242 ANATOMY AND PHYSIOLOGY 



SPECIAL MODIFICATIONS OF RESPIRATORY MOVEMENTS 



Rapid breathing is called hyperpnea. 



Temporary cessation of breathing is called apnea. 



Labored breathing is dyspnea. 



Dyspnea follows any interference with the interchange of gases 

 in the lungs. It may be caused by diminishing the entrance of 

 oxygen, or by increasing the CO 2 . It is usually due to imperfect 

 circulation in the pulmonary vessels. 



Asphyxia is the condition resulting from a complete cutting 

 off of oxygen, or an excessive increase of carbon dioxide. It may 

 be sudden or gradual, but if unrelieved, ends only in death. 



The change of color noted in the face of one suffering from 

 dyspnea, and still more from asphyxia, is due to the accumulation 

 of carbon dioxide in the blood. 



In Cheyne-Stokes breathing, a period of apnea is followed by 

 respirations which are at first faint and shallow, then gradually 

 increase in depth and rate until they become either normal or 

 exaggerated, when they either cease abruptly or decline to another 

 period of apnea. This may occur many times in succession, but 

 is seldom constant. It is seen in the sleep of a patient with fatty 

 heart, sometimes in the sleep of children apparently well; often 

 in apoplexy. 



Stertorous breathing is characterized by a loud snoring sound; 

 it is unconscious and sometimes labored. 



The production of artificial respiration is attempted by imitat- 

 ing Nature's method. (See p. 238.) By elevating the arms the 

 thoracic walls are spread, the lungs follow, air is drawn in. De- 

 pressing the arms against the thorax presses the walls down, the 

 lungs are compressed, air is expelled. In this manner not only is 

 the air current set in motion in the lungs, but an additional stimu- 

 lus is created by the expanding and subsiding of the lung cells. 

 When expanded they call for expiration to relieve them, and when 

 collapsed they demand inspiration to fill them. This is a physio- 

 logic stimulus which is believed to be constantly felt by the lung 

 tissue in health. 



Internal respiration will be studied under Metabolism. Chapter 

 XVIII. 



