Cutaneous circulation during dehydration and heat stress

Senay, L. C.; Christensen, Margaret L.

doi:10.1152/jappl.1965.20.2.278

Cited by 11 publications

(2 citation statements)

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“…It is interesting to note that in experiments on adults dehydration of about the same degree reduced the sweat rate [27], and the oral temperature was slightly higher by 0.1° [31].…”

Section: Sweatingmentioning

confidence: 95%

Thermal Balance of the Newborn Infant in a Heat-gaining Environment

1973

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ExtractThe 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 i nfants were subjected to the same experimental conditions: ambient temperature 37°, restive 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. Neonatal thermal balance 889In the new thermal equilibrium, the metabolic rate of the full term infants was about 20% lower than that measured under neutral ambient conditions. We suggest that the term "neutral thermal environment" must be reconsidered. SpeculationA new method, gradient layer direct calorimetry, gave us the opportunity to measure directly the different heat losses of the neonate under well controlled experimental conditions, and to compare thes...

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“…It is interesting to note that in experiments on adults dehydration of about the same degree reduced the sweat rate [27], and the oral temperature was slightly higher by 0.1° [31].…”

Section: Sweatingmentioning

confidence: 95%

Thermal Balance of the Newborn Infant in a Heat-gaining Environment

1973

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“…The subjects had at least 2-hr to correct any J. S. J. HAIGHT AND W. R. KEATINGE dehydration. Relatively severe fluid loss has only been reported to raise body temperature by 0.10 C (Senay & Christensen, 1965). Nor is it likely that the increase in body temperature needed to cause sweating resulted from fatigue of the sweat glands due to sweating during the period of exercise; sweat rate has been reported to decline during exercise in severe heat (Gerking & Robinson, 1946) but there was no evidence that this was accompanied by an increase in the threshold body temperature for sweating.…”

Section: Discussionmentioning

confidence: 99%

Elevation in set point for body temperature regulation after prolonged exercise

Haight¹,

Keatinge²

1973

The Journal of Physiology

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SUMMARY1. In nine healthy men, after prolonged exercise (approximately 37 km walk and 2-5 km ascent and descent in 9 hr) deep body temperature at rest stabilized at a higher level than in the absence of previous exercise.2. The increase, approximately 0.36°C, was recorded at both oral and rectal sites. It persisted while the subjects rested in warm and in cool surroundings, and disappeared about 11 hr after the end of exercise.3. The increase in body temperature after exercise was accompanied by a similar increase in the body temperature at which sweating started during body heating.4. After exercise the subjects' metabolic response to cold air (13.60 C) was normal or increased in spite of the elevation in body temperature.5. Blood glucose concentration was never lower than 3-1 mm during these experiments.6. The temperature changes are most easily explained by mild pyrexia due to the release of endogenous pyrogen associated with minor tissue damage.

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Effect of voluntary dehydration on thermoregulatory responses to heat in men and women

Grucza

Lecroart

Carette

et al. 1987

Europ. J. Appl. Physiol.

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The effects of dehydration prior to heat exposure on sweating and body temperature were tested in 8 men and 8 women, dehydration being 1.3 and 1.0% of body weight, respectively. The subjects were exposed to 40 degrees C for 60 min. Compared with controls (C), in the dehydrated men (D) there was a longer delay in the onset of sweating (C, 7.8, D, 11.6 min, p less than 0.05), a lower total sweat loss (C, 153, D, 127 g X m-2 X h-1, p less than 0.001), and a greater increase in Tre (C, 0.31, D, 0.43 degree C, p less than 0.002). In women, dehydration did not influence the control time course of sweating significantly, nor were these significant body temperature increases during heat exposure. Delay in the onset of sweating in women (C, 18.1, D, 18.7 min) was generally longer than in men (C, 7.8, D, 11.6 min), [F(1,14) = 7.41, p less than 0.05]. A significant correlation was found between the inertia time of sweating and delta Tre in both control and dehydration conditions in the men (r = 0.81, p less than 0.01). The rectal temperature increases in men were also related to the inertia time of electrical skin resistance (r = 0.83, p less than 0.01). It is concluded that dehydration affects sweating and body temperature in men more severely than in women.

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Cutaneous circulation during dehydration and heat stress

Cited by 11 publications

References 0 publications

Thermal Balance of the Newborn Infant in a Heat-gaining Environment

Thermal Balance of the Newborn Infant in a Heat-gaining Environment

Elevation in set point for body temperature regulation after prolonged exercise

Effect of voluntary dehydration on thermoregulatory responses to heat in men and women

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