288 RESPIRATION 



that fluid is supplied ; and the great thirst which results from loss 

 of blood is an expression of the need for fluid. But time is required 

 for this natural process of recuperation, and meanwhile the patient 

 may die. 



Fluid may be supplied quickly by the intravenous injection of 

 Ringer's Solution, but this plan is rather ineffective, since the 

 injected liquid leaks out from the vessels quickly. Bayliss there- 

 fore introduced his now well-known gum-saline solution for use 

 in cases of loss of blood and similar conditions.^^ The gum does 

 not leak out at all readily from the vessels, and in virtue of the 

 osmotic pressure which it produces it keeps the salt solution from 

 leaking out. The gum thus plays the same part in this respect as 

 the proteins of the blood plasma, but is free from the occasional 

 toxic properties of the proteins in blood transfused from another 

 person, although it seems to be sometimes not free from disadvan- 

 tages. It might seem at first sight as if the injection of gum saline 

 must, other things being equal, be very inferior in its effects to 

 transfusion of blood, since there is no haemoglobin in the salt solu- 

 tion. But unless the loss of blood has been enormous there is no 

 great need for haemoglobin. Increased rate of circulation will 

 make up for diminished power of the blood to carry oxygen and 

 CO2, as explained more fully on page 293. 



The conditions known as "wound-shock," "surgical shock," 

 "anaesthetics shock," and shock from burns, have given rise to 

 much discussion and investigation. When "shock" is fully de- 

 veloped, the arterial blood pressure is very low, the pulse feeble, 

 the lips and skin leaden colored, and the breathing shallow and 

 often rapid, or sometimes periodic. It appears at present as if this 

 general condition can be brought about in several different ways ; 

 and Yandell Henderson's investigations have thrown a clear light 

 on certain of the causes of shock. It will be convenient to consider 

 these first. 



He showed in the first place that a condition of shock can be 

 brought about in animals by continued excessive ventilation of the 

 lungs. This of course greatly reduces the CO2 in the arterial 

 blood, thus producing a state of alkalosis. The response to this ib 

 slowing of the circulation, and consequent great anoxaemia, as 

 already explained. The slowing of the circulation tends, of course, 

 to diminish the alkalosis in the tissues, but only at the expense of 

 producing most formidable anoxaemia. The alkalosis is also com- 



"Bayliss, Intravenous Injection in Wound Shock, 1918. 



