3^8 Pulmonic Interstitial Emphysema 



Closely analogous are the resuscitation cases, when air or oxygen is forced 

 into the lung under pressure. There is always danger of PIE in such induction 

 of artificial respiration. The pulmotor examples will readily come to mind. 

 Cases such as near-drowning, electric shock, gas asphyxia, and asphyxia neona- 

 torum are so often in extremis that desperate measures may be warranted. The 

 airblock syndrome is not manifest, since breathing is almost, or quite, sus- 

 pended. Factor "B" would be a likely contributor to PIE production in these 

 cases. 



Withdrawal of the air should be done in all of these cases whenever it is 

 deleterious; indeed the idea should be considered by physicians, surgeons, and 

 anesthetists of inserting a hollow needle routinely into the anterior medi- 

 astinum to draw off any air which might happen to have invaded that region 

 during the emergency. In this way we could be fairly sure that the circulatory 

 and respiratory systems would not be incommoded by the treatment. 



Miscellaneous Cases of PIE 



There is a group of cases in which air was found in the mediastinum, pleural 

 cavity, subcutaneous tissues, etc., but in which no cause of PIE is obvious. 

 Signs of aberrant air are found, for instance, after the person awakes from 

 sleep, or following a quiet walk, or while sitting in a car, or during shaving, etc. 

 The relatively quiescent nature of the bodily state at the time of the first 

 symptoms has been stressed. Superficially, it would appear that none of the 

 predisposing circumstances were present. When it is recalled, however, that 

 little appreciation exists of the wide variety of the factors which might pre- 

 cipitate PIE, and that considerable time may elapse between the initial causal 

 event and the accumulation of enough air in the mediastinum to be diagnosed, 

 it will be admitted, we think, that in some of these patients an initiatory event 

 might have been found had the physician known what to inquire for and 

 made an honest effort to find it. 



We have referred to the gravity of atelectasis'" as a predisposing cause in such 

 cases. This is commoner than many physicians think. More frequent and better 

 X-ray examinations in all such cases will, we feel certain, disclose it oftener. 

 Associated infections may well contribute to the likelihood of air rupturing 

 from the compensatorily overinflated regions of lung. An atelectasis, too 

 small to be diagnosed in the usual course, might be large enough to do the 

 damage. We know little or nothing about the relative degree of distention, at 

 any one time, of the various regions of even the normal lung, and it is very diffi- 

 cult to go about finding whether the lung tissue is always uniformly expanded 

 or whether the various parts are always more or less unequally expanded with 

 respect to one another. Many aspects of the related pathology of the lung are 

 no clearer. There is still plenty of opportunity for functional anatomy to aid 

 pathology in the lung. 



Then, too, the history of these individuals in the period prior to the first 

 appearance of evidence of PIE should be searched by the attending physician. 



