HYPEILEMIA OF THE LUNG. 



141 



Percussion, finally, which undergoes no change from hyperaemia 

 ilone, sometimes indicates that oedema has supervened upon hyperaemia. 

 The sound upon percussion when the alveolar walls have lost their elas- 

 ticity through oedema, and are but lightly stretched over their contents, 

 is sometimes distinctly tympanitic. If, however, all the air have been 

 driven out of the air-cells by the oedema, and the lung have become 

 void of air, the sound upon percussion becomes dull and flat, as with 

 every other condensation of the lung. If these manifestations appear 

 in the characteristic places for hypostasis, we have to do with this form, 

 or with its sequelae. 



With regard, finally, to that form of cedema of the lung which 

 arises in general dropsy, the appearance of dropsical swelling of the 

 subcutaneous cellular tissue and of effusions in the serous cavities fur- 

 nishes the best grounds for interpretation of the dyspnoea which accom- 

 panies these symptoms. Should serous sputa, moist rattles, a tympanitic 

 or dull sound, upon percussion, supervene, we are warranted in regard- 

 ing pulmonary cedema as their cause. 



DIAGNOSIS. Hyperaemia and cedema of the lung, if we keep in 

 view the symptoms just described, are easily distinguished from other 

 diseases of the lung. It may, however, be very difficult (easy as the 

 matter may appear in the study) to make a distinction at the bedside 

 between active and passive hyperaemia, between fluxion and obstruc- 

 tion ; and, moreover, confusion of the two may lead to the worst conse- 

 quences, to mistakes which not unfrequently threaten the life of the 

 patient. The confusion occurs most frequently between the collateral 

 fluxion, occurring in the course of a pneumonia and pleurisy, and the 

 passive hyperaemia, to which enfeebled heart-action and asthenic fever 

 give rise. We so frequently notice the occurrence of passive pulmonary 

 hyperaemia and cedema of the lung, upon the final exhaustion of the 

 patient, upon the diminution of the pulse, upon the delirium, and the 

 dry tongue, that we are apt also, in cases of recent pneumonia, if the 

 pulse be small, and the patient delirious, to think of passive hyperaemia 

 and of obstruction from commencing paralysis of the heart, and instead 

 of venesection to prescribe wine, camphor, and musk. 



In treating of croupous pneumonia we shall go more fully into detail 

 upon the subject of pulmonary fluxion and engorgement, symptoms of 

 the utmost importance in that disease, and demanding especial considera- 

 tion in its treatment. 



PROGNOSIS. The prognosis of hyperaemia and of cedema of the 



jontain any air, but where, at the same time, the bronchi, which lead to the con- 

 iensed spot, are not filled up by the secretion. It is easy to see that the latter con- 

 dition, requisite for bronchial respiration (of the origin of which we shall speak moie 

 f ully while treating of pneumonia), is almost always wanting in pulmonary oedema. 



