480 WOUNDS OP THE PLEURA AND THORACIC CAVITY. 



persists. Where continual irrigation is unattainable, the wound 

 must be rinsed out carefully every hour or two with a disinfectant. 

 Similar methods of examination and checking haemorrhage are 

 applicable to wounds extending under the shoulder. Provision must 

 be made for free exit of discharge, and incisions, counter openings, 

 &c., combined with effectual irrigation, adopted as above indicated. 



(2.) WOUNDS OF THE PLEURA AND THORACIC 

 CAVITY. 



Punctured or penetrating wounds of the chest are usually caused 

 by thrusts with the bayonet, lance, or sabre ; in war by projectiles ; 

 by falling on harrow teeth, or on the rider's spur ; in oxen by horn- 

 thrusts, by splinters of wood, or by the aspirating needle used to 

 drain the pleural sac. Such wounds extend through the pleura 

 costalis, and even injure the thoracic or abdominal organs. Besides 

 the dangers of bleeding and infection, such injuries may lead to 

 pneumothorax, hemothorax, pleurisy, and pneumonia. 



(1) Pneumothorax. Air may enter the pleural sac either from 

 without, or from the lung. As soon as a considerable wound pene- 

 trates the pleura costalis, the distended elastic lung generally 

 collapses, air is drawn in through the opening in the pleural sac, 

 and breathing ceases in the affected portion of lung. The walls 

 of the chest continuing their respiratory movements, however, the 

 air streams outward during expiration, and re-enters during 

 inspiration. Should the opening in the thoracic wall be partly or 

 entirely closed during expiration, emphysema results from the 

 retiring air being forced into the loose connective tissue in the neigh- 

 bourhood of the wound. Injury to lung or a bronchus also causes 

 pneumothorax, usually attended with severe bleeding and collapse 

 of the affected portion of lung. 



Air in the pleural sac is not necessarily fatal, so long as both lungs 

 do not collapse, though in the horse such a complication is to be 

 feared on account of the cribriform structure of the mediastinum 

 behind the heart. It is reabsorbed in a comparatively short time, 

 as has long been known in man ; and more recently been demon- 

 strated in horses by the experiments of Trousseau, Leblanc, and 

 Perosino. Perosino opened the pleural sac in a horse between the 

 10th and 11th ribs, and allowed air to enter through a tube until 

 the difficulty in breathing threatened death from suffocation ; but, 

 on the evening of the day of experiment, all untoward appearances 

 had vanished. Pneumothorax is, nevertheless, a very grave con- 



