Heat loss from the skin of preterm and fullterm newborn infants during the first weeks after birth

Newborn infants lose heat rapidly at birth and during the first half hour of life. This investigation was undertaken to determine whether the initial heat loss was due principally to evaporation, and whether or not establishment of breathing would be irregular or delayed if the initial cold stress was reduced. Five groups, each of 10 infants, were studied during the first half hour of life. Infants in Groups I and IV remained wet and were exposed to either room air or placed under a radiant heater. Those in Groups II, III, and V were dried promptly and exposed to room air, wrapped in a blanket or warmed by means of a radiant heater. Heat loss due to radiation and convection together was twice that from evaporation. Reduction of cold stress by placing the infant under a radiant heater as soon as he is born does not impede or delay the onset of breathing. Wet infants exposed to room air lost nearly five times more heat than those who were dried and warmed. In vigorous infants, the simple maneuver of drying and wrapping in a warm blanket is almost as effective in diminishing heat loss as placing them under a radiant heater. However, in depressed or immature infants who may be more asphyxiated or have reduced energy stores, radiant heat maintains body temperature while allowing access to the patient.

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Heat Loss from the Skin of Preterm and Fullterm Newborn Infants during the First Weeks after Birth

Neonatology ◽

10.1159/000242554 ◽

1986 ◽

Vol 50 (1) ◽

pp. 1-10 ◽

Cited By ~ 49

Author(s):

Karen Hammarlund ◽

Bo Strömberg ◽

Gunnar Sedin

Keyword(s):

Heat Loss ◽

Newborn Infants

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RESPIRATORY CONTRIBUTION TO THE THERMAL BALANCE OF THE NEWBORN INFANT UNDER VARIOUS AMBIENT CONDITIONS

PEDIATRICS ◽

10.1542/peds.51.4.641 ◽

1973 ◽

Vol 51 (4) ◽

pp. 641-650

Author(s):

E. Sulyok ◽

E. Jéquier ◽

L. S. Prod'hom

Keyword(s):

Ambient Temperature ◽

Heat Loss ◽

Newborn Infant ◽

Thermal Environment ◽

Newborn Infants ◽

Thermal Balance ◽

Evaporative Heat Loss ◽

Ambient Conditions ◽

Direct Calorimetry ◽

Respiratory Heat Loss

The influence of environmental humidity and temperature on the thermal balance of 45 full-term newborn infants was studied by direct calorimetry within 24 hours after birth. The respiratory heat loss measured at 32C and 20% relative humidity (RH) represented 9.5% of the total heat production, and it decreased to 2.9% when RH was 80%. In neutral thermal environment (32C, 50% RH), the mean respiratory heat loss was lower than that measured during a warm exposure (36C, 50% RH), in spite of a higher absolute humidity in the latter condition. This suggests that respiration might have a thermoregulatory function during heat exposure in the newborn. Evaporative heat loss from the skin was more elevated than that from the respiratory tract, but it was less sensitive to change in ambient humidity. Convective and radiative heat losses from the skin were inversely related to ambient temperature; similarly, the metabolic rate decreased with increasing ambient temperature up to 36C. This work provides further data on the varying energy exchange between the newborn infant and his environment; it should lead to a more rational planning of infant care and caloric requirements and demonstrates the important effects of different environmental conditions on the newborn infant.

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Partitioning of Heat Losses and Gains in Premature Newborn Infants Under Radiant Warmers

PEDIATRICS ◽

10.1542/peds.75.1.89 ◽

1985 ◽

Vol 75 (1) ◽

pp. 89-99 ◽

Cited By ~ 1

Author(s):

Stephen Baumgart

Keyword(s):

