■i III. M TRITION OP l Hi Hi Mil 165 



The practical question, in so far as resuscitation of the heartbeal is 

 concerned, i^ therefore, //""■ can wt get tl>< n< >■> ssary fluid under pt 

 sure into II" beginning of II" aorta? Even if we were to transfuse fluid 

 under considerable pressure into the aorta through the carotid artery, 

 it would mainly follow tin- large vessels leading away from the ln-art. 

 only a Fraction ofil reaching the beginning of the aorta. To compel the 

 iluiil to pass towards the hearl we musl introduce some obstruction to 

 its passage peripherally. This can be done by the injection of a consid- 

 erable dose of epinephrine I adrenaline in normal saline Bolution through 

 tin' needle of a hypodermic syringe inserted into the tubing leading 

 from the burette or pressure bottle to the cannula in the carotid arte 

 An the perfusion fluid is running in, the epinephrine injection is quickly 

 made, artificial respiration and cardiac massage being meanwhile prac- 

 ticed. In the majority of animals it will be found that complete res- 

 toration of the normal blood pressure can be effected by this method, 

 [ndeed by performing the resuscitation under aseptic conditio! s, some 

 animals may be permanently resuscitated so far as the circulation is 

 concerned, although the nervous structures, even after a few minutes 

 of "death," never reacquire their normal condition. 



The epinephrine acts mainly by constricting the small arterioles and 

 thus directing the bloodflow towards the heart, bul partly also by a direct 

 stimulating action on the cardial- muscle. It does not, however, con- 

 tract the coronary vessels; on the contrary, it is said to cause tl 

 slightly to dilate. 



THE RELATIVE IMPORTANCE OF THE VARIOUS CONSTITUENTS 



OF THE PERFUSION FLUID 



We can study the chemical conditions necessary for resuscitation 

 of the heartbeat by observing the beal of an artificially perfused hearl 

 while solutions of differenl chemical composition are being perfi 

 through the coronary vessels. At the outset we are im] i with the 



fact that for successful resuscitation the organic constituents t the 

 nutrient fluid are of trivial importance compared with the inorganic 



constituents. "With a solution containing the proper proportion of in- 



janic salts, and of course an adequate supply of oxygen, the heart 

 o\ a rabbit, for example, may he made to continue beating i'"r - 

 days, h is tine that it will heat longer if some of the organic con- 

 stituents of the blood plasma, particularly carbohydral 

 hnt on the inorganic constituents aloni ability to beal a truly 



remarkable. 



