The Thorax 119 



with his finger until he felt the heart, and the animal recovered. 

 Theoretically, when only one sac is opened, sufficient for air to gain 

 entry, and the opposite sac remains intact, the condition is not incom- 

 patible with life, because unilateral respiration would still be pos- 

 sible. But, though the dog has two separate and distinct pleural 

 sacs, they are separated only by a thin diaphanous mediastinum, 

 and as a matter of fact, as has been established by all those who 

 have experimentally opened the chest-wall, air apparently reatUly 

 passes through this membrane and causes the collapse of the ad- 

 joining lung. At any rate, it has been found impossible to open 

 either sac to any extent without making provision for the main- 

 tenance of respiration by artificial means, and this involves the 

 temporary introduction of a tube into the trachea and the employ- 

 ment of bellows. 



The other great danger lies in septic infection, which is very 

 apt to take place. In this respect, the pleura offers a striking con- 

 trast to the peritoneum, which possesses a well-known relative 

 immunity to infective processes. Sherman believes that this may 

 be due to the fact that the pleura does not, like the peritoneum, 

 offer pockets or recesses in which an infection may be confined, 

 and that constant motion incident to respiratory and cardiac ac- 

 tion tends to disseminate pathogenic microorganisms. Were it 

 possible to drain the pleura, sepsis might be combatted, but inas- 

 much as drainage of the pleura inevitably results in collapse of 

 both lungs, no steps in this direction can be taken. 



Symptoms and Diagnosis. Wounds of these parts are difficult 

 of both diagnosis and prognosis. If hemoptysis ensues it is in- 

 dicative of wounding of the lung. When air is entering a pleural 

 sac in small quantities, the fact is easily recognized by the sound 

 at every act of respiration. In any case, respiration is usually 

 greatly accelerated, and this is particularly true when hemothorax 

 exists. Penetrating or deep wounds of the chest-wall should 

 never be probed for fear of bringing about pneumothorax and in- 

 troducing microorganisms. Prognosis must always be guarded. 



Treatment. Penetrating wounds of the thorax should be 

 closed as quickly as possible by suturing and application of anti- 

 septic bandages. No attempt should be made to evacuate hem- 

 orrhagic exudate in the pleural sac because it soon coagulates, and 

 is gradually absorbed even if present in considerable quantity. 



