Some effects of exposure to an environment of saturated air at mouth temperature

Heat balance during surgery involving body cavities

Three groups of adult patients were anaesthetized for elective intra-abdominal surgery. In one group, patients were ventilated with dry anaesthetic gases, and these patients all lost heat. In the second group humidification was used to annul respiratory heat exchange, and these patients lost heat initially but tended to regain heat during anaesthesia. The third group, in addition to humidification, had surface insulation and all these patients gained heat. It is suggested that conservative methods which negate heat loss are able to prevent hypothermia by the retention of metabolically produced heat.

The relation between sweat rate and weight loss when sweat is dripping off the body

1. The relation between the rate of sweat production, S, and the rate of weight loss, W, has been examined under conditions in which the rate of evaporation was small.2. S could be found from W provided that a film of liquid was maintained over the skin surface. This could be achieved initially by immersing the subject in water containing detergent. Thereafter the film was maintained so long as the rate of weight loss exceeded about 10 g/min.3. When the rate of weight loss was changing and the rate of evaporation was constant, S could be calculated as W + 2.5 W.4. When the subject was constantly sprayed with water while being weighed, the correction for W became negligible. In this case there was no lower limit to the sweat rate which could be measured, but spraying considerably reduced the accuracy of the measurement.5. The output of sweat from a ventilated capsule on the forearm correlated well with estimates of central sweating drive based on weight measurements corrected for hidromeiosis.

The effects of soaking the skin in water at various temperatures on the subsequent ability to sweat

1. The ability of two human subjects to produce sweat was measured before and after immersion for up to 4 hr in water at 32-36 degrees C (soak).2. The ability to produce sweat declined about 4 times as rapidly when the subject was soaked at 36 degrees C as at 32 degrees C.3. The rate of decline characteristic of soaking at 36 degrees C was shown by subjects exercising in water at 35 degrees C, but not at rest at 35 degrees C. The difference appeared to be related to the presence or absence of moderate sweating (300 g/hr) during the soak. At higher rates there was no further increase in the rate of decline.4. Soaking at 39 degrees C for 5 min, after which the water temperature was reduced to 33 degrees C, caused a decline consistent with the supposition that while the subject was sweating the rate of decline was the same as that at 36 degrees C and for the rest of the time the same as that at 32 degrees C.5. It is concluded that the rate of decline is increased if the sweat ducts are perfused, and some possible mechanisms are discussed.