[Assessment of oxygen transport in individual splanchnic organs using critical oxygen extraction]

Vulnerability in individual organs under ischemic stress can be assessed by critical oxygen extraction (critical O2ER). We measured critical O2ER in the whole-body, total splanchnic organs, liver and gut using a biphasic regression model of the oxygen delivery-consumption relationship in 7 dogs subjected to hemorrhagic stress under 1% isoflurane anesthesia. The difference in critical O2ER between the whole-body and total splanchnic organs was not significant, while hepatic critical O2ER was significantly larger than that of the gut (P < 0.05), 89.7 +/- 2.4% (mean +/- SD) and 66.1 +/- 5.1%, respectively. This finding indicated that the liver functions well under ischemic conditions due to its excellent ability to extract oxygen. The anatomical character of the sinusoid and the microcirculatory improving effect of isoflurane may affect the ability of oxygen extraction of the liver. The critical threshold of hepatic venous oxygen saturation as a marker of hepatic oxygen imbalance was considered to be below 10%.