Is the deterioration of liver viability due to hepatic warm ischemia or reinflow of pooled-portal blood in intermittent portal triad cross-clamping?

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Abstract
The effects of hepatic warm ischemia and portal pooling on the viability of the liver were investigated with respect to hepatic energy metabolism by performing intermittent portal triad cross-clamping (Pringle's maneuver) on dogs with or without portosystemic shunt. The dogs were divided into two groups of five: Group 1, non-shunt group, underwent Pringle's maneuver performed for 30 min and declamping for 30 min, a process that was repeated five times; and Group 2, shunt group, underwent the same procedure as Group 1, except for portosystemic shunt using a heparinized hydrophilic catheter between the splenic and jugular veins. The shunt was opened during Pringle's maneuver and was closed immediately at declamping. In the non-shunt group, portal pooling increased and systemic blood pressure decreased when Pringle's maneuver was performed, but in the shunt group portal and systemic blood pressures remained within the normal range. In the non-shunt group, the initial velocity of arterial blood ketone body ratio (KBR) recovery after each declamping significantly (P < 0.01) decreased from 0.122 ± 0.016 (per min) after the first declamping to 0.028 ± 0.017 (per min) after the fifth declamping. Hepatic energy charge [= (ATP + 1/2 ADP)/(ATP + ADP + AMP)] decreased from 0.840 ± 0.003 before ischemia to 0.749 ± 0.003 30 min after the fifth declamping (P < 0.001). The concentrations of lactate and total amino acids in arterial blood increased. On the other hand, in the shunt group, the initial velocity of KBR recovery and hepatic energy charge showed little change even after the fifth declamping (0.081 ± 0.016 per min and 0.851 ± 0.009, respectively). The concentrations of lactate and total amino acids showed almost no increase. The impairment of hepatic energy metabolism by intermittent portal triad cross-clamping is mainly due to reinflow of pooled-portal blood to the previously ischemic liver, rather than hepatic warm ischemia. The KBR may be useful for determining the degree of impairment of hepatic energy metabolism.