Continuous intraoperative monitoring of hepatic blood perfusion using a noninvasive surface electrode

Continuous noninvasive measurement of local blood flow at one or more chosen sites will be useful during experiments on the liver, during liver surgery, or after hepatic transplantation. We have compared a Clark-type flow-dependent oxygen electrode having a 3-mm-diameter cathode applied to the surface of rabbit liver to an electromagnetic flowmeter (EMF) on the portal vein. Reduction in portal flow (ranging from 4 to 100% and maintained over 2 min), correlated with reduction in electrode output (r = 0.944, P less than 0.001). Electrode output was independent of systemic arterial PO2 (ranging from 85 to 340 mm Hg) (P greater than 0.99) and thus of oxygen in inspired gases. These results indicate that this electrode gives a continuous indication of portal venous inflow when hepatic central inflow is undisturbed and may thus prove to be a useful tool in the clinical assessment of liver perfusion.