The Water Metabolism of Newborn Infants

Clinical experience leaves no doubt that the water metabolism of infants differs from that of normal adults. This difference emerges not only from the well known facts that an apparently small decrease of fluid intake or increase of the fluid loss may produce clinical symptoms of dehydration, but it is also evident from the ease with which oedema may be produced by ' therapeuticl 'administration of fluids to newborn children. In practice dehydration in infants mainly seems to occur in two conditions. First, where a normal intake of food is not balanced by a sufficient intake of water (Rietschel, 1934; Finkelstein, 1938). Secondly, when diarrhoea and vomiting lead to excessive losses of fluid and certain elctrolytes. Dehydration undoubtedly remains the chief cause of the continued high fatality rate in cases of infantile diarrhoea and vomiting. Its prevention or early correction constitutes the most important factor influencing recovery. However, the therapeutic problem in cases of dehydration is clearly not a simple one: the amount and composition of the fluid to be given and the route of admiistration require careful consideration and if, as may be necessary, intravenous application has to be chosen, the rate of infusion will also need to be watched carefully. Decisions as to therapeutic measures covering these factors have frequently still to be made on empirical grounds. It is therefore not surprismg that instances of gross oedema are observed (Arnott and Young, 1942; Alexander, 1948). Death in infants after intravenous adminis tration of fluids has also been ascnrbed to cardiac failure due to overloading of the cirulation (Alexander, 1948). Water depletion and salt depletion will have to be kept apart as in adults but it is clear that more knowledge of the water metabolism of infants is required. T"ne analysis of the effects of dehydration and rehydration in adults forms the necessary basis for such studies, but it would clearly be a serious