428 ILLINOIS STATE ACADEMY OF SCIENCE 



It is evident, then, that there is a close relationship 

 between the clinical condition of cardiac patients and the 

 vital capacity of the lungs. If the maximnm respiratory 

 exchange be known, one can tell with considerable accur- 

 acy what the functional condition of the patient probably 

 is. Decompensated patients show a low vital capacity 

 which rises with improvement, and the extent of the in- 

 crease corresponds to the degree of clinical improvement. 

 When the vital capacity remains constant^ the patient's 

 condition remains unchanged. A rapidly rising vital ca- 

 pacity after a period of decompensation indicates a fa- 

 vorable prognosis, while a failure to rise more than a 

 small amount or the maintenance of a continuously low 

 vital capacity is indicative of a less favorable outlook. 

 Slight changes in the vital capacity of ambulatory pa- 

 tients may be of a great significance. Peabody and Went- 

 worth illustrate this by the case of a stained glass worker 

 "who has a double mitral disease and auricular fibril- 

 lation. When in his best physical condition, his vital 

 capacity is 2,600 c. c, or 65 per cent of the normal. At 

 such times, he can walk slowly without discomfort, and 

 can do a little light work. May 1, 1916, he came 

 to the outdoor department, stating that he felt poorly 

 and found that he was getting out of breath more 

 easily than usual. His vital capacity was found 

 to have decreased to 2000 c. c, or 50 per cent. He was 

 given digitalis and told to go to bed for a week. At the 

 end of this time on May 19, 1916, he reported again, to 

 say that he was as well as before his upset, and his vital 

 capacity had risen to 2600 c. c, ' ' 



Determination of the vital capacity has been of service 

 in correcting false impressions derived from the histories 

 of certain patients. Neurotic women may complain of 

 shortness of breath, which is apparently out of propor- 

 tion to the physical findings in the examinations of the 

 heart, and the vital capacity may be so high as to afford 

 no explanation for such tendency to dyspnea. When the 

 suspicion exists that the sympton is due to nervous- 

 ness, the patient may be tested by walking rapidly and 

 by climbing stairs. No abnormal dyspnea will result 

 and the determination of the vital capacity will serve to 



