Etiology. Symptoms. Diagnosis. 91 



and may disappear completely as soon as the primary affection 

 is relieved. It is therefore of minor clinical importance. Ac- 

 cording to the primary disease simple bloating of the lungs 

 may be diffused over both lungs (volnmen auctum pulmonnm, 

 Krehl) or it may be confined to portions of the lungs (emphy- 

 sema pulmonnm alveolare vicarians). 



Etiology. Diffuse acute bloating of the lungs is a regular 

 concomitant to diffuse* microbronchitis. It is seen in the course 

 of pleurodynia (see page 87) ; also in long-lasting convulsive 

 cough, in long-continued strong inspiration and expiration as 

 it is seen in certain diseases of the air passages or in a pro- 

 tracted agonal struggle. 



Circumscribed acute bloating of the lungs develops if the 

 bronchi of a certain territory become narrowed or if certain 

 parts of the lungs have l)ecome obstructed. In the former 

 case the corresponding portions become emphysematous ; in the 

 latter case, neighboring areas. 



Diffuse, as well as circumscribed emphysema develops 

 partly on account of overstretching of the alveoli, partly on 

 account of the fact that the escape of air out of the alveoli 

 is more or less interfered with in certain diseases of the air 

 passages, hence more and more residual air remains in the 

 alveoli. 



Symptoms. Aside from the symptoms of the primary dis- 

 ease there is in diffuse acute bloating of the lungs, an increased 

 resonant percussion sound over the lower and posterior pul- 

 monary margins and a displacement backwards of the posterior 

 inferior pulmonary border, which may be extensive enough so 

 that the posterior inferior pulmonary border reaches to the 

 costal arch (authors' own observation). The percussion sound 

 is more rarely affected in circumscribed acute bloating of the 

 lungs, i. e., Avhen a larger lung territory has become affected. 

 The respiratory sounds vary in both forms, according to the 

 nature of the primary affection; if larger pulmonary territories 

 have been obstructed one hears intensified vesicular breathing 

 over the emphysematous portions. 



Bloating of the lungs decreases the expansion of the lungs 

 in direct proportion to its extent because severe bloating, which 

 has existed for any length of time, will decrease the elasticity 

 of the pulmonary tissue. Bloating, however, will disappear 

 without leaving any trace, if the primary disease leads rapidly 

 to recovery, but chronic alveolar emphysema with atrophy of 

 the interalveolar septa will develop when the primary disease 

 exists for a longer period of time. 



Diagnosis. If the percussion sound is changed in the 

 manner indicated above and if primary diseases as mentioned 



