OCCLl'SIOX Ol- I.IXI'.R— SMLMW.W axu LKWIS 223 



TAUI.K 11 

 Ocii.rsiox AM) Hki'atk Kkskctiox at NoRMAi, 'rK.\iri:i<ATiui-: 



No. Duration 



of of 



clogs occlusion I^eniarks 



6 40 minutes 4 survivors, 3 with ncuro deficit 



Neither death due to liemorrhage 

 from operative site 



occurred in the immediate postoperative period; neither was (hie to hemorrhage 

 from the raw sin' face of the hver. 



Group III. Tweh'e dogs were sul)iected to hepatic resection and 20 to 40 min- 

 utes of occlusion under hypothermia. Resuhs are seen in tahle II J. Hypothermia 

 of 22° to 28° C. was induced hy ice water immersion, and hot water at 45° C. was 

 used for rewarming. Artificial respiration was maintained throughout l)oth the 

 coohng and rewarming procedures. X'entricular tihrillation did not occur, and there 

 were no deaths either earh' or late. 



Discussion of experimental results. Finding arterial hlood in the i)rocess of 

 performing hepatic resections could be predicted from the first group of experi- 

 ments. The liver became engorged and cyanotic toward the end of the hour. The 

 intestines also participated in the seciuestration of blood from collaterals since dila- 

 tation of the intestinal veins was considerable. In one experiment at the end of 30 

 minutes portal pressure had quadrupled. To a lesser, but still notable, extent the 

 inferior vena cava Ijelow the liver increased in size during the period of occlusion. 



In all experiments heart action became progressively less vigorous, and the heart 

 rate increased. This cardiac response could well have been a result of blood lost 

 through collateral channels into a field from which it could not return due to 

 obstruction of the inferior vena cava. 



The fact that some dogs at normal temperature manifested hind limb weakness 

 and not others is probably attributable to the variation in collateral circulation to 

 that portion of the spinal cord below the site of-aortic occlusion. None of the dogs 

 in the hypothermia group had hind limb signs. 



Whether (jr not hypothermia is necessary to protect the liver during a period of 

 arterial occlusion is an unresolved problem. In experiments designed to establish 

 the mechanism of death from thoracic aortic occlusion, Edwards concluded that 

 hepatic ischemia was not the lethal factor since maintenance of normal arterial 

 supply to the liver did not affect a 60 per cent mortality associated with 90 minutes 

 of aortic occlusion in the dog.^^ The fact remains that obstruction of the portal vein 

 for 30 minutes or longer is lethal for the dog because of hemorrhagic intestinal 



TABLE III 

 Occlusion and Hepatic Resection under Hypothermia 



No. Duration 



of of 



dogs occlusion Remarks 



f 20 minutes-1 1 n . , r • 



n ,- . - 1^ survivors, no neuro dencit 



1- -< 35 minutes-3 . -. _ 0-7° /- u- u ^ ooo /- 



I ,„ . „ Lowest temp. 22 C, highest 28 C. 



40 minutes-8 



