Modélisation des échanges thermiques du nouveau-né par mannequin thermique : applications biomédicales

Abstract

The body heat losses of premature neonates are difficult to assess since they are modified by the anthropomorphic characteristics of the infant. To solve this problem, thermal mannequins have been designed. The goal of the present study was to describe the biomedical uses of these models from two studies. The first one deals with the relationship between the thermal stress, the sleeping body positions and the sudden infant death syndrome, and the other with the assessment of heating devices used in neonatal surgery. A multisegment anthropomorphic thermal mannequin which represents a low-birth-weight neonate (body mass of 1,400 g) has been designed. In the first study, the mannequin was laid in prone or supine sleeping positions in a closed incubator, the air temperatures of which ranging from 25°C to 37°C. The results pointed out that the heat losses did not depend on the body positions. This discards the hypothesis that the supine sleeping position induces a thermal stress which can increase the mortality. In the second study, the mannequin was laid in a supine position in experimental conditions simulating an operative field. The thermal efficiency of a warming mattress associated (or not) with a convective warming device (Bair Hugger ®) has been tested (air temperatures between 20°C and 30°C). The results showed that the Bair Hugger ® was the most efficient device to rewarm the infant. When the Bair Hugger ® (air temperature 38°C) is associated with the warming mattress (39°C), the air temperature of the surgery room can be reduced from 27°C to 20°C, to improve the thermal confort of the operators without strong disturbances of the thermal balance of the infant.