THE BEHAVIOR OF THE SPLEEN IN HEMORRHAGIC HYPOTENSION AND SHOCK

Abstract

Changes in areas of exteriorized spleens were studied in dogs by the method of Barcroft and Stephens during hemorrhage, posthemorrhagic hypotension and hemorrhagic shock. In confirmation of previous reports, it was found that the spleen contracts rapidly and extremely during hemorrhage, the area being reduced by as much as 50% or more. During a period of prolonged posthemorrhagic hypotension the dog''s spleen undergoes a further slow contraction, does not increase on reinfusion of the withdrawn blood, but remains contracted whenever the duration and intensity of the hypotension are sufficient to create dynamic and pathological signs of shock. Similar changes occurred in plasmapheresis expts. In the dog, splenic contraction does not contribute to elevation or maintenance of arterial pressure by virtue of the increased resistance induced in the splenic shunt, but by augmenting venous return and cardiac output. The spleen is not an organ which withdraws blood from active circulation in hemorrhagic shock. When the spleen is found large and congested at autopsy other factors must have operated.