Oxygen transport-dependent splanchnic metabolism in the sepsis syndrome

Abstract

Objective: Total body oxygen consumption (VO2) may be pathologically oxygen delivery (DO2)-dependent in critically ill patients exhibiting the sepsis syndrome. This observation has been used to infer the presence of occult tissue or organ ischemia that potentially can be eradicated by augmenting DO2. We examined this hypothesis by determining the VO2-DO2 relationship and lactate metabolism in the splanchnic region.

Design: Before and after intervention trial.

Setting: University-affiliated Veterans Affairs Medical Center, Allen Park, Mich.

Patients: Eighteen surgical patients exhibiting the sepsis syndrome.

Intervention: Systemic and splanchnic oxygen exchange and lactate uptake measurements before and after augmentation of DO2 with blood transfusion.

Main outcome measures: Changes in oxygen exchange and lactate metabolism.

Results: The splanchnic VO2 index rose 9% in association with a 26% regional DO2 index increase indicating an oxygen transport dependency (P < .05). Splanchnic O2 extraction (0.47 +/- 0.04) was significantly greater than the mean systemic level (0.31 +/- 0.02) and showed a greater decline following DO2 index augmentation (0.41 +/- 0.04 vs 0.28 +/- 0.03, respectively). However, splanchnic lactate uptake was not changed significantly in response to the increased DO2 index.

Conclusions: Although splanchnic oxygen transport dependency and elevated extraction ratios suggest the presence of regional ischemia that should be relieved with an increased DO2 index, the observed changes in lactate uptake do not support this conclusion. The significance of the VO2-DO2 relationship, its role in the pathophysiology of the sepsis syndrome, and its place in the clinical care of the septic surgical patient are in doubt.