EXTERNAL COOLING METHODS— MULLER and DAMMANN 



417 



infant is different from that of the ackilt. According to Langer/° the comparative 

 concentration of fatty acids in infants and adults is as follows: 



Newborn Oleic 67.75% 



Adult Oleic 89.80% 



Palmitic 28.97% 

 Palmitic 8.16% 



Stearic 3.28% 

 Stearic 2.04% 



Oleic acid has a much lower melting point than the other constituents and the small 

 change in the relative proportions of these fatty acids results in a considerable 

 change in the melting point of the neutral fat. It was postulated, therefore, that 

 because of this, even slight changes in the temperature of the infant's fat can cause 

 solidification and subsequent necrosis. 



Blankets with coils containing a fluid. In this technique the temperature of the 

 fluid circulating through coils can l)e readily regulated (fig. 2). One can thus cool 

 or rewarm during an operation. The ecjuipment is expensive and somewhat cumber- 

 some ; the rate of cooling is relatively slow. During rewarming skin burns may 

 occur if the warming fluid is too hot. 



Air cooling by cold air chamber. A cold air chamber has been used by Cook- 

 son, Bailey, and associates. ^^ It has not received widespread acceptance in this 

 country. The method is cumbersome ; the rate of cooling is slow. Frostbite or pres- 

 sure gangrene is likely to occur in the digits and unprotected parts of the body. If 

 these are wrapped the rate of cooling is even more slow. Adams-Ray^^ has recently 

 reported a method of air cooling which is more rapid and which apparently avoids 

 these hazards (see Adams-Ray, Discussion, pp. 430 ff.). 



Fig. 2. — Production of hypothermia by circulating blanket. 



