196 



Scientific Proceedings (68). 



experiments indicate rather that there is a special sequestration 

 of the blood in the capillaries of the liver, but further that the 

 increase in size of the liver, coupled with the diminution in the 

 size of the intestines, cannot alone account for the diminished 

 arterial blood pressure. 



The crucial factor concerns the fact that after the relief of the 

 obstruction to the flow of blood through the inferior vena cava 

 there occurs, even after a more or less complete restoration of the 

 arterial blood pressure, a progressive fall until death. This 

 progressive fall can only be a consequence of some change in the 

 walls of the vessels primarily affected by the occlusion of the 

 inferior vena cava, namely, the capillaries and small venules. It 

 is quite obvious, inasmuch as the total amount of blood circulating 

 is a constant quantity, that an over filling of the vessels on the 

 venous side of the most peripherally situated vessels possessing 

 a muscular wall must be accompanied by diminished total sec- 

 tional area of the vessels on the arterial side of the last vessels 

 possessing power of active resistance to the volume of blood 

 contained in them. All experiments indicate that the lumen of 

 the smaller arteries and arterioles are diminished. The pressure 

 laws of vaso-motor adjustment under conditions of reduced 

 arterial blood pressure, the comments of Henderson, the findings 

 of Muns, the results of the perfusion experiments of Morison and 

 Hooker, all indicate that the arterioles and smaller arteries possess 

 a diminished lumen in shock. We have demonstrated that there 

 is at least no greater response to the injections of adrenalin in 

 shock than before shock has been induced. This fact explains 

 the failure of any great increase in volume of the combined intra- 

 abdominal organs in shock. 



In other words, our experiments of mechanically induced shock 

 indicate that a mechanical distension of a certain degree and length 

 of time is able to cause an alteration of the normally present 

 contractility of the capillaries; in other words, of their tone, in 

 virtue of which they lose the power of emptying the increased 

 quantity of blood which they contain through the heart into the 

 arterial side of the circulation, a power which they still preserve 

 after either shorter periods of over-distention or distention of 

 lesser degrees. 



