Hepatic Factor in Anaphylactic Shock 



185 



ored to test this theory by studying the effects on carotid blood 

 pressure of a mechanical obstruction to hepatic outflow suffi- 

 cient to produce a combined hepatic and intestinal passive con- 

 gestion equal to the passive congestion observed during anaphy- 

 lactic shock. We have taken the increase in portal blood pres- 

 sure as the measure of this passive congestion. 



The normal portal blood pressure averages about 9 mm.Hg. 

 in our series of dogs. This pressure is increased to about 18 

 mm.Hg. during anaphylactic shock, the maximum being reachetl 

 by the end of one minute. The portal blood pressure then grad- 

 ually falls, and is restored to normal in from 8 minutes to 15 

 minutes. 



To prepare animals for the mechanical test, the inferior vena 

 cava was ligated immediately below the liver in a series of dogs. 

 Examination of these dogs six weeks later, at the time of the 

 tests showed an hypertrophied collateral circulation fully com- 

 pensating for the vena caval ligation. 



To make the tests, an unclosed ligature was placed about the 

 vena cava immediately below the diaphragm. By partially clos- 

 ing this ligature, any desired degree of hepatic-intestinal passive 

 congestion could be produced without interfering with the re- 

 turn circulation from the hind quarters. It was found that care- 

 fully controlled increased resistance to hepatic outflow, sufficient 

 to raise the portal blood pressure to 20 mm.Hg., which is greater 

 than the maximum portal pressure during anaphylactic shock, 

 was without marked effect on the carotid blood pressure. The 

 carotid pressure usually falls slightly on tightening the ligature, 

 but is restored practically to normal by the end of two minutes. 

 It is only when the vena caval ligature is completely closed so 

 as to produce combined hepatic and intestinal stasis, that a fall 

 in carotid pressure is produced at all comparable with the fall 

 during anaphylactic shock. 



We conclude from these tests, that hepatic-intestinal passive 

 congestion, though conceivably a factor of some importance in 

 canine anaphylactic shock, is not the essential or dominant factor 

 in this shock. This finding strengthens our initial theory 2 , that 

 the anaphylactic reaction in dogs is essentially an explosive he- 

 patic autointoxication, the formation or liberation of hepatic 

 products having a histamine-like reaction on the extra-hepatic 

 blood vessels. 



2Manwaring, W. H., Zeitschr. f. Immunitdtsf., 1910, viii, 1; J. A. M. A. 

 1921, lxxii, 849. 



