Differential alterations in systemic and regional oxygen delivery and consumption during the early and late stages of sepsis

Background: Studies have indicated that regional changes in oxygen utilization during sepsis cannot be predicted from the changes in the whole body oxygen delivery (DO2) and consumption (VO2), The aim of this study, therefore, was to determine whether differential alterations in systemic and regional DO2 and VO2 occur during the early and late stages of sepsis, Methods: Adult male Sprague-Dawley rats were subjected to sepsis by cecal ligation and puncture (CLP), At 5 hours (i.e., the early, hyperdynamic phase of sepsis) or 20 hours (i.e., the late, hypodynamic phase) after CLP, cardiac output, and organ blood flow were measured by radioactive microspheres. Systemic and regional DO2 and VO2 were determined and plasma levels of lactate were measured. Results: Cardiac output and blood flow to the liver, small intestine, and kidneys increased at 5 hours and decreased at 20 hours after CLP, Although both systemic DO2 and VO2 increased at 5 hours after CLP, systemic DO2 but not VO2 decreased at 20 hours. At 5 hours after CLP, intestinal and renal DO2 increased. However, DO2 in all the tested organs decreased at 20 hours after CLP, VO2 increased in the liver, small intestine, and kidneys at 5 hours after CLP but decreased only in the liver and small intestine at 20 hours after the onset of sepsis, Moreover, plasma lactate levels increased at the late stage of sepsis, Conclusion: Because hepatic and intestinal VO2 but not systemic and renal VO2 decreased at 20 hours after CLP, the liver and small intestine seem to be more vulnerable to the hypoxic insult during the hypodynamic stage of polymicrobial sepsis.