288 FETAL HEPATIC VENOUS OXYGEN SATURATION AND LIVER OXYGENATION

Abstract

Previously we showed that the left lobe of the fetal liver in fetal lambs receives highly saturated O2 umbilical venous (UV) but no poorly saturated portal venous (PV) blood. Total left lobe flow is 350 ml/min/100g, whilst the right lobe flow is 500ml/min/100g and it receives PV and UV blood. To assess whether the differing blood O2 sats entering the two lobes affect oxygenation, we developed methods for chronic cannulation of the hepatic venous veins (HV) in fetal lambs. The left and right HV join the inferior vena cava (IVC) anteriorly just below the diaphragm; they were cannulated through pursestring sutures in the thoracic IVC through right thoracotomy. In 24 fetal lambs (116-122 d) we placed catheters in L or R HV, PV, IVC, and descending aorta (AO). The O2 sat in the LHV was higher than that in RHV; it was close to UV O2 sat, but RHV O2 sat was similar to that in AO. O2 sats (percent) were: Blood flows to the R and L lobes of the liver from hepatic artery, UV, and PV were measured with radioactive microspheres and, together with O2 content in various vessels, we showed that oxygen consumption in ml/100g/min were similar in left (3.4) and right (3.9) lobes of the liver. The different O2 sats in L and R HV could be important in determining oxygen supply to various fetal organs, depending on distribution of L and R HV blood. (Supported by NIH grants HL 06285 and HL 24056.)