Original Article Effect of Radiant Warmer on Transepidermal Water Loss (TEWL) and Skin Hydration in Preterm Infants A. Maayan-Metzger G. Yosipovitch E. Hadad L. Sirota OBJECTIVE: To evaluate the effect of radiant warmers on skin barrier function in preterm infants. METHODOLOGY: Transepidermal water loss (TEWL) and stratum corneum hydration were measured in 30 preterm infants (birth weight 825 to 2220 g) in seven body areas: forehead, upper back, cubital fossa, palms, soles, abdomen, and inguinal region. Measurements were performed under radiant warmer and incubator conditions. Each patient served as his/her control. RESULTS: TEWL was significantly higher in the radiant warmer compared to the incubator condition in only two areas: forehead and back. The overall mean difference in percentage TEWL between the conditions was 15%. Stratum corneum hydration was not affected by the radiant warmer. CONCLUSIONS: The use of radiant warmers does not significantly decrease barrier function in the preterm infant. Journal of Perinatology (2004) 24, 372–375. doi:10.1038/sj.jp.7211107 Published online 8 April 2004 INTRODUCTION The stratum corneum (SC) plays a key role in maintaining life because it inhibits water loss from the tissues while preventing the entry of damaging microorganisms. In preterm infants, the SC layer is thinner and less well developed than in full-term infants and adults, leading to high water loss and cutaneous infections, with high morbidity and mortality. 1–3 Radiant warmers are widely used for sick preterm and term newborns to effectively control body temperature and provide uniform heating over exposed body areas. However, several researchers have suggested that radiant warmers may affect insensible water loss. 4,5 Radiant warmers can also induce rapid drying of the skin surface. 6 In recent years, noninvasive techniques that can accurately measure the transepidermal water loss (TEWL) and skin hydration have been developed, 7–9 which also take environmental factors such as humidity and ambient temperature 9 into account. The purpose of the present study was to evaluate the effect of radiant warmers on TEWL and SC hydration in preterm infants using noninvasive devices mentioned above. MATERIALS AND METHODS Patients The study group included 30 preterm infants born at Schneider Children’s Medical Center of Israel from January to June 1998. There were 13 male and 17 female infants, all appropriate for gestational age. The mean gestational age was 31.6 weeks (range 27 to 34 weeks), and mean birth weight was 1588 g (range: 825 to 2220 g). Infants with respiratory distress, low blood pressure or suspicion of sepsis, and infants who required ventilatory support were excluded from the study, although infants receiving antibiotic treatment were not. The study was approved by the Ethics Committee of the hospital, and informed consent was obtained from the patient’s parents. Instruments To measure TEWL and SC hydration, we used a combined Tevameter and Corneometer (Courage and Khazaka, Ko ¨ln, Germany). The Tevameter device, a cylindrical probe consisting of two hydrosensors, is designed to measure the rate of water evaporation from the skin surface. TEWL was calculated from the slope provided by the hydrosensors and was computed by averaging the data recorded every 2 seconds; starting 90 seconds from the time the probe was applied to the skin. The Corneometer measures the electrical capacitance at the skin surface, an indicator of SC hydration. Its operation is based on the high dielectric constant of water relative to other skin components. The results are expressed in arbitrary units. Address correspondence and reprint requests to A. Maayan-Metzger, MD, Department of Neonatology, Schneider Children’s Medical Center of Israel, 14 Kaplan Street, Petah Tiqva 49 202, Israel. Department of Neonatology (A.M-M., L.S.), Schneider Children’s Medical Center of Israel, Israel; Department of Dermatology (G.Y., E.H.), Rabin Medical Center, Beilinson Campus, Petah Tiqva, Israel; and Sackler Faculty of Medicine (G.Y., E.H.), Tel Aviv University, Tel Aviv, Israel. Journal of Perinatology 2004; 24:372–375 r 2004 Nature Publishing Group All rights reserved. 0743-8346/04 $30 www.nature.com/jp 372