PNEUMOTHORAX. 293 



characteristic sign of pyo-pneumothorax is, that the limits of the dul- 

 ness change as the patient alters his posture. "When he lies upon his 

 back, the sound in front may be full, down to the border of the lower 

 libs ; if he stands up, the dulness may extend far up his chest. 



Auscultation. When there are both air and liquid in the pleural 

 sac, a distinct metallic splashing (like the sound of water, shaken up 

 in a half-filled bottle) is often audible, even without putting the ear to 

 the chest, whenever the patient suddenly changes his position, or when 

 he is shaken (succussion). JSTo vesicular respiration is to be heard, 

 which, in conjunction with the full percussion-sound, is a symptom of 

 great significance. In its stead, we hear metallic sounds and am- 

 phoric breathing, and especially the metallic rattling (the tintement 

 metallique) sounds which are also heard over large vomicae with smooth, 

 regular, concave walls. We are not at liberty to infer, from the exist- 

 ence of metallic sounds, that air flows into and out of the pleural sac, 

 as such sounds may also arise when the communication is closed, the 

 murmurs generated in the lung giving a metallic reverberation. While 

 the above signs arise with great completeness and harmony, in most 

 cases where the air is capable of free movement in the cavity of the 

 pleura, after perforation of a vomica, so that the affection is then very 

 easy of recognition, many of them may be absent when the pneumo- 

 Ihorax is incapsulated. If the space containing the air be too small, 

 or too irregular in shape, to be capable of assuming a regular bulbous 

 form under pressure of the air and exudation, no metallic sounds are 

 heard, either upon percussion or auscultation. The most constant and 

 trustworthy sign of incapsulated pneumothorax is a full percussion- 

 sound, with absence of respiratory murmur. 



Besides this, in a few cases, in which, after bursting of an empyema 

 into the lungs, the cavity containing the air and effusion was extreme- 

 y irregular, I have been able, by laying my hand upon the thorax, 

 to feel the liquid wash against the anterior side of the chest, when the 

 patient raised himself quickly and with energy. 



DIAGNOSIS. It is only when we are suddenly called to the bedside 

 of a patient, or when we receive him into hospital in such a condition 

 of suffocation that he is unable to give any account of his previous ill- 

 ness, that pneumothorax is liable to be confounded with emphysema. 

 In all other instances, the rapid development of the dyspnoea in pneu- 

 mothorax and its extremely gradual establishment in emphysem? 

 place the matter beyond a doubt. 



In the less obscure cases we may rely upon the following tokens. 

 1. In emphysema, both sides of the chest, in pneumothorax but one is 

 dilated (emphysema is bilateral, pneumothorax is almost always mono- 

 lateral). 2. In emphysema the intercostal spaces are shallow furrows 



