CHEMISTRY OF PNEUMOTHORAX 305 



CHEMISTRY OF PNEUMOTHORAX 



In connection with the subject of exudates the above topic 

 may appropriately be considered. The com position of the gases 

 found in the pleural cavity in pneumothorax will necessarily 

 vary greatly according to the cause. If the pleural cavity is 

 in free communication with the exterior, the gas will be simply 

 slightly modified air ; for example, Ewald l found the following 

 proportions in the gases in such a pneumothorax: CO 2 , 1.76 

 per cent. ; O, 18.93 per cent. ; and 79.31 per cent. N. Here 

 the proportion of CO 2 is even a little less than in ordinary expired 

 air, which contains 3.3-3.5 per cent. When air enters a closed 

 pleural cavity and no effusion follows, it is slowly absorbed. 

 At first there is a rapid absorption of oxygen, which is partly 

 replaced by CO 2 , with a resulting relative increase in nitrogen. 

 Ordinarily the entrance of air into the pleural cavity is followed 

 by an effusion, either serous or purulent, which may modify the 

 composition of the gas. In a seropneumothorax Ewald found 

 8.13 per cent, of CO 2 , 1.26 per cent, of O, and 90.61 percent, 

 of N, which is quite similar to the proportions of the gases in 

 dry pneumothorax. Purulent pneumothorax generally shows 

 more CO 2 than the serous form, the average in the former being 

 15-20 per cent., in the latter 7.5-11.5 per cent. The average 

 of the analyses in six cases of pyopneumothorax is given by 

 Ewald as 18.13 per cent. CO 2 , 2.6 per cent. O, and 79.81 percent. 

 N. In open pyopneumothorax the gas approaches more closely 

 the composition of air, but usually shows a slight excess of CO 2 ; 

 it is thus possible by a determination of the carbon dioxide to 

 determine quite accurately whether a given pneumothorax is 

 in communication with the outside air. The transformation 

 of a purulent into a putrid pneumothorax is accompanied by an 

 increase of CO 2 , even as high as 40 per cent, having been 

 found. The products of decomposition by the putrefactive 

 saprophytes also are present, one analysis having shown 4.3 

 per cent, of hydrogen, 6.25 per cent, of methane, and traces 

 of hydrogen sulphide. 



Infection of a pleural effusion by gas-producing organisms 

 may also convert it into a pneumothorax, although this is not a 

 common occurrence. The gases then present are the same as 

 the organisms produce in similar culture-media, modified some- 

 what by absorption. The anaerobic gas-producing organisms 

 have been found as the cause of such gaseous accumulations ; it 



1 Complete literature and re"sum given by Clemens, in Ott's " Chem. Path, 

 der Tubemilose," Berlin, 1903, p. 406. 



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