FUNCTIONAL DETERIORATION OF THE LIVER BY ELEVATED INFERIOR VENA-CAVA PRESSURE - A PROPOSED UPPER SAFETY LIMIT OF PRESSURE FOR MAINTAINING LIVER VIABILITY IN DOGS

Objective. Abnormally elevated central venous pressure is considered t o be an etiological factor in the onset of acute hepatic failure follo wing modified Fontan operation. This paper hypothesises that an increa se in inferior vena cava pressure (IVCP) after such an operation has a dverse effects on hepatic energy status. Design: Various degrees of ve nous hypertension were produced in 10 mongrel dogs by clamping the tho racic IVC with an active veno-venous shunt and varying its flow rate f rom 60-2.5 ml/min/kg. Arterial ketone body ratio (KBR), reflecting the hepatic mitochondrial redox state, was measured as an index of hepati c energy status. Measurements and results: The lower the flow rates of the shunt, the higher the pressures of IVC and portal vein, while sys tolic blood pressure was maintained above 100 mmHg. CO significantly d ecreased when the pump speed was less than 30 ml/min/kg. KBR showed a negative correlation to IVCP as well as a positive correlation to port al blood flow (p<0.05). Conclusion: From the simple regression line ob tained between IVCP and KBR, it was determined that an upper safety li mit of IVCP may lie at about 27 cmH2O (20.5 mmHg), and that a IVCP of 35 cmH2O (26.6 mmHg) seems to be the critical level for maintaining li ver viability.