Hepatic and splanchnic oxygen consumption during acute hypoxemic hypoxia in anesthetized pigs

Objective: To compare the hepatosplanchnic oxygen consumption ((V) over dotO(2)) with the hepatic and splanchnic ire, and to calculate the critical oxygen delivery ((D) over dotO(2)crit) below which (V) over dotO(2) decreases in the hepatic, splanchnic, and hepatosplanchnic regions in a model of hypoxemic hypoxia. Design: Prospective animal study. Setting: University research laboratory. Subjects: Anesthetized and ventilated pigs (n = 7). Interventions: The right carotid artery was cannulated to measure mean arterial pressure. A pulmonary artery catheter was inserted to measure mean pulmonary arterial pressure and cardiac output. After a midline abdominal incision, two flow probes were positioned around the portal vein and the hepatic artery to measure portal vein blood flow and hepatic artery blood flow. Oxygen and lactate contents in the carotid artery, the portal vein, and the hepatic vein were measured in blood samples obtained from the appropriate catheters. Measurements and Main Results: After a 2-hr stabilization period, hemodynamic and biological variables were recorded during acute hypoxemic hypoxia (FIO2 = 0.5, 0.4, 0.3, 0.21, 0.15, 0.10, and 0.07). (V) over dotO(2), (D) over dotO(2), and (D) over dot(2)crit were determined in the hepatic, splanchnic, and hepatosplanchnic regions. The hepatosplanchnic (V) over dotO(2) was 48 +/- 5 mL/min at high FIO2 (40% for the liver and 60% for the splanchnic organs) and decreased below FIO2 of 0.15. Lactate uptake in the whole hepatosplanchnic region remained steady at FIO2 values of 0.5 to 0.15 and then switched to a lactate release at low FIO2. However, the splanchnic region released lactate, whereas lactate was taken up by the liver. (D) over dot(2)crit in the hepatic, splanchnic, and hepatosplanchnic regions was 24 +/- 3, 38 +/- 2, and 49 +/- 4 mL/min, but the systemic (D) over dot(2)crit, below which regional (V) over dotO(2) became oxygen supply dependent, did not differ in the liver, splanchnic, and hepatosplanchnic regions. Conclusions: The variables of oxygenation and lactate flux measured in the hepatosplanchnic region summarize the metabolic changes of various organs that may vary in different ways during hypoxemic hypoxia.