326 DISTURBANCES OF CIRCULATION 



walls, and probably some fat also escapes through stomata or similar 

 intercellular openings. Fat may also escape in the bile, and some is 

 probably taken up by the tissue and endothelial cells by phagocytosis. 

 Beneke found that the fat becomes partly emulsified by the mechanical 

 action of the blood current, aided to a slight extent by saponification. 

 The larger droplets after lodging -in the capillaries are surrounded 

 by leucocytes, to which Beneke ascribes an active part in the removal 

 of the fat as fine droplets by phagocytic action. We may well believe, 

 however, that the lipase of the plasma is an important agent in disin- 

 tegrating the emboli, although its action is limited because of the rel- 

 atively small surface which the large drops offer for attack. After 

 fat droplets have been taken into the cells, they presumably are util- 

 ized in metabolism like normally acquired fat, as described previously. 



The amount of fat free in the blood in fat embolism may be sur- 

 prisingly large. BisselP* found from 2 to 6.5 per cent, in the venous 

 blood of several typical cases, although sometimes figures within 

 normal limits (0.2 to 0.6 per cent.) were found. The higher quantities 

 represent such a great amount of free fat in the blood, even without 

 considering the quantity held in the capillaries, that it is scarcely 

 possible for it all to have come from the fractured bones. 



Air embolism presents some features of interest from the chemi- 

 cal standpoint, especially in those cases following sudden decrease in at- 

 mospheric pressure in persons who have been exposed for some time to 

 pressures considerably higher than that of the 'atmosphere (diver's 

 palsy, caisson disease, etc.). This form of air embolism is due to the 

 fact that fluids can dissolve much more gas at high pressures than at 

 low pressures; consequently when the abnormall}^ great pressure to 

 which divers, caisson workers, etc., are subjected is too suddenly re- 

 duced to that of the atmosphere, the excessive gas that was absorbed 

 during the period of high pressure by the blood and tissue fluids is 

 released, and forms bubbles in the tissues and blood. The bubbles in 

 the nervous tissues may cause paralyses of various sorts, or death; 

 those in the blood may, if in suffi.cient amount, cause serious or fatal 

 capillary obstruction. The bubbles consist chiefly of nitrogen, bo- 

 cause the power of the blood to hold oxygen in combination is so great 

 that not much of this gas becomes freed. ^^ The body fluids of normal 

 persons contain about 675 c.c. of nitrogen, all told, but at 22 pounds 

 pressure this is increased to 1350 c.c, while but about 50 c.c. of free 

 oxygen would be present (Langlois). Carbon dioxitlc is so readily 

 combined in the blood that none is free even at high pressure, al- 

 though McWhorter-" reports that the gas collected from t he right side 

 of the heart in a fatal case contained 20 per cent. COo antl 80 per cent. 



18 Jour. Aincr. Med. Assoc, lOKi (G7), 1926. 



"• Tliis subject is fully discusscni by Leonard Hill in "Recent Advances in 

 Physiolof^y and Biocheniistry;" London, lOOti. 



2« Anicr. .lour. Mod. Sfi.,"l<)10 (LJ'.)), 'M'.i; Krdinan, //>((/., lOL} (lb")), fyiO. 



