Neonatal water and heat exchange : The influence of environmental factors and infant maturity

Abstract: The environment provided by commonly used infant incubators, the effect of radiantheat and exposure to cold air on the exchange of water and heat between newborninfants and their environment, and the water loss through the skin of infants born at24-25 weeks of gestation were investigated. The evaporation of water from the skinwas measured by the gradient method. Respiratory water loss and oxygenconsumption was measured with a method for indirect calorimetry, equipped foranalysis of water vapour.Incubators with double walls and with the flow of air from the incubators heatsource directed between those walls had more homogenous air and inner hoodsurface temperature distributions. Term newborn infants exposed to a reducedambient air temperature reacted with an increase in respiratory water loss andoxygen consumption and a decrease in peripheral skin blood flow and skintemperature before central body temperature was affected, indicating an increasednon-shivering thermogenesis. Term and preterm infants nursed under a radiantheater had a increased rate of evaporation of water from the skin, which is due to thedifference in ambient humidity, and not to an effect of the non-ionising radiation onthe permeability of the skin. Term and preterm infants nursed in an incubator with anadded radiant heat source reacted with increased skin temperature and reducedradiative heat loss. In preterm infants born at 24 and 25 weeks of gestation,transepidermal water loss was high during the first two days after birth and thendecreased at a slower rate than previously reported for a group of slightly lesspreterm infants.

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