I 



WOU.NDS OF THE CHEST. 113 



noticed near the wound, but may extend, more or less, over the 

 body, which will have a blown-out appearance. As a rule it occurs 

 by air, during inspiration, entering the pleural sac either through 

 an external wound or a wound in the lung; and, failing to obtain 

 exit by means of its way of entrance, being squeezed by the elastic 

 recoil of the ribs during expiration, into the loose connective tissue 

 which lies open on the wounded surface of the chest wall. In cases 

 of emphysema, the return of the air is prevented by the valve-like 

 action of the wound, or wounds. Emphysema requires little or no 

 special treatment, as it is seldom hurtful. If, as might happen in 

 very rare cases, it interferes Avith the breathing, w^e may let out 

 the air through the skin, at convenient spots, with the knife, or 

 trocar and cannula. 



(3.) Fneuniotliorax or accumulation of air in the pleural sac either 

 from an external opening or from a wound in the lung. This con- 

 dition is brought on in the same manner as emphysema, and it is 

 dangerous, owing to its liability to cause '^collapse of the lung." 

 As the act of inspiration is that of enlargement of the cavity of the 

 chest, which in health reduces the air pressure in the lung and thus 

 causes the lung to become inflated by the in-coming air ; the pre- 

 sence of air in the pleural sac wall, by the resulting pressure on the 

 surface of the lung, directly oppose the performance of this function, 

 and will accordingly give rise to more or less difficulty of breathing. 

 To relieve this serious condition, we may enlarge the external wound, 

 if there be one ; or tap the distended pleural sac with a trocar and 

 cannula, which is an operation tliat demands an accurate know- 

 ledge of the anatomy of the part. " The ohest may be largely 

 opened and yet no collapse take place. This seems most probably 

 to be due to the adhesion of the two smooth moist pleural surfaces 

 to each other " {Ericlisen). When a fair-sized external opening 

 communicates with a wound in the lung, air will rush in through 

 the external opening during inspiration, and be more or less ex- 

 pelled out through it during expiration. 



(4) Pleurisy and (5) imeumonia will respectively follow wounds 

 of the pleura and lung. We can do little to relieve these complica- 

 tions beyond carefully nursing the patient. 



(6.) Emjn/ema, or pus in the pleural sac, is a very serious con- 

 dition which is usually brought on by contamination of blood or of 

 inflammatory discharges which have accumulated in the pleural sac, 

 or by the entrance into it of dirt and other germ-laden material. 

 Treatment should consist of a thorough disinfection of the part 

 by an antiseptic solution (p. 67) and effective drainage, by 

 if necessary, enlarging the external wound, and by making 

 a counter-opening " on a probe passed from the original wound 

 and made to project between two ribs, as the relations of 



8 



