Local colonic blood pressure degree through aortic reconstruction procedures: a porcine model

Sigmoideal ischemia after aortic grafting is a severe complication with high morbidity and mortality. To investigate the basics of this circulatory problem an animal model was created with sigmoideal ischemia that could be quantified. For this purpose a new pig model was developed with stable general circulatory and ventilatory parameters for several hours, while at the same time controlled sigmoideal ischemia was induced. In five pigs a left retroperitoneal approach to the aorta was performed to isolate the caudal mesenteric artery (CMA). Sigmoideal ischemia was achieved by ligating the collateral circulation and constricting the distal aorta. A flow probe was applied to the CMA. An intravascular saturation probe was introduced in the caudal mesenteric vein (CMV) and a pulse oximeter was applied to the serosal surface of the sigmoid. Every hour, blood gas analyses from the carotic artery, CMA, and CMV were completed. Registrations of all circulatory and ventilatory parameters were performed with the help of a computer. The mean flow in the CMA was 29 mL/min (13-45) and decreased to 5 mL/min (3-7) after aortic constriction. Parameters reflecting the stability of the model, such as the cardiac index (mean 89 mL/min kg-1), the mixed venous oxygen saturation (mean 67%), and the total body oxygen consumption (mean 3.3 mL/min kg-1), did not change with statistical significance during 4 h of partial aortic constriction. The conclusion is that a new model has been developed of quantitative sigmoideal ischemia in the pig that was stable for several hours.