Alterations in portal vein blood pH, hepatic functions, and hepatic histology in a porcine carbon dioxide pneumoperitoneum model.

BACKGROUND: Intra-abdominal high pressure and acidosis by carbon dioxide (CO(2)) pneumoperitoneum is known to affect various organ functions. In this study, changes in liver functions and liver histology were investigated during CO(2) pneumoperitoneum in a large animal model.
METHODS: Fourteen white pigs were anesthetized with intubation and controlled ventilation. The pigs in the pneumoperitoneum group (PG) were exposed to CO(2) pneumoperitoneum at an intra-abdominal pressure of 8 mmHg, and those in the open laparotomy group (OG) were subjected to laparotomy. Hemodynamics were measured and liver function tests were performed in the carotid artery and portal vein, and the liver tissue was histologically examined.
RESULTS: The blood pressure, PO(2), PCO(2), and pH in the carotid artery did not significantly differ between the groups. In the PG, blood pressure, PO(2), and PCO(2) in the portal vein were elevated while the pH was low. There were no significant differences in the levels of aminotransferases and lactate between the groups. In the PG, the arterial ketone body ratio (AKBR) was low at 90 min and the ICG retention rate was high at 180 min; these values differed significantly compared to those at 0 min. Histological examination revealed liver congestion in the PG and no significant change in the OG. In the PG, the TUNEL assay revealed positive staining in the area with focal lytic changes.
CONCLUSIONS: CO(2) pneumoperitoneum at an intra-abdominal pressure of 8 mmHg in a porcine model affected liver functions and caused histological changes in the liver. Although it is uncertain whether these alterations observed in the porcine liver occur in humans as well and whether the alterations are reversible after pneumoperitoneum, it may be necessary to pay attention to liver damage during laparoscopic surgery.