298 DISEASES OF THE PLEURA. 



bowel lying behind. Each act of inspiration diminishes the area by 

 lowering of the diaphragm and lung. Contraction of the left lung 

 enlarges it, while emphysema and hypertrophy of the left ventricle 

 reduce it. It is especially important in distinguishing between 

 pneumonia of the left side and a pleuritic effusion ; for nothing but 

 a large pleuritic effusion can so depress the diaphragm as to com- 

 pletely deaden the tympanitic sound of this region. 



4._p. 284. 



The indications for paracentesis have of late been more fully laid 

 down by Kussmaul, Bartels, and others. One of two procedures 

 may be adopted : either simple evacuation by puncture of the tho- 

 racic cavity with subsequent closure, or else free incision kept per- 

 manently open. 



Puncture with exclusion of the air is indicated 1. When an ex- 

 cessively large effusion causes alarming dyspnoea, displaces the heart 

 and mediastinum, and is refractory to other means of relief ; 2. As 

 a means of determining the quality of the exudation ; 3. After abate- 

 ment of the acute inflammatory stage, to remove large non-purulent 

 serofibrinous exudations, which have shown no disposition to reab- 

 sorption in spite of a treatment of several weeks' duration by other 

 means. Such an effusion, it is true, may subside spontaneously at 

 a later period, even months or years afterward ; but the operation 

 is not a dangerous one, and there is danger that a tardy reabsorp- 

 tion may leave the compressed lung permanently impervious to the 

 air. During the operation the entrance of air into the chest must 

 be guarded against, because, in the presence of air, a non-purulent 

 exudation acquires the pernicious qualities of a purulent one. 



Free incision through an intercostal space, and establishment of 

 a permanent fistula with free access of the air, is indicated in em- 

 pyema as soon as the purulent nature of the effusion has been ascer- 

 tained. The operation should be prompt ; for there is no chance 

 of a reabsorption of the pus, and the continued presence of the 

 thickened, cheesy exudation exposes the patient to the risks of con- 

 sumption by fever, or to the dangers of a subsequent tuberculosis. 

 It is only when the lung retains its distensibility that complete re- 

 covery can take place after the fistula has closed. When it is other- 

 wise, the thorax contracts or the fistula remains open. The opera- 

 tion is not contraindicated even by the presence of phthisis, since 

 life may be prolonged by it even then. For details we refer to the 

 appropriate works on surgery. 



