Appearance of excess lactate in anesthetized dogs during anemic and hypoxic hypoxia

Abstract

Ten anesthetized, splenectomized dogs were made progressively anemic by replacement of blood with warmed dextran to approximate hematocrits of 30, 20, 15, and 10%. A second group of 10 dogs was made progressively hypoxic by having them inspire 11.4, 9.5, 8.0, and 5.9% O2 in N2. Blood gas contents, pH, and gas tensions were measured in arterial and mixed venous bloods. Cardiac output was calculated from the arteriovenous O2 difference and the O2 uptake. Excess lactate was calculated from measured levels of lactate and pyruvate in blood water. Excess lactate appeared at higher mixed venous Po2 in anemic animals than in hypoxic, 40 mm Hg versus 20 mm Hg. When related to total oxygen transport, however, excess lactate appeared at about the same point (12 ml/kg per min) in both groups. Because liver has been shown to reduce its oxygen uptake with any lowering of perfusate oxygen content, it was suggested that the excess lactate measured during both anemic and hypoxic hypoxia in anesthetized dogs is largely the result of liver dysfunction with respect to lactate.