RESPIRATION 435 



tion. A deficiency in the amount or the quality of the hemoglobin is usually 

 attended with more or less dyspnea. 



Asphyxia. If the state of the blood observed in dyspnea be exaggerated 

 that is, if the increase in the percentage of carbon dioxid become more 

 marked the respiratory movements become more laborious. A con- 

 tinuance of this changed composition of the blood eventuates in death. 

 Before this occurs the individual exhibits a succession of phenomena, to the 

 totality of which the term asphyxia is given. 



Asphyxia may be caused: (i) By a sudden interference with the entrance 

 of oxygen into and the exit of carbon dioxid from the blood, as in drowning, 

 occlusion of the trachea from any cause, double pneumothorax, etc. (2) 

 By confinement in a small space the air of which speedily undergoes a loss 

 of oxygen and an accumulation of carbon dioxid. In the first instance 

 death may occur in a few minutes; in the second instance it may be postponed 

 several hours or more, the time varying with the size of the space. 



The succession of phenomena presented by an individual in the asphyxi- 

 ated condition is as follows: Increased rate and depth of the respiratory 

 movements, passing rapidly from hyperpnea to dyspnea, with an active con- 

 traction of all the muscles concerned in respiration, ordinary and extraor- 

 dinary; a blue, cyanosed condition of the face from the rapid accumulation 

 of carbon dioxid and disappearance of the oxygen of the blood; a diminution 

 in the depth of inspiration and an increase in the force and extent of ex- 

 piration, followed by general convulsions; collapse, characterized by un- 

 consciousness, loss of the reflexes, relaxation of the muscles, a weak action of 

 the heart, a disappearance of the pulse, and death. As shown by observation 

 of the circulatory apparatus in artificially induced asphyxia, there is primarily 

 an increase in the activity of the heart, soon followed by retardation; a rise 

 of blood-pressure in the early stages and a fall to zero after collapse has set 

 in. The retardation and final cessation of the heart, as well as the rise of 

 the blood-pressure, are to be attributed to stimulation of the cardio-inhibi- 

 tory and vaso-motor centers from the accumulation of the carbon dioxid. 

 With the exhaustion of the nerve-centers, there is a general relaxation of the 

 skeletal muscles, the cardiac muscle, a fall of the blood-pressure, and dilata- 

 tion of the pupils. 



The Cheyne-Stokes Respiration. A modification of the respiratory 

 movements characterized by periods of rest alternating with periods of 

 activity was described in 1818 and in 1854 by the two writers whose names 

 bears The periods of rest vary in duration from twenty to thirty seconds 

 the periods of activity from thirty to sixty seconds and may include I 

 twenty to thirty respiratory movements. 



Each period of rest of the respiratory mechanism is closed by the appear- 

 ance of a slight shallow respiratory movement, which is immediately fc 

 lowed by a second, slightly deeper, and this in turn by a third, a four 

 fifth, and so on, each becoming deeper than the preceding until a certain 

 maximum is reached, after which, each succeeding movement gradua 

 diminishes in depth until finally the movement becomes imperceptible ai 

 new period of rest supervenes. A graphic representation of the C 

 Stokes type of respiration is shown in Fig. 201 This type of respiration 

 frequently an accompaniment of certain pathologic conditions, eg., uremic 

 states, cerebral hemorrhage, heart diseases, arteriosclerosis, etc, though no 



