Skeletal Muscle Oxygen Tension and Metabolism During Hemorrhagic Hypotension, and Subsequent Vasopressor Administration †

Although extensive data on the metabolic response to experimental hemorrhagic shock are available' and although some, though less, data are available on changes in tissue oxygen tension during experimental hemorrhagic shock,'" there are no data relating changes in tissue oxygen tension to changes in tissue metabolism during hemorrhagic shock. The present study was instituted to determine the effect of hemorrhagic shock and vasopressor administration on (1) tissue oxygen tension, (2) changes in oxidation-reduction state, and (3) the relation between these two measurements. It was believed that such data would contribute information on the etiology of the metabolic changes associated with hemorrhagic shock as well as on the desirability of using vasopressors in the presence of hemorrhagic hypotension. Since microfluorometric techniques capable of direct measurement in vivo of changes in the ratio of reduced to oxidized components of the respiratory chain7 were not available in this laboratory, the relationship between lactic acid and pyruvic acid was studied to obtain indirect data. The relationship between lactate and pyruvate was selected because the equilibrium between these two substances (Equation 1) is, in the presence of normal lactate