348 Pulmonic Interstitial Emphysema 



ring of alveoli, which arises inevitably with the compensatory alveolar emphy- 

 sema occurring by reason of the fact that the surviving lung substance has to 

 enlarge to fill the space vacated by the ablated part. PIE has not so far been 

 presented as an important postoperative problem in lobectomies and pneu- 

 monectomies. So, pulmonic local overstrain, arising in an atelectasis-engen- 

 dered alveolar ectasia, when augmented by contributory factors, conditions 

 PIE. In this light, atelectasis is a menace. All possible means should be taken to 

 diagnose it and be on the watch for its offspring, PIE, which makes itself known 

 clinically by the airblock syndrome, and in other ways. 



Survey of the Literature for PIE and Its Sequelae 



A survey of pathological and clinical literature shows that there is reason to 

 conclude that PIE was present in many cases where, to the attending physi- 

 cians, it was occult; and, indeed, to believe that it is much more prevalent than 

 is supposed. The evidence is direct and indirect. The direct, or pathological, 

 evidence is obtained at autopsy when bubbles of air are disclosed in the inter- 

 stitial tissues of the lung. The indirect, or clinical, evidence is of several sorts. 

 Important is the roentgenographic display of the effect of air in the medi- 

 astinum, which must have originated from a PIE; and also of the result of 

 air in the pleural cavity, for this may ultimately have come from a PIE. Actual 

 proof that there was air in the anterior mediastinum would be afforded by 

 withdrawing it from the location with a hollow needle. The presence of sub- 

 cutaneous emphysema would probably implicate the mediastinum as the 

 source, and ultimately the lung interstitium. The symptoms and signs point- 

 ing to the existence of airblock would be important indicators of PIE and its 

 sequelae. The following resume of published clinical reports was prepared by 

 one of us (M.T.M.) We shall first take up cases in which it seems reasonable to 

 believe that local overstrain was the important causal factor, and where the 

 air-pervious region probably arose as a consequence of an atelectatic condition. 

 The survey makes no pretension to completeness. It is impossible here to men- 

 tion all the clinical instances of this kind in the literature, and the references 

 given will be only a few of the many that might be cited. 



We feel that this study brings home strongly the great useftdness of re- 

 porting clinical and pathological observations, even though their signifi- 

 cance is not immediately apparent. A number of interesting reports came from 

 American army camps during the first World War when those who made them 

 were doubtless hard pressed to find the necessary time for this work. These 

 writers are to be warmly commended for their enterprise. 



Chest Conditions Probably Showing PIE and Sequels from Local 



Alveolar Overstrain 



Influenza is an outstanding example of diseases in this class. Torrey and 

 Grosh^ reported patients in the epidemic of 1918-1919 who had dyspnea, 

 cyanosis, fixation of the chest in a position of maximal inspiration, with 



