The splanchnic circulation constitutes a major portion of the total capacitance vasculature and may affect venous return and subsequently cardiac output during low output states. This study assessed the effects of rapid (10 microg/kg over 5 min) and slow (10 microg/kg over 60 min) induction of
endotoxin (Escherichia coli)
shock on splanchnic blood volume in 8 farm swine. Blood volume was measured by using Tc99m-labeled erythrocytes and
radionuclide imaging. Baseline arterial pressure (MAP), central venous pressure (CVP), and liver, splenic, mesenteric and total splanchnic volumes were stable during the 30-min baseline. Approximately 30 min after the rapid
endotoxin infusion, splenic volume decreased by 45%, whereas liver volume increased by 40% and MAP decreased by 60% (P < 0.01). The reduction in splenic volume occurred within 10 min of the
endotoxin infusion, whereas liver volume changes occurred after MAP reduction. The slow
endotoxin infusion also reduced splenic volume by approximately 50% (P = 0.05), whereas MAP declined by 30% (P < 0.05). However, the slow
endotoxin infusion lowered liver volume (P < 0.05). Mesenteric volume was unaffected by the fast or slow
endotoxin infusion. Total splanchnic volume was unaffected by the fast infusion but decreased by 37% in the slow infusion group (P < 0.05). In summary, E. coli
endotoxin reduces splenic blood volume and increases liver blood volume after acute
hypotension ensues.
Endotoxin does not increase total splanchnic blood volume and may actually decrease total splanchnic volume in the absence of
circulatory collapse. This
endotoxin shock model is not associated with blood volume pooling in the splanchnic capacitance circulation.