Basal Heat Loss and Production in Women at Temperatures From 23°C to 36°C

Abstract

Recent work 1 2 3 on the effect of environmental temperature on heat loss in humans has been restricted to male subjects, most of them nude. The present report deals with similar studies on 3 normal women (nude). The methods were similar to those previously described. 1

The data are presented in Fig. 1, in which all variables are plotted as functions of the calorimeter temperature.

1. Rectal Temperature was about 0.15°C lower at 24°C than at 36°C.

2. Average Skin Temperature increased linearly with calorimeter temperature between 23°C and 33°C. These changes in skin temperature were due entirely to changes in the calorimeter temperature. At 33°C the skin temperature reached a high level and did not change with further increase in calorimeter temperature.

3. Heat loss decreased linearly with increasing calorimeter temperatures up to 31°C, and after reaching a low point of 29 cals/m²/hr at 32°C rose slowly with higher temperatures.

4. Heat production was constant between 23°C and 27°C at 35 cals/m²/hr. At 28°C, the heat production began to decrease slowly, closely following the heat loss. At 32°-33°C a low point in heat production, 29 cals/m²/hr was reached after which the heat production again increased following closely the heat loss. This change in heat production was observed in all 3 subjects and amounted to over 17% of the 35 calorie level.

5. Vaporization was practically constant between 23°C and 32°C. Sweating began between 32°C and 33°C. In this zone evaporation was that necessary to balance heat loss and heat production.

6. The conduction of the peripheral tissues was almost constant between 23°C and 28.5°C, and had a value corresponding to a thickness of tissue of 22 mm. The conduction increased linearly with temperature from 28.5°C to 36°C. Thus blood flow in the superficial tissues increased in proportion to the rise in environmental temperature.