344 , EDEMA 



"by Heidenhain. It is impossible at this time to eliminate as non- 

 existent this secretory-activity doctrine, but, as we hope to show later, 

 there exist other factors in all these non-inflammatory edemas that 

 are suff'.cient to account for the edema without our having recourse to 

 this hypothesis. For the present, therefore, we may consider altered 

 capillary permeability as an essential factor in edemas characterized 

 by protein-rich fluids (exudates), and state that the influence of al- 

 tered permeability in the production of protein-poor fluids (trans- 

 udates) is not proved, and is perhaps not of importance, although 

 the evidence of recent studies on experimental nephritis seems to 

 point more and more to the importance of vascular changes in acute 

 nephritis, at least. ^° 



5. Increased Filterability of the Blood Plasma. — This takes 

 us back to Richard Bright's conception of renal drops}'. He im- 

 agined that through the great loss of albumin in the urine the blood 

 became so thinned and w^atery that it could filter through the vessel- 

 walls, while normal plasma, he thought, was too thick and viscid to do 

 so. The same idea was applied to the edemas of cachexia in cancer, 

 etc., chlorosis, and all forms of edema associated with a decrease in 

 the corpuscular or protein elements of the blood. With our present 

 knowledge of diffusion of crystalloids and colloids we can readily ap- 

 preciate that a decrease in the blood colloids, such as might occur in 

 these diseases, could not facilitate the filtration of fluids through the 

 capillary walls to any considerable degree. On the other hand, the 

 amount of colloids in the blood will greatl}' modify' the amount of 

 fluid held in the blood; e. g., acacia is used in intravenous injections 

 because it holds in the blood vessels a large amount of fluid by virtue 

 of its hydrophilic character. 



Stewart and Bartels considered that in renal dropsy the increased 

 filterability of the plasma was not due so nuich to the loss in albumin 

 as to retention of water, which caused an hydremic plethora. But 

 this factor was soon eliminated, for it was found that complete anuria, 

 produced by ligating both ureters, does not cause edema; and also 

 that to produce an edema by increasing the water of the blood it was 

 necessary to increase it many times an nmch as it can ever be increased 

 by disease. Simply increasing the proportion of water by removing 

 part of the blood and injecting a corresponding amount of salt solu- 

 tion did not cause edema (Cohnheim and Lichtheim). We may, there- 

 fore, look upon the hypothesis of increased filterability of the blood as 

 chiefly of historic interest, and not important in the causation of 

 edema. In the presence of other factors for the production of edema, 

 however, the amount of fluid in the vessels is important; thus Pearce''^ 

 found that in experimental uranium nephritis hydremia exerted a 

 marked influence on the i)r()du(;ti()n of edcMiia. 



30 Sec Sehmid and Schlayer, Deut. Arch. klin. Med., 1911 (10-4), 44. 

 »' Arch. Int.. Med., l'»OS (3), 422. 



