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Physiologic Changes with Abdominal Wall Reconstruction in a Porcine Abdominal Compartment Syndrome Model
Raja Mohan, MD, Helen G. Hui-Chou, MD, Howard Wang, BS, Arthur J. Nam, MD, Michael Magarakis, MD, Gerhard S. Mundinger, MD, Emile N. Brown, MD, Alex Kelamis, MD, Luke Jones, BS, Cinthia B. Drachenberg, MD, Leigh A. Price, MD, Michael Christy, MD, Eduardo D. Rodriguez, MD DDS.
University of Maryland/Shock Trauma Center, Baltimore, MD, USA.
Abdominal compartment syndrome (ACS) is a severe complication of large ventral hernia repairs. The aims of this study were to investigate the effects of intra-abdominal pressure on the physiologic changes of primary ventral hernia repair (VHR) and components separation (CS) in a porcine model.
VHR was simulated by abdominal fascial imbrications of a 10x15cm defect. Forty-five Yorkshire pigs were divided into five groups(Figure 1). Group 1 received VHR alone; group 2 underwent VHR and had ACS; group 3 received VHR and CS; group 4 had VHR, CS, and ACS; group 5 had VHR, CS, and mild ACS. CS was performed by division of external oblique muscles. ACS was modeled by using Stryker® endoscopy insufflator to elevate IAP to 20 mmHg. IAP, bladder pressure (BLP), and femoral central venous pressure (CVP) were measured before and after VHR and CS. Physiologic parameters were monitored for four hours. Animals were desufflated, recovered and euthanized for histologic analysis of organ damage.
VHR was performed in all 45 animals and led to an increase in IAP, BLP, and CVP by an average of 14.89, 13.93, and 14.69 mmHg, respectively (p<0.01). CS was performed in 25 animals and reduced the three pressures by 9.11, 8.00, 7.89 mmHg, respectively (p<0.01, Figure 2). Comparing the animals with ACS (n=30) to those without (n=10) at one hour after the operation, significantly elevated levels of CVP (23.27 vs. 6.64 mmHg, p<0.01), BLP (24.40 vs. 7.36 mmHg, p<0.01), peak inspiratory pressure (PIP) (39.97 vs. 22.09 mmHg, p<0.01), and mean airway pressure (MAP) (15.13 vs. 10.73 mmHg, p<0.01) were observed. The differences persisted through the four hours of monitoring and resolved upon desufflation. No significant differences were seen with heart rate, oxygen saturation, blood pressure, cardiac output, or systemic vascular resistance. The mild ACS group, group 5, also had significantly elevated CVP (10.83 vs. 6.64 mmHg, p<0.05), BLP (14.83 vs. 7.36 mmHg, p<0.05), PIP (28.67 vs. 22.09 mmHg, p<0.05) and MAP (14.00 vs. 10.73 mmHg, p<0.05) compared to animals without ACS at one hour postoperatively. Within the subset of animals with ACS, those that had received CS in addition to VHR did not demonstrate significant differences in the measured physiologic parameters compared to animals with VHR alone; however, the CS group did have a significantly lower percentage of animals with large bowel necrosis (29% vs. 87%).
The results confirm that primary repair of large abdominal wall defects leads to an increase in IAP, which can be reduced with separation of components. In animals with ACS, CS may reduce the risk of organ damage. CVP, BLP, PIP, and MAP accurately correlated with elevated IAP and may be used as surrogate markers for diagnosis of ACS.
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