SHOCK 295 



tion in the stagnant blood of incompletely oxidized metabolic products, 

 which raise the hydrogen-ion concentration of the blood, and produce 

 a further relaxation of the muscle fibers in the vessel walls. That acid 

 has such an effect is well known (page 937). Dilatation or atonicity thus 

 progressively increases and is meanwhile further encouraged by the de- 

 privation of oxygen, for it has been shown that isolated artery strips do 

 not exhibit their usual tonicity when deprived of oxygen. 



Treatment 



Whatever may be the cause of the atony of the capillaries and 

 venules in shock, the existence of this condition indicates that the most 

 hopeful line of treatment is to cause the vessels to reacquire their tone. 

 It will be remembered that in gravity shock in a rabbit recovery may 

 be accomplished by the application of a tight binder to the abdomen, 

 or by placing the animal in a head-down position. Such measures ap- 

 plied in the case of man have not, however, been found of much value. 

 Pressure thus applied is evidently not brought to bear sufficiently on 

 the atonic vessels. Cannon has therefore made the interesting suggestion 

 that a hopeful procedure may consist in injecting directly into the ab- 

 domen a saline solution containing pituitrin, a hormone which, it will 

 be remembered, acts directly on involuntary muscle fiber. 



Two other methods have been advocated for the treatment of shock 

 namely, saline or blood transfusion and injection of epinephrine; but 

 neither method has proved of practical value. Epinephrine injections 

 do indeed temporarily raise the arterial blood pressure, but the subse- 

 quent condition of shock is possibly worse than that originally present. 

 After the injection of blood or saline solution containing gelatin or 

 mucilage, the blood pressure, although temporarily raised, very quickly 

 falls again. In this regard surgical shock differs from the shock follow- 

 ing severe hemorrhage, in which, as explained elsewhere, recovery of the 

 blood pressure as well as of the general condition of the animal can 

 be accomplished by transfusion with blood or with saline solution con- 

 taining mucilage or gelatin. This would indicate that there is some 

 essential difference between these two forms of sjioek (see page 140). 

 The only treatment of avail appears to be to keep the patient warm and 

 to remove causes of excessive pain. 



Causes of Secondary Symptoms 



It remains to consider the cause of some of the secondary conditions 

 developing in shock namely, the disturbances in sensation and motion 

 and the fall in body temperature. All of these are undoubtedly depend- 



