ADVERSE CONSEQUENCES OF INCREASED INTRAABDOMINAL PRESSURE ON BOWEL TISSUE OXYGEN

Objective: Demonstrate the effect that increased intra-abdominal press ure GAP) has on visceral oxygen delivery and bowel tissue oxygenation (TPO2). Methods: Six Duroch swine underwent abdominal insufflation wit h helium to pressures of 15, and 25 mm Hg for 1 hour. Animals were ins trumented with a pulmonary artery flotation catheter to measure cardia c output and calculate systemic oxygen delivery, Fluorescence quenchin g optodes were implanted in the terminal ileum and the subcutaneous ti ssue of an axillary fold to measure bowel and systemic (control) tissu e oxygen levels, respectively,; Results: Bowel tissue oxygen fell from 43 +/- 12 mm Hg at baseline to 31 +/- 12 mm Hg, with 15 mm Hg of abdo minal pressure at 60 minutes. With 25 mm Hg IAP, bowel TPO2 fell from 24 +/- 12 to 12 +/- 8 mm Hg (p < 0.02). No change in axillary TPO2 was observed during either period of increased IAP. Cardiac output (CO), systemic oxygen delivery, and mixed-venous oxygen saturation (Svo(2)) also declined, although blood pressure and oxygen consumption remained constant.Conclusions: Increased IAP produces significant decreases in bowel submucosal TPO2 without similar changes in extra-abdominal (sub cutaneous) TPO2. This decline is dependent on the extent and duration of the elevation in IAP. Readily accessible parameters, such as CO and Svo(2), also decline with increased IAP and may be useful variables t o monitor as relative indicators of bowel hypoperfusion and TPO2.