Perioperative gastric tonometric PCO2 and intramucosal pH in patients undergoing liver transplantation

Extensive research has focused on the role of insufficient gastro-intestinal perfusion and inflammatory activation in the development of organ dysfunction during critical illness. In patients undergoing liver transplantation, portal and caval vein clamping leads to gastro-intestinal and lower extremity venous congestion during the anhepatic phase, and studies suggest that gastro-intestinal perfusion may be compromised. This study was performed to investigate gastro-intestinal perfusion in patients undergoing liver transplantation.

In 16 patients undergoing liver transplantation, perioperative gastric tonometry with determination of tonometric PCO2, tonometric-arterial PCO2 gradient and intramucosal pH were performed. Blood gases were obtained simultaneously from the arterial and portal vein blood.

Tonometric PCO2 was 4.6 (4.2/5.3) kPa preoperatively and increased to 5.6 (4.5/6.0) kPa during the anhepatic phase (P<0.01), while the tonometric-arterial PCO2 gradient increased from -0.3 (-0.5/0.0) kPa preoperatively to 0.7 (0.3/1.2) kPa during the anhepatic phase (P<0.01). Intramucosal pH decreased to 7.27 (7.21/7.32) u during the anhepatic phase (P<0.01, compared to preoperatively). The portal vein PCO2 was not significantly different from arterial PCO2 or tonometric PCO2 at any measurement point.

This study demonstrates that clinical liver transplantation is associated with gastro-intestinal perfusion in the range of aerobic metabolism. The results do not support the presence of gastro-intestinal perfusion in the range of anaerobic metabolism.