Metabolic Rate ◽

Heat Loss ◽

Newborn Infants ◽

Radiant Heat ◽

Heat Losses ◽

Evaporative Heat Loss ◽

Convective Heat Loss ◽

Radiant Warmer ◽

Different Levels

The partition of heat loss into convective and evaporative components, and heat gain into metabolic rate of production and radiant heat needed to maintain thermal equilibrium was determined in ten premature neonates (weight 1.39 ± .08 [SEM] kg, gestation 31 ± 1 weeks) who were nursed naked and supine on open radiant warmer beds. Warmer beds were servocontrolled to maintain each infant's abdominal skin temperature at three different levels: 35.5, 36.5, and 37.5°C. The quantity of radiant heat delivered by the warmer in vivo was measured directly and compared with the heat need calculated from the partition. Convective heat loss comprised the major component of net heat loss and increased significantly with servocontrol temperature from 2.86 ± .24 to 3.27 ± .23 kcal/kg/h (P < .01), and to 3.72 ± .26 kcal/kg/h (P < .001). Evaporative heat loss increased with servocontrol temperature from .96 ± .13 to 1.41 ± .33 kcal/kg/h, and to 1.35 ± .32 kcal/kg/h, but this increase was not significant. Metabolic rate decreased from 2.08 ± .17 to 1.90 ± .14 kcal/kg/h, and to 1.78 ± .16 kcal/kg/h with increased servocontrol temperature, but this decrease was not significant. Radiant heat needed to maintain infants at higher temperatures increased from 1.73 to 2.80 kcal/kg/h, and to 3.32 kcal/kg/h. The radiant heat delivered by the warmer to infants was directly proportional to the heat need calculated from the partition (r = .68, P < .001).

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NEW STANDARDS FOR “BASAL” HEAT PRODUCTION AND EVAPOR ATIVE AND NON-EVAPORATIVE HEAT LOSS IN LOW BIRTH WEIGHT NEWBORN INFANTS?

Pediatric Research ◽

10.1203/00006450-197704000-01013 ◽

1977 ◽

Vol 11 (4) ◽

pp. 539-539 ◽

Cited By ~ 1

Author(s):

A Okken ◽

J H P Jonxis ◽

P Rispens ◽

W G Zylstra ◽

M Klaus

Keyword(s):

Birth Weight ◽

Low Birth Weight ◽

Heat Loss ◽

Heat Production ◽

Newborn Infants ◽

Evaporative Heat Loss

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DIAGNOSIS AND TREATMENT: USE AND MISUSE OF TEMPERATURE AND HUMIDITY IN CARE OF THE NEWBORN INFANT

PEDIATRICS ◽

10.1542/peds.33.2.276 ◽

1964 ◽

Vol 33 (2) ◽

pp. 276-277

Author(s):

William A. Silverman

Keyword(s):

Heat Loss ◽

Newborn Infant ◽

Newborn Infants ◽

Convincing Evidence ◽

Ambient Conditions ◽

Cool Environment ◽

Temperature And Humidity ◽

Production Body ◽

The Moment ◽

Treatment Use

INFANTS delivered from the warm uterus into a cool environment invariably experience a considerable loss of body heat, and since the rate of cooling is almost always greater than the rate of heat production body temperature promptly falls. The rate of fall, the final level of equilibrium, and the distribution of temperatures of the various tissues and organs are quite dependent upon the ambient conditions of temperature and humidity which are provided for infants in the first minutes, hours, and days of life. If the artificial climate is too warm and humid to allow for the dissipation of heat liberated by metabolic processes the newborn infant becomes febrile and tachypneic. This is particularly likely in small infants whose physiologic mechanisms of heat loss are easily overwhelmed. The environmental conditions must be adjusted because death from hyperthermia may ensue rather quickly. However, there is usually no problem of recognition when warm limits have been exceeded; as a result temperature and humidity are never deliberately misused in this way in the care of newborn infants. Induced hyperthermia is almost always the result of technical accidents. Since there is now convincing evidence that newborn infants exhibit homeothermic responses to thermal stimuli and that the survival of small neonates can he improved by placing them in warm and moderately humid environments, it may also be said that physicians rarely misuse temperature and humidity in a manner which would permit uncontrolled heat loss. Thus, if we omit the issue of deep hypothermia for the moment the present-day questions about the proper use of temperature and humidity are concerned not with the extremes but with the middle of the climatic scale.

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