1865.] restoring the Life of Warm-blooded Animals, fyc. 363 



Resume". Value of Artificial Respiration. 



Reviewing the whole series of experiments, I am led to the conclusion, 

 and I think it admits of direct demonstration, that artificial respiration, in 

 whatever way performed, is quite useless from the moment when the right 

 side of the heart fails in propelling a current of blood over the pulmonic 

 circuit, and when the auriculo-ventricular valve loses its tension on contrac- 

 tion of the ventricle. 



Break of blood-column. At this point the blood-column is broken : the 

 resistance to the passage of blood is of itself almost overwhelming, while 

 the muscular action is decreasing in power in proportion as the difficulty of 

 propulsion is increasing. 



Obstacle from coalescence of blood-corpuscles. Another obstacle is in 

 the blood itself. It consists in the rapid coalescence of the blood-corpuscles 

 as the motion of the blood ceases. This is so determinate, that within 

 three minutes after its complete cessation, the blood, though still fluid, 

 often fails to be carried, even by a moderately strong stroke, over the lungs. 

 In one experiment the chest of a strong dog was laid open while the animal 

 was under chloroform, and artificial respiration was sustained. Both sides 

 of the heart were acting vigorously, and there was a good arterial current. 

 In the midst of this action, which could easily have been sustained for an 

 hour, the pulmonary artery was suppressed for the space of two minutes 

 and fifty seconds. Then it was liberated, and the ventricle, which was still 

 beating vigorously and gave out a valvular sound, carried the pent-up 

 column into the pulmonary vessel ; but there was no circuit. The lung 

 was somewhat congested, and the capillaries were blocked up so as to resist 

 an impulse which, increased by galvanism, was more active for some minutes 

 after the liberation of the artery than it had been previously. 



Obstruction from coagulation of blood. The last obstruction is the co- 

 agulation of the blood ; but as this does not, as a general rule, occur (in 

 cases where the blood-vessels are not opened) within twenty minutes, and 

 often not within an hour, it may be considered a secondary difficulty, 

 though naturally fatal to success, according to our present knowledge, when 

 it has taken place. 



Modes of applying Artificial Respiration. 



Regarding the modes of applying artificial respiration, and the time, the 

 facts are briefly as follows : 



1. It is unnecessary and even injurious to employ it so long as there is 

 any attempt at natural respiration*. 



2. Before employing it, the patient should be placed with the head 

 slightly lowered, a position which will largely assist the right ventricle in 

 any feeble effort it may be making to propel a current of blood into the 

 pulmonic circuit. 



3. It is of the greatest importance that the air conveyed into the lungs 



* On this poi'it see observations 20 and 21 in the Experimental Part. 



