Macklin and Macklin 355 



alveolar pressure would be raised during this phase. The action is so rapid 

 tliat there woidd not seem to be time for local inetjualities of distention of 

 alveoli to develop, nor could Factor "B" gain head for the same reason. The 

 effect of the decompression wave, which follows immediately after, would tend 

 to convert the hyperatmospheric intrapulmonic pressure to hypoatmospheric, 

 with distention of the alveoli; but it is impossible to visualize the inert lung 

 substance in its reactions to these almost instantaneous happenings. Most of 

 the reports have featured numerous areas of hemorrhage, not only on the sur- 

 face but also in the depths of the lung, as the salient pathological picture. In 

 some ways this suggests a bruise of the lung. We have found no reports on such 

 lungs which have been specially fixed by injection of the preserving fluid into 

 the bronchial tree and which have been studied both grossly and microscopi- 

 cally in an effort to find the exact points where the hemorrhages occurred. 

 It seems clear, however, that the hemorrhagic points were multiple. There has 

 naturally been considerable discussion as to whether it is the compression or 

 decompression phase which is responsible for this damage, with Ztickerman,™ 

 favoring the former. 



\V^hen reports of lung blast first began to appear in this present war we read 

 the descriptions very carefully to ascertain whether PIE was occurring in the 

 victims who lived for some hours or days after, and our expectations were 

 realized by such reports as those of Dean and his co-workers" and of O'Reilly 

 and Gloyne." We had felt, from our study of the functional anatomy of the 

 lung, that PIE might be predicted in these cases. Although it was not likely 

 that much air would be driven into the interstitial tissues of the lung dining 

 the actual blast waves, yet ruptures would probably then occur through which 

 air would continue to leak into the interstitium and possibly set up an air- 

 block. The accounts which finally confirmed our belief that PIE would occur 

 in some of these lung-blast patients gave the clinical picture as follows, al- 

 though not all of the symptoms might be present in any one case exhibiting 

 any of them: cyanosis of marked degree; extreme dyspnea, the chest being 

 fixed in a position of maximal inspiration; substernal pain; acute abdominal 

 pain for which no explanation could be found at exploratory laparotomy; 

 extreme restlessness requiring opiates; diplopia; and occasional pneumo- 

 thorax. At autopsy, air was found in the mediastinum and pleural cavity, and 

 there was extravasated blood in the carotid sheaths and mediastinum for which 

 no bleeding point could be found, in addition to the numerous areas of hemor- 

 rhage throughout the depths of the lungs. 



We think it reasonable to postulate that PIE and its sequelae account for 

 these findings. The cyanosis, dyspnea, and chest fixation we have already ex- 

 plained as indicative of airblock. The substernal pain might well be caused 

 by the pressure of trapped air on the mediastinal contents, as in Hamman's*' 

 cases. The abdominal pain might justifiably be attributed to extreme ab- 

 dominal distention with tension on the ureters and pressure on the intestines 

 by retroperitoneal air. Cases have been reported in which acute abdominal 



