Macklin and Macklin ^^q 



scarcely any tidal flow of air, and retrosternal pain. When these patients died, 

 as was usually the case, there was not enough involvement of the lung to ex- 

 plain the marked respiratory distress. There were areas of consolidation, with 

 other areas of compensatory hyperinflation.^" The lungs did not collapse as 

 readily or as fully as did normal lungs when the thorax was opened, and there 

 were often numerous blebs, usually unruptured, beneath the pleura.'" Some- 

 times these moribund patients showed sudden improvement, the cyanosis less- 

 ened, the breathing became much easier and of fuller excursion, and the 

 patient usually went on to recovery. The condition which always accompanied, 

 and seemed to explain, this sudden improvement was the appearance of sub- 

 cutaneous emphysema of the neck and face. The implications of this were not 

 realized, and no attempt was made to remove the air from the mediastinum, 

 thus relieving the pressure which was causing the symptoms. It seems to us 

 likely, however, that had such a procedure been followed, many of those dying 

 could have been saved. These various authors reported over 1,100 such patients, 

 thus demonstrating that this condition is not uncommon. 



A very interesting finding was that of "air streaks" along the course of the 

 pulmonary blood vessels in roentgenograms taken of influenza patients.^ This, 

 in our view, is the first X-ray demonstration of perivascular PIE. Air bubbles 

 along the vessels of the hand were reported as having been seen in such pa- 

 tients.^' Again, the importance of these findings was not generally recognized. 

 The simultaneous appearance of pneumothorax and subcutaneous emphysema 

 in some of the patients was interpreted by Berkley and Coffen" as being de- 

 pendent upon a single cause, namely, air in the mediastinum which had 

 reached that region from the pulmonic "air streaks" already mentioned. We 

 feel that these authors should be credited not only with the first X-ray demon- 

 stration of PIE but with the discovery that PIE causes mediastinal emphysema 

 and, through this, subcutaneous emphysema and pneumothorax. This impor- 

 tant research came out of an American army camp during the first World War. 



Apart from epidemic influenza, there are reports of other infectious diseases 

 involving bronchopneumonitis with probable atelectasis which provide evi- 

 dence of some variety that PIE was present. Among such may be mentioned 

 measles,''* pneumonia,'^'' bronchopneumonia*" including the postoperative type, 

 and diphtheria." *" This great group of bronchopneumonic inflammatory con- 

 ditions is most important, and careful watch for symptoms and signs of air- 

 block should be kept so that immediate steps may be taken to relieve it. 



There are also conditions which, though not infectious in themselves, yet 

 nevertheless lead to atelectasis through the mechanical disturbance they oc- 

 casion or through inflammatory reactions they set up in the bronchi; and so, 

 because of the area or areas of compensatory emphysema which ensue, they 

 result in PIE and its sequelae. In this category are the foreign body impac- 

 tions,"" occlusion of a bronchus by tuberculous lymph nodes,"^ or possibly 

 cancer, scarring of the lung tissue by silicosis,'" or tuberculosis.*' Particularly in 

 the cases of atelectasis which occur suddenly is there danger of leakage. 



