On the measurement of evaporative water loss : methods and clinical applications

Abstract: The new method for measurement of water loss by evaporation from the skin described in paper I, offers a high degree of accuracy and improved sensitivity in comparison with devices reported previously. Rapid recordings can be made by technically untrained persons both in clinical departments and in the laboratory.Using this method, the average insensible perspiration from the skin of healthy adult subjects at rest was found to be 381, 526 and 695 gr per day at ambient temperatures of 22°, 27° and 30°C, respectively. On the head, hands and feet the evaporation rate was high, while on other body surface areas more moderate values were recorded,In a clinical study on newborn infants, a linear relationship between the evaporative water loss from the skin and the ambient humidity was found. At an ambient temperature of 34.5°c and an ambient relative humidity of 50% the average transepidermal water loss was calculated to be 8.1 g/m2h.In burned patients high evaporation rates from about 140 g/m2h to over 220 g/m2h were recorded on the injured skin surfaces. Biological dressings were only slightly permeable to water vapour, while the permeability of the artificial dressings tested was generally high.By recording the rate of increase in vapour concentration in a closed measurement chamber placed over the exposed abdominal cavity during surgery, the water loss by evaporation from wounds and exteriorized viscera was determined. At incisions of minor extent the evaporative water loss was low, while at larger incisions with exteriorized viscera the water loss by evaporation from the wound exceeded the basal cutaneous perspiration of healthy adult subjects.