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Background: The purpose of the study was to examine hemodynamic parameters and intravascular volume in a porcine model in the presence of intra-abdominal hypertension (IAH) lasting for 24 hours., Methods: Twelve pigs (52.5 +/- 4.9 kg) were studied over a period of 24 hours. In six animals, the intra-abdominal pressure was increased to 30 mm Hg via carbon dioxide-pneumoperitoneum. The others served as controls. Using the double-indicator dilution technique, intrathoracic blood volume (ITBV), total circulating blood volume, and cardiac output (CO) were measured. Standard parameters (e.g., central venous pressure [CVP]), were also recorded., Results: In the presence of IAH, ITBV and total circulating blood volume were significantly reduced to 55% and 67% of control values. CO decreased to 27% and CVP increased fourfold., Conclusion: IAH leads to significant intravascular volume depletion that is not reflected by the CVP. Assessment of CO and ITBV in the presence of a critically increased intra-abdominal pressure is therefore recommended.

Objective: Intravesical bladder pressure (IVP) measurement is considered to be the gold standard for the assessment of intra-abdominal pressure (IAP). However, this method is indirect, discontinuous, and potentially infectious and relies on a physiological bladder function. This study evaluated two novel methods for direct, continuous IAP measurement., Design and Setting: Experimental study in an animal research laboratory., Subjects: 18 male domestic pigs., Interventions: CO(2) was insufflated to increase the IAP to 30 mmHg for 18 and 24 h in six animals each. Another six animals served as controls. A piezoresistive (PRM) and an air-capsule (ACM) pressure measurement probe were placed intra-abdominally and of IAP was measured every 1 h (PRM/ACM) or every 2 h (IVP). The mean difference between insufflator readings and IAP values and limits of agreement (mean difference +/-2 SD) were calculated., Measurements and Results: In the presence of applied pressure IVP and PRM remained significantly below insufflator readings while ACM values showed no difference. Mean difference (and limits of agreement) were 4.5 (-2.1 to 11.1 mmHg), 1.6 (-8.0 to 11.2 mmHg), and 0.5 (-4.5 to 5.4 mmHg) for IVP, PRM, and ACM. The mean measurement-to-measurement drift of the ACM values was 9.0+/-10.2 mmHg., Conclusions: In this model agreement of PRM and ACM with insufflator readings was comparable to IVP. As both methods may be advantageous regarding continuous straightforward measurement of IAP, the employment in further experimental and clinical investigations is suggested.

The definitive closure of the abdominal wall, i.e., a closure of the fascial layer and skin may not be favorable in the treatment of numerous surgical conditions, e.g., peritonitis, trauma, or mesenteric ischemia. In these cases, the abdominal wall is temporarily closed, and a laparostomy is created to facilitate re-exploration or to prevent abdominal compartment syndrome. Regarding the technique and material used for the temporary closure, no prospective randomized data exists, but mesh materials are commonly used. They provide drainage of infectious material, permit visual control of the underlying viscera, facilitate access to the abdominal wall, preserve the fascial margin, enable healing by secondary intention, and allow mobilization of the patient. In the case of decreasing intra-abdominal pressure, meshes can be trimmed to centralize the rectus muscle and to facilitate definitive closure. Non-absorbable meshes have been frequently reported to cause enteric fistulae and persistent infection necessitating mesh explantation. While these infectious complications appear to occur less frequently with the use of absorbable materials, these meshes will finally lead to an incisional hernia, requiring repair with non-absorbable mesh after a period of 6-12 months. Nevertheless, in the complex situation requiring a temporary abdominal wall closure, use of absorbable mesh material is common and represents the state of the art.

The purpose of this study was to investigate whether an intra-abdominal pressure (IAP) of 30 mmHg lasting 24 h in a porcine model will lead to a condition comparable with the abdominal compartment syndrome (ACS) in humans. We examined 12 intubated and anesthetized domestic pigs with a mean body weight of 52.5 +/- 4.9 kg. Using a CO2 pneumoperitoneum, the IAP was increased to 30 mmHg (study group, n = 6) for an investigation period of 24 h. In the control group, the IAP remained unchanged. Investigated parameters were cardiac output (CO), peak inspiratory pressure (PIP), urine output (UO), as well as serum alanine aminotransferase (ALT), lactate, lipase, and alkaline phosphatase (AP). Additionally, histopathological examinations were performed. In the study group, CO was significantly reduced compared with the control group. All animals of this group became anuric and their PIP exceeded 40 cm H2O. Furthermore, ALT, AP, lipase, and lactate were significantly increased. Histopathologically, high-grade atelectasis in the lower lobes of the lung together with medium grade liver necrosis, medium grade proximal tubular epithelial necrosis, and medium grade mucosal bowel damage were observed. In this porcine model, an intra-abdominal pressure of 30 mmHg led to a condition comparable with the ACS. Because function or integrity of additional organ systems was impaired, an IAP of 30 mmHg has to be considered a predisposition for the multi-organ dysfunction syndrome in this porcine model.

Background: An intra-abdominal pressure (IAP) of 15 mm Hg reduces intestinal organ perfusion in humans and animals, but it is unknown whether this results in organ damage. The purpose of this study was to evaluate if an IAP of 15 mm Hg lasting for 24 h in a porcine model will lead to morphologic impairment of intestinal and adjacent organs., Methods: We examined 12 intubated and anesthetized domestic pigs (51.8 +/- 4.4 kg). Using CO2 pneumoperitoneum, the IAP was raised to 15 mm Hg (study group, n = 6) for an investigation period of 24 h. In the control group, the IAP remained unchanged. Investigated parameters were cardiac output (CO), peak inspiratory pressure (PIP), and urine output (UO), as well as serum creatinine, alanine aminotransferase (ALT), lactate, lipase, and alkaline phosphatase (AP). Additionally, histopathological examinations were performed.Results. In comparison to the control, CO did not change, while UO decreased significantly by 59% and PIP increased significantly to more than 30 mbar. Serum ALT and AP increased significantly while there was no change in creatinine, lactate, and lipase. Histopathologically, low-grade liver necrosis (12% of liver lobuli), low-grade proximal tubular epithelial necrosis, and low bowel mucosal damage were observed.Conclusion. In this porcine model, an IAP of 15 mm Hg lasting for 24 h was found to result in functional and morphologic impairment of lungs, liver, kidneys, and bowel. These results imply that a prolonged IAP of 15 mm Hg predisposes to multiorgan dysfunction and that a safe duration of increased IAP still has to be determined.