1906.] Obstruction of the Venas Cavce and the Portal Vein. 273 



Oct. 10, 1906. Cat ; weight, 2280 grammes. Morphia, f grain, Ether and 



artificial respiration. 



Pressures. 



Femoral artery. 



External jugular vein. 



Before obstruction 



60 mm. Hg 

 60 



66 mm. Hg 

 54 „ 



60 mm. Hg 

 t 



100 mm. HgS0 4 solution 

 111 



Obstruction to 2 mm 



1 minute later 



112 



112 „ 



113 „ 



205 



221 „ 



206 



185 „ 



174 „ 



170 „ 



130 



110 



105 



5 

 » 



3 

 > ' 



J 



>> 



>) 



1 „ „ 



1 „ 



Complete obstruction 



5 minutes later 



5 „ 



5 „ „ 





5 ,, „ 



5 „ „ 



5 









>J 



Inferior Vena Cava. — On complete ligature of the superior vena cava 

 there is a very trifling and temporary fall of about 10 or 15 mm. MgS0 4 

 solution in the pressure in the inferior vena cava. 



Portal Vein. — Complete occlusion of the superior vena cava or constriction 

 of its diameter to 2 mm. causes a very transitory fall of pressure of about 

 5 mm. MgS0 4 solution in the portal vein. 



The only significance of this slight fall of pressure in the portal vein and 

 inferior vena cava is that it indicates the abstraction of blood from these 

 venous territories and its retention in that of the superior vena cava. 



It is quite apparent, therefore, that the smallest degree of constriction of 

 the superior vena cava, which is necessary to produce any effect upon the 

 venous pressure, will give rise to dropsy. 



3. Effects of Obstruction of the Inferior Vena Cava. 

 (a) Upon the Production of Dropsy. 



In all cases the vein was obstructed just below the heart, between it and 

 the diaphragm. 



Complete Occlusion.-^Qom^lQtQ ligature of the inferior vena cava above the 

 •diaphragm leads to death in a few hours. There is regularly found 15 c.c. 

 •or more blood-stained fluid in the peritoneal cavity. No oedema is found 

 anywhere else. This is exactly the result obtained by Eichard Lower (4), 

 more than 200 years ago, by ligature of the inferior vena cava in the chest, 

 although it is usually misquoted in the text books, which state that he 

 obtained oedema of the hind legs. Antiseptics were not recognised in 

 his day and, so far as I am aware, he left the lung collapsed. In fact, it was 



