Hepatic splanchnic function in acutely hypoxemic humans at rest

Abstract

Splanchnic metabolism of O2, glucose, and lactate was studied in five normal men during rest while breathing air, 10.4% O2 [arterial O2 partial pressure (PaO2) = 34.8 Torr], and in four men breathing 7.6% O2 (PaO2 = 27.0 Torr). Despite reduction in arterial O2 content to 10.7 ml/100 ml, splanchnic O2 uptake (VO2) and arteriovenous O2 difference remained constant through a fall in hepatic venous O2 content to 7.3 ml/100 ml. Hepatic release of glucose and uptake of lactate were unaffected by either moderate or severe hypoxemia. In five other men hepatic extraction efficiency, removal rate, and clearance of norepinephrine (NE) and epinephrine (E) (radioenzymatic assay) were determined, while air and 10.27% O2 were breathed, and while NE was infused over widely ranging rates (constant in a given subject). Over arterial concentrations of 1.8-17 ng/ml for NE and 0.03-0.3 ng/ml for E, splanchnic removal was closely related to arterial concentration and was unaffected by hypoxemia. NE extraction efficiency rose from 60 (control) to 94% (during infusion in normoxia and hypoxemia); E extraction efficiency remained constant at 85% under all conditions. Hepatic clearances of both NE (556-824 ml/min) and E (630-804 ml/min) were unaffected by hypoxemia. The only observed deficiency in hepatic function was a significant decrease in extraction of indocyanine green in all 10 subjects at both levels of hypoxemia.