Insensible water loss in infants

Abstract

HE PHENOMENON of insensible loss of water was first noted by Sanetorius in 1614, when he suspended himself from one arm of a beam balance and observed a progressive weight loss2 He conceived the name perspiratio insensiblis for the insensible, or evaporative, water loss that occurs through the skin and lungs. Interest in insensible water loss was first directed to the observation made by Benedict 2 that there was a constant relationship between evaporative loss o,f water and dissipation of energy as heat. Isensehmidt 3 described the quantitative relationship between insensible loss of water and insensible weight loss by taking into account the difference between the weights of carbon dioxide produced and of oxygen consumed. Elaborate devices 4 were constructed (Fig. 1A, B) in order to achieve accurate weighing of whole individuals. Attention was paid to the influences of enviromnental variation on accuracy of weighing and to their physiologic effects on rates of water loss. Establishment of basal conditions for the measurement of insensible weight loss was an important part of any evaluation of evaporative water loss as a function of expenditure of energy. The growing recognition of the importance of water and electrolyte metabolism stimulated a consideration of Sanctorius' perspiratio insensiblis from another point of view, Loss of water through skin and lungs was an important final pathway of water metabolism and was a significant factor in the negative portion of the many bar-charts that began to appear in scientific journals in the 1940's. Repetition of the earlier weighing experiments was obviated by the elaborate nature of the experimental design, and so the data obtained by the early workers in the field of insensible weight loss served as the basis for clinical formulae of water replacement. The exhaustive data obtained by Levine and co-workers, 5-7 among others, s-9 provided the basis for calculation of insensible water loss in infancy and childhood and riley have survived to the present as part of our modern day calculations for water needs in the pediatric age group. It should be remembered that these data were obtained under basal conditions, or at least as close to basal as the experimenters were able to obtain.