A total of 205 studies of hemodynamics and blood gas analyses were performed in relation to hepatic mitochondrial redox state in 23 partially hepatectomized patients. When the blood ketone body ratio (the ratio of acetoacetate to β-hydroxybutyrate in arterial blood) decreased, that is when the hepatic mitochondrial redox state was reduced, a hyperdynamic state with increased cardiac index, decreased systemic and pulmonary vascular resistance together with decreased oxygen consumption was observed in spite of the increased oxygen availability. Inhibited oxidative metabolism in the Krebs cycle may have resulted in the decreased oxygen consumption and decreased vascular tone. This study supports the concept that the hepatic metabolic derangements due to reduced hepatic mitochondrial redox state may be a factor in the decreased oxygen consumption and hyperdynamic state