44 DISEASES OF THE LUNGS 



to the lower lung. The attending heart weakness undoubt- 

 edly assists. 



Pulmonary Edema. — Definition. — ^A transuding of serum 

 into the alveoli and bronchioli. It is the next step in conges- 

 tion, which it accompanies; it also occurs in pneumonia. 



Etiology. — ^Edema usually follows congestion, the advanced 

 stages of which it represents (serous pneumonia). The causes 

 are, therefore, those of congestion and pneumonia, i. e., 

 inhalation of irritant gases, acute infectious diseases (malig- 

 nant edema, anthrax); may attend severe acute nephritis; 

 any heart weakness; bronchial parasites (Str. paradoxus in 

 swine). 



Symptoms. — ^As pulmonary congestion and edema are 

 always more or less combined, their symptoms may be 

 treated together. They are: Dyspnea which develops 

 rapidly. Sometimes the patient becomes apneic. The 

 respirations may reach 80 to 100. If the edema is well 

 developed, there is a foamy, blood-tinged nasal discharge. 

 The mucous membranes may be cyanotic. The heart 

 beat is often palpitating, the pulse, at first full and rapid, 

 later becomes weak. Percussion is normal. Auscultation: 

 Exaggerated vesicular breathing, crepitant rales, moist rales. 



Course. — May be very rapid, especially if it follow active 

 congestion. In six to twelve hours the symptoms may 

 abate or lead to death. Following passive congestion, the 

 course may be four to six days with lethal termination. 

 Apoplectic death may also occur. Rarely pneumonia 

 develops. 



Diagnosis. — The dyspnea, sudden onset and usually rapid 

 course are characteristic. From acute bronchitis it is 

 distinguished by the absence of fever and distressing cough 

 and the presence of crepitant rales and foamy nasal dis- 

 charge. Heat stroke resembles it but the high temperature 

 (may reach 112° F.) and nervous prostration of this condition 

 are sufficient for differentiation. 



Prognosis. — Usually good in robust patients. A weak 

 pulse and fever are bad signs. Pulmonary congestion and 

 edema are often fatal. 



Digitized by Microsoft® 



