

PATHOLOGICAL VARIATIONS IN THE RESPIRATORY MOVEMENTS. 211 



extent of 5 or 6 cu. cm. on one or both sides. When the apices are affected, as 

 occurs so frequently in cases of tuberculosis of the lungs, the subnormal expansion 

 in the upper parts of the thorax is a characteristic feature. Retraction of the 

 intercostal spaces, the ensiform process, and the lower insertions of the ribs occurs 

 during marked inspiratory rarefaction of air in the thorax, such as may take 

 place in the presence of laryngeal stenosis. If this phenomenon be confined princi- 

 pally to the upper parts of the thorax, it shows that the subjacent part of the 

 lung is diseased and capable of little expansion. 



In persons suffering from chronic, advanced disease of the respiratory organs, 

 without impairment in the activity of the diaphragm, the insertion of the latter 

 manifests itself on the outer surface of the body by a shallow groove (Harrison's 

 groove) , passing horizontally outward from the ensiform cartilage, and due to the 

 marked retraction. 



The period of inspiration is lengthened in persons suffering from constriction 

 of the trachea or larnyx; that of expiration in those who must call into play all 

 the expiratory muscles, by reason of an emphysematous condition of the lungs 

 (Fig. 72, II). Occasionally, in emphysematous subjects, a short expiratory effort 

 precedes the inspiration. 



Changes in the Rhythm of the Movements. All disturbances of the respiratory 

 apparatus of any degree of magnitude will produce an increase in the frequency 

 or depth of the respirations, or both together. This phenomenon is termed dysp- 

 nea. The possible causes of dyspnea are various: i. Restriction of the respira- 

 tory exchange of gases in the blood, as a result of (a) diminution of the respiratory 

 surface (pulmonary diseases) , (6) contraction of the air-passages, (c) diminution in 

 the number of red blood-corpuscles, (d) disturbances in the mechanism of respira- 

 tion (affections of the respiratory muscles and their nerves, painful affections of 

 the thoracic walls), (e) weakness in the circulation, especially the lesser circulation, 

 principally as a result of various cardiac affections. 



2 . Febrile conditions are a further cause of increase in the frequency of respira- 

 tion. The febrile blood heats the respiratory center in the medulla oblongata, 

 and thus incites dyspneic respiratory movements up to from 30 to 60 in the minute 

 (heat-dyspnea). If the carotids of animals be placed in hot tubes, the same result 

 is produced. Under the influence of hysterical irritability, a nervous pathological 

 increase in the respiratory rate may be produced in rare cases. Respiratory pauses 

 of considerable duration are uncommon, but they may occur (in one patient with 

 cardiac and renal disease a pause of thirty-seven seconds was observed during sleep). 



A remarkable change in the rhythm of respiration is known as Cheyne-Stokes' 

 breathing. This manifests itself as a suffocation-phenomenon in affections that 

 alter the normal supply of blood to the brain, or that change the composition 

 of the blood, for example, cerebral affections, cardiac diseases, or uremic intoxica- 

 tion. Under such circumstances pauses of from one-half to three-fourths of a 

 minute alternate with series of from 20 to 30 respirations, likewise extending over 

 from one-half to three-fourths of a minute. The respirations of a single series are 

 first superficial ; they then become deeper and dyspneic, and then again more super- 

 ficial. After this a pause occurs, and at this time the eyeballs roll, the pupils are 

 contracted and do not react, and the blood-pressure falls. In severe cases complete 

 loss of consciousness, analgesia, abolition of the reflexes, and even inability to 

 swallow, rarely, toward the end of the pause, also muscular twitchings have been 

 observed during the pauses. When the respiratory movements commence again, 

 the pupils become larger and reactive. It has often been observed that conscious- 

 ness, lost during the pause, has been partially regained whenever the respirations 



In agreement with Rosenbach and Luciani the cause of Cheyne-Stokes' 

 breathing is referred to variations in the irritability of the respiratory center, 

 which reaches its lowest point during the pause. Luciani compares the phe- 

 nomenon with that of the periodically grouped heart-beats. He observed i 

 set in after injury to the medulla above the respiratory center, after the apnea 

 in animals profoundly poisoned with opium, and finally in the last stage of as- 

 phyxia attending respiration in a closed space. 



Cheyne-Stokes' respiration is most readily explained by assuming the pau 

 to be a period of asphyxia, and the series of respirations to be agonal. Under 

 the reviving influence of the latter, the respiratory center recovers from the pre- 

 vious state of exhaustion. 



During hibernation this form of breathing is normal in the dormouse, 

 hedge-hog, and the alligator. If frogs are kept immersed in water, or if the 



