Effects of prolonged increased intra-abdominal pressure on gastrointestinal blood flow in pigs

Background: The aim of the study was to investigate the effects of prolonged intra-abdominal pressure on systemic hemodynamics and gastrointestinal blood circulation. Methods: The intra-abdominal pressure in anesthetized pigs was elevated to 20 mmHg (7 animals), 30 mmHg (7 animals), and 40 mmHg (4 animals), respectively. These pressures were maintained for 3 h by intra-abdominal infusion of Ringer's solution. A control group of seven animals had normal intra-abdominal pressure (IAP). Transit time flowmetry and colored microspheres were used to measure blood flow. Results: An IAP of 20 mmHg did not cause significant changes in systemic hemodynamics or tissue blood flow. An IAP of 30 mmHg caused reduced blood flow in the portal vein, gastric mucosa, small bowel mucosa, pancreas, spleen, and liver. Serum lactate increased in animals with an IAP of 30 mmHg, but microscopy did not disclose mucosal damage in the stomach or small bowel. An IAP of 40 mmHg was followed by severe circulatory changes. Conclusions: Prolonged IAP at 20 mmHg did not cause changes in general hemodynamics or gastrointestinal blood flow. Prolonged IAP at 30 mmHg caused reduced portal venous blood flow and reduced tissue flow in various abdominal organs, but no mucosal injury. A prolonged IAP of 40 mmHg represented a dangerous trauma to the animals.