Histomorphologic and ultrastructural lesions of the pancreas in a porcine model of intra-abdominal hypertension

Intra-abdominal hypertension (IAH) and abdominal compartment syndrome are increasingly observed in patients with severe acute pancreatitis (SAP). The aim of this study was to investigate the effects of IAH on pancreatic histology and ultrastructure in a porcine model. We examined 16 intubated and anesthetized domestic pigs with a mean body weight of 50.6 (SD, 3.8) kg. Using a CO2 pneumoperitoneum, the intra-abdominal pressure was increased to 30 mmHg for an investigation period of 6 or 12 h (each study group n = 6). In the control group, the intra-abdominal pressure remained 3.9 (SD, 5.4) mmHg for 12 h. Additional Ringer's solution was infused to maintain cardiac output at the level of controls. After the observation period, specimens were taken for histological and ultrastructural analysis, and animals were killed. Cardiac output did not change when compared with control. Histologically, mild- to moderate-grade necrosis was observed after 12 h of IAH. In the ultrastructural analysis, leukocyte infiltration and swelling of endothelial cells were found. In the acinar cells of the exocrine pancreas, endoplasmic reticulum was dilated, and necrosis was noticed. Mitochondrial damage manifested as cisternal destruction with formation of large vacuoles. In this porcine model, 6 and 12 h of IAH resulted in light-microscopical and ultrastructural changes comparable to pancreatitis in humans. As SAP is often accompanied by IAH, the finding of the underlying study suggests a vicious cycle in which IAH may worsen pancreatitis. Ultimately, these findings are in favor of a decompression in patients with SAP and IAH.