360 LUNGS AND PLEURAE. 



bronchial channels. The distribution being no longer regulated by reflex 

 action, air accumulates at certain points as a result of the expiratory 

 efforts made during coughing, and dilatation of the vesicles or lobules 

 occurs. 



Diseases of the digestive apparatus, acute or chronic tympanites in 

 particular, may plaj^ a certain part by compressing the diai^hragm, 

 causing expiratory efforts and fits of coughing. 



Furthermore, swelling of the lymphatic glands at the entrance to 

 the chest, by compressing the pneumo-gastrics, provokes reflex cough 

 and finally emphysema. 



Symptoms. Pulmonary emphysema is marked by accelerated re- 

 spiration due to diminution in the respiratory cajiacity, which is often 

 very seriously afi:'ected ; to insufficient absorption of oxj^gen in con- 

 sequence of diminution in the space available for exchange of gases in 

 the lung, and to insufficiency of expiration. This acceleration in breath- 

 ing, though little marked during repose, becomes very pronounced after 

 exercise, or during hot weather ; and under these circumstances is 

 accompanied by a paroxysmal, feeble but shrill cough, without discharge. 

 This cough without discharge is frequently followed by swallowing. 



Percussion reveals an important point, viz., increase in the normal 

 resonance of the thorax. 



On auscultation the vesicular murmur is found to be diminished, the 

 respiration assumes a rough and rasping character, inspiration is diffi- 

 cult, expiration painful, and often divided into two periods, as indicated 

 by a slight double movement of the flank. Expiration is clearly audible. 

 Its duration is generally less than that of insjDiration, although in some 

 cases it is equal or even longer. It is accompanied by sibilant and 

 snoring rdlcs, sometimes even mucous rales, of an intermittent character. 

 In rare cases there may be difficulty of respiration, as in broken-winded 

 horses. 



Diagnosis. The diagnosis may suggest a doubt as to whether 

 emphysema or tuberculosis is present, but in the latter there is fever, 

 the general condition is poor ; on percussion the thorax reveals areas 

 of partial dulness ; and expiration is rough and prolonged, sometimes of 

 a blowing character, a peculiarity which is exceptional in emphj^sema. 



Prognosis. The prognosis is not very grave, except where emphy- 

 sema is only an accompanying symptom of another disease, such as 

 chronic bronchitis, tuberculosis, etc. 



Treatment. Little can be done to check the development of the 

 above descriljed pulmonary lesions ; but the cough may be relieved, and 

 the pulmonary circulation improved by assisting the heart. 



The most prompt and efficacious assistance is given by digitalis in 

 doses of ^ to 1 drachm per day for adults, iodide of potassium in doses of 



