International audienceThe present study aimed at assessing the net gain of body heat storage induced by a transparent plastic blanket draped over small premature neonates in the prone and the supine positions. Thermal stress is particularly important in premature and small-for-gestational-age infants characterized by high values of the ratio between skin surface area and body mass, the greater this ratio, the greater the body heat exchanges. The large skin permeability enhances body water loss. The risk of hypothermia is particularly increased at birth and during operations on naked neonates implying opening of the canopy (surgical operation, blood sampling and gastric aspiration). In the first day of life, the rate of evaporation can reach 100 g.h-1.m-2 in very preterm infants. To prevent the large amount of water loss it is sometimes recommended to cover the neonate with a plastic blanket. In closed incubator Fanaroff et al.(3) pointed out that a transparent plastic heat shield reduces the insensible water loss of 44 % in low birth weight neonates lower than 1250 g and postnatal age less than 10 days. For postnatal age greater than 10 days, the magnitude of this reduction was only 19 %. Bell et al.(2) also reported that the addition of a heat shield in an incubator decreased the water loss by 10 % in infants with mean birth weight of 1570 g. However the efficiency of this solution which depends on the physical environment but also on the inter individual difference in the ability to exchange heat with the environment remains questionable and the use of a plastic blanket is still a controversial topic. The total heat loss of premature infants depends on various factors such as gestational age, nutritional state, mean skin temperature, body hydromineral balance, vigilance state, metabolic rate and of the postnatal age which modifies the skin keratinisation. Thus, it is difficult to obtain homogeneous data base that takes into account all these factors and there are conflicting data on the effectiveness of plastic blanket. To rule out these confounding factors we use a sweating mannequin the advantage of which is that it measures directly the total heat loss with the environment without interference with these factors
