RESPIRATORY APPARATUS. 105 



ing. The back is elevated at expiration and sinks during 

 inspiration. At the moment of expiration the anus is greatly 

 protruded. When the abdomen is well filled, these symp- 

 toms appear more prominently. 

 Expiratory dyspnea occurs : 



1. In vesicular and interstitial emphysema. 



2. In chronic bronchitis and peri-bronchitis. 



3. Where the lung has adhered to the costal wall. 



A mixed dyspnea is present when accelerated 

 respiratory frequency is combined with difficult inspiration 

 and expiration (inspiratory and expiratory dyspnea). It is 

 the most common form of dyspnea and attends all severe 

 diseases of the respiratory tract (pneumothorax, hydrothorax) 

 and also those diseases which have no primary seat but whose 

 course is accompanied by a severe intoxication of the blood 

 with CO, — as in many of the infectious diseases. 



In pronounced mixed dyspnea there is a marked flap- 

 ping of the nostrils. At the beginning of inspiration both 

 wings (medial and lateral) are greatly distended. At the 

 end of the inspiratory movement they again collapse. How- 

 ever, the forced out-flow of air at expiration, which imme- 

 diately follows, forces the medial wing, which is in its path, 

 outward and upward causing a second movement of this 

 wing to occur. 



According to the seat of the respiratory obstruction one 

 speaks of a nasal, laryngeal, trachea! and pulmonary dysp- 

 nea. 



II. The Breath. 



An examination of the exhaled air is of diagnostic im- 

 portance in many morbid conditions. Normally the air is 

 emitted from the nostrils in two odorless currents of equal 

 size. The two deviations from the normal are : e : 



1. The air currents from both nostrils are not of equal 

 size. Where one of the currents is smaller (of less volume) 

 than the other, it points to a narrowing of the nasal 



