SHOCK . 309 



extensive destruction of muscle, or when the liver or intestines are roughly 

 handled. It is possible also that the shock of intestinal obstruction is fun- 

 damentally due to absorption into the blood of similar substances from the 

 closed loop of intestine. Whipple and Hooper's discoveries that absorp- 

 tion of a proteose is responsible for the shock-like symptoms of intestinal 

 obstruction are very suggestive in this connection (page 538). 



The Possibility that Traumatic Toxemia is a Factor in Surgical Shock. 

 Is it possible that surgical shock is dependent upon intoxication by hista- 

 rnine-like substances absorbed from greatly damaged tissues? To test this 

 hypothesis Cannon 38 and others have investigated the effects of crushing 

 the muscles of the hind limbs, without external hemorrhage, by blows 

 from a heavy hammer. It was found that an immediate fall in blood pres- 

 sure occurred, followed by a more gradual decline to the shock level, with 

 a decrease in the C0 2 -combining power and a marked concentration of 

 the blood. This result was not due to irritation of afferent nerves, caus- 

 ing excessive stimulation of the vasomotor centers, since it persisted in 

 animals in which all nerves of the limb had been cut; neither was it caused 

 by any local loss of circulating fluid (by dilatation of vessels or extra- 

 vasation). It was due to the discharge into the circulation of some toxic 

 material, since no shock resulted when the vessels of the damaged limb 

 were clamped. Removal of the clamp some time after the damage re- 

 sulted in the immediate appearance of the symptoms which could again be 

 caused to disappear somewhat by its reapplication. As to the nature 

 of the toxic material, the first possibility to be considered is that it is 

 unoxidized acid (lactic), which, it is well known, accumulates quickly in 

 muscular tissue whenever this is destroyed, or when the circulation 

 through the tissues is greatly curtailed. As a matter of fact it was found 

 that the C0 2 -carrying power of the blood became greatly depressed when- 

 ever the toxic material was permitted to enter the circulation by removal 

 of the clamp, and it is well known that there is also a decided depres- 

 sion in the blood carbonates in surgical shock. Acid intoxication can 

 not, however, be the main factor, and for the following reasons: (1) 

 Injections of lactic acid intravenously do not cause shock, neither do they 

 predispose an animal to it. (2) Copious injections of bicarbonate solu- 

 tion do not prevent shock. (3) Extracts of damaged muscle made with 

 isotonic saline do have a shock-like effect, but this is just as great when 

 the lactic acid in the extracts is neutralized with bicarbonate, as when 

 they are unneutralized. Moreover the fall in the blood carbonate does not 

 coincide with, but rather precedes, the development of the shock symp- 

 toms. An excess of lactic acid in the blood has been noted in the later 

 stages of many cases of shock (Wiggers and Macleod), but this is a sec- 



