Effects of Metabolic Disturbances in Infants 157 



fluid compartment. Hence the size of the latter appears to 

 increase with the progress of malnutrition (Kerpel-Fronius 

 and Kovach, 1948; McCance, 1951; Keys et al, 1950). 

 Haemodynamically, however, it is not the amount relative 

 to body weight but the absolute amount of extracellular 

 fluid which is of importance. Fig. 2 illustrates a striking 

 example of a case studied in comparison with well nourished 

 infants of the same length, first in a state of malnutrition and 

 later after dehydration due to diarrhoea had supervened. 

 In the malnourished infant the volume of the extracellular 

 fluid showed a percentage increase before and even after 

 diarrhoea. However, the "absolute amounts", i.e. the fluid 

 volumes calculated as percentages of those in normally 

 nourished infants of the same length, were decreased. Since 

 the haematocrit readings were high, the circulation time 

 prolonged, and the renal clearances low, high water reserves 

 calculated as a percentage of the body weight w^ere clearly 

 insufficient to maintain circulation and kidney function. The 

 absolute volume of the water reserves, and not just the amounts 

 proportional to the body weight, must be maintained in order 

 to conserve a normal circulation and good renal function. 



Let us now consider the normal infant. When compared 

 with the adult, his extracellular water reserves — although high 

 in terms of percentage of body weight — are strikingly low in 

 relation to other physiological needs, namely oxygen con- 

 sumption, insensible perspiration and cardiac output (Fig. 3). 



Thus when compared on the basis of body surface, the infant 

 appears to have the same oxygen consumption and cardiac 

 output as the adult, but his systolic output (stroke volume) 

 and plasma volumes are only half those of the adult; in 

 order to achieve the requisite cardiac output with a relatively 

 low plasma volume, the pulse rate is double that of the adult. 

 His inulin and ^-aminohippuric acid (PAH) clearance values 

 are low in comparison with those of the adult and also in 

 relation to his own cardiac output and metabolism. All his 

 fluid compartments are strikingly low in proportion to meta- 

 bolism, insensible perspiration and cardiac output. 



