SURGICAL SHOCK 31 



his fatal apnoea, while breathing could be restored 

 on resuming the handhng. 



Deficiency of CO.^ in the blood has another remark- 

 able effect. When the deviation from normal is 

 considerable, there is a tendency for fluid to exude 

 from the plasma into the tissues with great rapidity. 

 This was first demonstrated by Sherrington and 

 Copeman. The plasma therefore becomes con- 

 centrated, and the total volume of the blood is 

 diminished. This further reduces the output of the 

 heart. When this outpouring has become established, 

 transfusion ceases to be of more than temporary 

 benefit. Early in the course of shock, the intro- 

 duction of saHne into a vein will cure ; later on it 

 fails because the fluid merely escapes into the 

 tissues. 



Shock, or a condition exactly analogous to shock, 

 may be induced not only by injury or pain, but also 

 by toxcemia. Whilst Crile was investigating the 

 former condition, Romberg and Passler were making 

 observations on the latter. They found that tox- 

 semic shock was identical in its main features with 

 traumatic shock, and, like Crile, they considered 

 that it was due not to heart failure but to exhaustion 

 of the vasomotor centre after prolonged activity. 

 According to Henderson, however, in both these 

 conditions it is the venous pressure and the venous 

 return to the heart which are subnormal in the first 

 place, and the final fall in the arterial pressure k due 

 not to exhaustion of the vasomotor centre, but to 

 the reduced output of the heart ; this reduced out- 

 put, in its turn, being due not to cardiac weakness but 



