Transepidermal Water Loss in Extremely Preterm Infants

Background: Earlier studies have shown that transepidermal water loss is a major cause of fluid and heat loss in preterm infants. The aim of this study was to determine the rate of evaporation from the skin in relation to postnatal age in extremely preterm infants.

Subjects: Ten infants born at 25 weeks gestation, mean birth weight 707 g (range 481-805), were studied on the first day after birth. Antenatal corticosteroid treatment was given to the mothers of 8 infants. Six of the infants were also studied at a postnatal age of 2 and 6 days.

Interventions: Body and skin temperature (T_B, T_s;°C) and evaporation rate (ER; g/m²h) were measured in a controlled ambient temperature (T_AMB; °C) and relative humidity. (RH;%). As T_AMB and RH varied between measurements, ER was also corrected to RH 50% (ER₅₀). Transepidermal water loss (TEWL, TEWL₅₀; g/m²h) was calculated from ER and ER₅₀.

Results: On the first day after birth mean TEWL₅₀(n=10) was 59.3±11.6 (SD), i.e. >20% lower than in earlier studies. The table shows the values for the 6 infants studied at a postnatal age of ≤1, 2 and 6 days (^* =p<0.05,^**=p<0.01, compared to the first day after birth).

Table 1

Conclusion: TEWL is high on the first day after birth and decreases gradually. TEWL was lower than previously reported, which might be due to the use of antenatal corticosteroids.