Respiratory Disturbances. 39 



with the respiratory movements, as in case of rupture of the 

 diaphragm, the principal muscle of respiration, in case of its' 

 immobility or when it is forced forward by flatulence, in case of 

 marked pressure from without upon the chest walls (animals 

 standing pressed together in railway cars), or in case of pressure 

 upon the lungs by large fluid collections in the chest cavities. 

 Failure of respiratory movement may also occur from nervous 

 origin (pressure upon the brain,, paralysis of the vagi, spasm of 

 the bronchial muscles). Premature separation of the placenta or 

 compression of the umbilical cord in the maternal canal prevents 

 ox}gen convection to the foetus. 



Furthermore, passive congestion of the lungs, interference 

 with the emptying of the pulmonary veins and haemic changes in 

 which the blood corpuscles have lost their ability of taking up 

 oxygen (carbon monoxide poisoning) render dift'usion of the 

 gases so difficult that the same result of lowering oxygenation 

 arises, and the respiratory disturbance eventually advances to the 

 stage of sufifocation. The presence of irrespirable gas and the 

 reduction of oxygen in the air of an inclosed space (instead of 

 20.8 per cent., perhaps only 2 to 3 per cent.) act in a similar 

 manner. 



In one or other of such a variety of ways asphyxia may be 

 the termination of a number of diseases and is the commonest 

 cause of death. It is usually accompanied by the symptoms 

 of dyspncea (17 Smirvoia, from wviw, difficult breathing, shortness of 

 breathing), labored respiratory movements (sufi'ocative dyspnoea), 

 marked increase in the cardiac movements, spasmodic twitching of 

 the general musculature and loss of consciousness. Toward the close 

 the respiratory movements become irregular, sometimes intermit 

 and suddenly cease, the inspirations occasionally becoming very 

 deep (terminal respiratory movement) ; and the spasms weaken 

 the cardiac action (true asphyxia, actual pulselessness, from 

 a privitive and 6 (7(pvy/j.6s, the pulse). When the diminution in 

 oxygen is gradual in its onset these symptoms appear less promi- 

 nently ; but as the tissues degenerate from the. insuflicient supply 

 of oxygen (fatty degeneration of the heart, liver, kidneys) and 

 as the respiratory nervous center loses its excitability, the patient 

 dies from gradually increasing loss of consciousness and cardiac 

 failure. According to the rapidity of onset of the fatal end and 

 the causes of the asphyxia, the post-mortem findings present dif- 

 ferent pictures. In addition to the local changes due to strangu- 



