EDEMA 155 



Fischer(a)(1910), on the basis of experiments with the swelling of 

 frog's muscle, supported the view that the cause of edema lies in the 

 tissues, and concluded that it is due to swelling of the colloids of the 

 tissues, as a result of increased acid production. 



Achard and Loeper (1901) called attention to the importance of 

 sodium chlorid in the maintenance of the balance of fluid between the 

 blood and tissues, and concluded that the tissues were injured by sub- 

 stances retained by the kidneys, the result being a withdrawal of salt 

 from the blood by the injured tissues. 



Widal (1903), in his classical experiments with Lemierre and with 

 Javal, showed that edema could be produced and made to disappear at 

 will, in certain cases at least, by varying the salt intake of patients. 



Strauss (c)(d)( 1903) also called attention to the importance of the 

 retention of sodium chlorid, explaining edema on the basis of insufficient 

 excretion of salt, resulting in the retention of water, due to increased 

 osmotic pressure. 



Epstein (6) (1917) has concluded, as did the followers of Bright, that 

 the primary cause of edema is the diminution of the protein content of the 

 blood, due to the loss of protein through the kidneys. 



The Problem of Edema. Whatever may be the primary cause of 

 edema, whether it is renal insufficiency, with respect to the elimination 

 of water or of salt, or the loss of protein from the blood, or injury to the 

 capillaries, by mechanical or chemical causes, or a disturbance in the 

 metabolism of the tissue cells, the problem of edema is the problem of 

 the interchange of fluid, with its dissolved and suspended substances, be- 

 tween the blood and the tissues. As this interchange of fluid is concerned 

 with the nutrition of the cells, the carrying off of products of cell metab- 

 olism, and the regulation of volume of the cells, the problem is ultimately 

 that of cell metabolism. For a perfect understanding of the process of 

 fluid exchange between the blood and the tissues, it is necessary to have a 

 picture more clear than is available of the interrelations of the various 

 physical, chemical, and physico-chemical processes which are involved. It 

 is at present desirable to analyze, as fully as possible in the light of present 

 knowledge, the mechanism underlying this process, especially under the 

 abnormal conditions associated with edema. 



For this purpose this discussion is limited, as far as possible, to the 

 general aspects of edema, avoiding extensive description of special types. 

 The clinical, pathological, and experimental features of the condition are 

 considered first objectively. There follows an analysis of the mechanism 

 from the physico-chemical viewpoint, and a discussion of the special 

 treatment, insofar as it relates to the pathology of metabolism. The 

 purely local effusions, such as hydrocele, and the inflammatory exudations 

 are not discussed, except insofar as they throw light on the general 

 problem of edema. 



