Thermal balance of the newborn infant in a heat-gaining environment

E. Sulyok, E. Jéquier, L. S. Prod’Hom

Research output: Contribution to journalArticle

24 Citations (Scopus)

Abstract

The thermal balance of 22 full term, 9 small for date, and 8 large premature infants was studied by gradient layer direct calorimetry on the 1st day of life. In addition, the influence of muscular activity on the ability to sweat of 8 full term infants was investigated. The same measurements were repeated in 20 infants on the 3rd day of life. All infants were subjected to the same experimental conditions: ambient temperature 37°, re1ative humidity 50%, and air flow 30 liters/min. It was demonstrated that the evaporation of water was the primary way to dissipate heat in a heat-gaining environment. Active thermoregulatory sweating was elicited at deep body temperatures of 37.45°, 37.8°, and 37.76° in the full term, small for date, and premature infants, respectively. The set-point temperature of sweating tended to be lower with increasing gestational and postnatal age, and with vigorous muscular activity. The physiologic weight loss of about 3%, and the intrauterine growth retardation resulted in significant increase in this threshold temperature. The maximal sweat rate of the premature infants (1.43 W/kg) was significantly lower than that of the full term (1.81 W/kg) and small for date infants (2.32 W/kg): P <0.05 and 0.01, respectively. Heat loss by radiation and convection was directly related to the mean skin temperature; it was only when the latter reached the value of 37° that radiative plus convective heat loss became positive. There was a close inverse relation between the total heat loss and heat storage. After the beginning of sweating, the heat storage of full term and small for date infants sharply decreased and stabilized around 0, which showed that a new thermal steady state was reached. The premature infant was not able to reach this new equilibrium and the heat storage remained positive. The full term and small for date infants could keep the body temperature at a steady level of 37.66° and 37.98°, respectively, whereas the esophageal temperature of the premature infants kept on increasing. The cutaneous thermal conductance, an indicator of the heat-transferring blood flow, was at first negative, which showed that heat was transferred from the surface to the core. Later, before the evaporative heat loss, it increased and reached the maximal value at a body temperature of 37.6° in the normal, and of 37.9° in both the small for date and premature groups. The metabolic rate for the small for date and premature infants was significantly higher than that for the full term infants, and it directly related to the deep body temperature in each group.

Original languageEnglish
Pages (from-to)888-900
Number of pages13
JournalPediatric Research
Volume7
Issue number11
Publication statusPublished - 1973

Fingerprint

Hot Temperature
Newborn Infant
Premature Infants
Body Temperature
Sweating
Temperature
Sweat
Convection
Calorimetry
Fetal Growth Retardation
Skin Temperature
Humidity
Gestational Age
Weight Loss
Air
Radiation
Skin
Water

ASJC Scopus subject areas

  • Pediatrics, Perinatology, and Child Health

Cite this

Sulyok, E., Jéquier, E., & Prod’Hom, L. S. (1973). Thermal balance of the newborn infant in a heat-gaining environment. Pediatric Research, 7(11), 888-900.

Thermal balance of the newborn infant in a heat-gaining environment. / Sulyok, E.; Jéquier, E.; Prod’Hom, L. S.

In: Pediatric Research, Vol. 7, No. 11, 1973, p. 888-900.

Research output: Contribution to journalArticle

Sulyok, E, Jéquier, E & Prod’Hom, LS 1973, 'Thermal balance of the newborn infant in a heat-gaining environment', Pediatric Research, vol. 7, no. 11, pp. 888-900.
Sulyok, E. ; Jéquier, E. ; Prod’Hom, L. S. / Thermal balance of the newborn infant in a heat-gaining environment. In: Pediatric Research. 1973 ; Vol. 7, No. 11. pp. 888-900.
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abstract = "The thermal balance of 22 full term, 9 small for date, and 8 large premature infants was studied by gradient layer direct calorimetry on the 1st day of life. In addition, the influence of muscular activity on the ability to sweat of 8 full term infants was investigated. The same measurements were repeated in 20 infants on the 3rd day of life. All infants were subjected to the same experimental conditions: ambient temperature 37°, re1ative humidity 50{\%}, and air flow 30 liters/min. It was demonstrated that the evaporation of water was the primary way to dissipate heat in a heat-gaining environment. Active thermoregulatory sweating was elicited at deep body temperatures of 37.45°, 37.8°, and 37.76° in the full term, small for date, and premature infants, respectively. The set-point temperature of sweating tended to be lower with increasing gestational and postnatal age, and with vigorous muscular activity. The physiologic weight loss of about 3{\%}, and the intrauterine growth retardation resulted in significant increase in this threshold temperature. The maximal sweat rate of the premature infants (1.43 W/kg) was significantly lower than that of the full term (1.81 W/kg) and small for date infants (2.32 W/kg): P <0.05 and 0.01, respectively. Heat loss by radiation and convection was directly related to the mean skin temperature; it was only when the latter reached the value of 37° that radiative plus convective heat loss became positive. There was a close inverse relation between the total heat loss and heat storage. After the beginning of sweating, the heat storage of full term and small for date infants sharply decreased and stabilized around 0, which showed that a new thermal steady state was reached. The premature infant was not able to reach this new equilibrium and the heat storage remained positive. The full term and small for date infants could keep the body temperature at a steady level of 37.66° and 37.98°, respectively, whereas the esophageal temperature of the premature infants kept on increasing. The cutaneous thermal conductance, an indicator of the heat-transferring blood flow, was at first negative, which showed that heat was transferred from the surface to the core. Later, before the evaporative heat loss, it increased and reached the maximal value at a body temperature of 37.6° in the normal, and of 37.9° in both the small for date and premature groups. The metabolic rate for the small for date and premature infants was significantly higher than that for the full term infants, and it directly related to the deep body temperature in each group.",
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