JOURNAL OF SURGICAL RESEARCH 51,425-433 (1991) Low Oxygen Delivery Produced by Anemia, Hypoxia, and Low Cardiac Output

In pentobarbital-anesthetized dogs, oxygen delivery (DO,) was measured by thermodilution cardiac output and cooximeter determined oxygen content, while oxy-gen consumption (VO,) was measured independently by spirometry. Oxygen delivery was decreased by isovole-mic dilutional anemia, breathing hypoxic gas mixtures, or cardiac tamponade to reduce cardiac output. Base-line VO, (cc/hg/min) for the three groups was 5.9 f 0.7 (anemia), 5.4 + 0.4 (hypoxia), and 5.6 f 0.1 (low C.O.) (NS). A critical level of oxygen delivery (DO, & was found at 9-10 cc/kg/min (anemia), lo-11 cc/kg/min (hypoxia), and 9-10 cc/hg/min (low C.O.) (NS.). Below this level, VO, fell (became supply dependent) and lac-tic acidosis occurred, regardless of the mechanism of impaired oxygen delivery. 0 1991 Academic Press, Inc