydration at 1 second and the rate of change of SEC during probe occlusion (CSL) were used as measures of surface hydration and transepidermal water movement, respectively. In the most premature infants (< 30 weeks), these measurements were repeated daily for 5 days. Data were analyzed by analysis of variance after logarithmic (Ln) transformation.

We found a significant difference in Ln(CBL) in infants born before and after 30 weeks' gestation (4.91 +/- 0.36 Ln[pF] vs 2.67 +/- 0.21 Ln[pF], respectively). Similarly, CSL was significantly different in infants born before and after 30 weeks' gestation (16.42 +/- 5.55 pF/s vs 1.59 + 0.22 pF/s, respectively). In infants born at less than 27 weeks, both Ln(CBL) and CSL decreased significantly by postnatal day 5. In the term group (n = 25), CSL was significantly greater in white than in black infants (1.96 +/- 1.32 pF/s vs. 0.95 +/- 0.55 pF/s, respectively).

These results demonstrate impaired epidermal barrier properties in immature infants, less than 30 weeks' gestation, and reveal a remarkable rate of barrier maturation of this group in the first few days of postnatal life. Also, the finding of decreased CSL in black infants supports the hypothesis of differences in barrier function attributable to skin types. Overall, these findings demonstrate the feasibility of bedside SEC measurements in the evaluation of epidermal barrier properties in the newborn infant.