32 SURGICAL SHOCK 



to inadequate entry of blood along the venae cavae. 

 Both Crile and the German observers laid great stress 

 on the fact that stimulation of a sensory nerve fails 

 to induce the usual rise of blood-pressure, by reflex 

 arterial constriction, when advanced shock is present, 

 and they interpreted this as due to exhaustion of the 

 vasomotor centre ; according to Henderson, the 

 truth is that the centre is already sending out its 

 maximum of impulses, but that the pressure is low 

 notwithstanding, because there is so little blood 

 actually circulating. He remarks that if the arteries 

 were paralysed, an intravenous injection of sahne 

 would not raise, as it frequently does, the arterial 

 blood-pressure to normal, "because the blood would 

 run out through the capillaries too easily for any 

 pressure to be developed." 



There is experimental evidence that the venous 

 pressure is not regulated by the nervous system, but 

 rises and falls with the amount of CO., in the blood. 

 Adrenalin has no influence on it. The carbon di- 

 oxide acts partly by influencing the tone of the 

 muscle in the vein wall and in the supporting 

 external tissues, and partly by controlhng the escape 

 of fluid by osmosis. 



The measures which he used to prevent shock 

 were to diminish the loss of carbon dioxide by keep- 

 ing the artificial respiration very slow, and using a 

 long tube attached to the trachea, so that a good 

 deal of the expired air was in-breathed again. To 

 relieve shock he adopted three measures : — 



I. Pouring warm saline saturated and bubbUng 

 with CO2 into the abdomen, and closing the cavity. 



