Ketone body ratios of the superior and inferior vena cava and of pulmonary arterial blood compared to that of arterial blood: Central venous ketone body ratio as a substitute for the arterial ketone body ratio

To investigate the ketone body ratio (acetoacetate/3-hydroxybutyrate) of central venous blood compared to that of peripheral arterial blood, the acetoacetate and 3-hydroxybutyrate concentrations in paired peripheral arterial and central venous or pulmonary arterial blood were measured. The ketone body concentrations in superior and inferior vena cava blood were significantly (P < 0.0001) lower than those in peripheral arterial blood, whereas those in pulmonary arterial blood were almost the same as those in peripheral arterial blood, These results indicate that ketone bodies were metabolized in the muscles, which reduced their levels in vena cava blood, but ketone bodies newly produced by the liver were transported to the right side of the heart via the hepatic vein, giving concentrations in pulmonary arterial blood that were almost the same as those in peripheral arterial blood, On the other hand, the correlation coefficients (r(2)) Of the arterial blood ketone body ratio to the ratio of superior and inferior vena cava and pulmonary arterial blood were 0.897, 0.767 and 0.882, respectively. The ratios of central venous ketone body ratio/arterial blood ketone body ratio were 0.89 +/- 0.15 in the superior vena cava, 0.64 +/- 0.18 in the inferior vena cava and 1.01 +/- 0.15 in the pulmonary artery.