GENERAL CAUSES OF EDEMA 293 



dropsy, and supports the belief that here and in cardiac dropsy 

 osmotic pressure plays a more important part than it does in 

 inflammatory exudation. Of the crystalloids that cause accu- 

 mulation of fluid in the tissues, sodium chloride seems to be the 

 most important. 



Retention of Chlorides in Edema, 1 From the investigations made 

 by numerous clinicians, especially the French, there seems to be no 

 question but that (1) in nephritis with edema a retention of sodium 

 chloride frequently occurs ; (2) that elimination of the chlorides is often 

 increased during periods of improvement of the edema ; (3) that a 

 reduction of the amount of chlorides in the diet often causes a great 

 improvement in the edema, while administration of chlorides may make 

 the edema much worse. There are, however, observations that also 

 indicate that chloride retention does not account for all cases of renal 

 dropsy, for many instances have been observed in which the above-men- 

 tioned conditions were not fulfilled. Nevertheless, it cannot be denied 

 that chloride retention is often an important causative factor in the 

 edema of parenchymatous nephritis. If the retained chlorides obeyed 

 the ordinary laws of diffusion, we should expect them to become distrib- 

 uted alike in the blood and tissues, so that they would merely cause an 

 equal increase in the fluids of the blood and of the tissues; that is to 

 say, there would be an hydremic plethora due to retention of water in 

 the body by the accumulating chlorides. But, according to a number of 

 observers, there is a specific retention in the tissues, which Strauss calls 

 " historetention," and which explains the local edema. The way in 

 which the historetention is produced is, however, not understood, and 

 not all observers accept this hypothesis (Scheel 2 ). In many conditions 

 other than nephritis, there is also a chloride retention (e. g., pneumonia, 

 cardiac incompetence, sepsis, typhoid), and the edemas observed in 

 these diseases may possibly depend upon chloride retention, as many 

 French authors suggest. Rumpf, indeed, often found more chlorides in 

 edematous fluids of non-nephritic origin than in nephritic edema. 



Inflammatory Edema. Although here the alterations in 

 the capillary walls play an essential role, as' shown by the pro- 

 teid-rich nature of the exudates, yet most of the other factors 

 are added. Increased blood pressure is prominent ; lymph out- 

 flow is impeded by plugging of the lymphatic channels by 

 clots and leucocytes, and by pressure on the outside ; there is, 

 undoubtedly, an excessive formation of metabolic products in 

 the tissues, to cause exosmosis. To this class of edemas belong 



1 Literature, resum6 by Widal and Javal, Jour. Physiol. et Pathol., 1903 

 (5), 1107 and 1123; also articles by Castaigne and Rathery, Semaine Med., 

 1903 (23), 309 ; Widal and Javal, Presse Med., 1903 (11), 701; Ambard and 

 Beaujard, Semaine Med., 1905 (25), 133; Koziczkowsky, Zeit. klin. Med., 1904 

 (51), 287 ; Bing, Berl. klin. Woch., 1905 (42), 1278 ; Strauss, Zeit. klin. Med., 

 1902 (47), 337; Ferrannini, Cent. f. inn. Med., 1905 (26), 1; Miller, Jour. 

 Amer. Med. Asso., 1905 (45), 1915; Rumpf, Munch, med. Woch., 1905 (52), 

 393. Review in Albu and Neuberg's " Mineralstoffwechsel," Berlin, 1906, pp. 

 171-178. 



2 Hospitalstidende, 1904, p. 1017. 



