Early onset of regional intestinal ischemia can be detected with carbon dioxide tension measurement inside the peritoneal cavity

Abstract

Methods for detecting regional gastrointestinal ischemia are rare. An early detection of ischemia in the stomach or ileum can be achieved by the continuous intramucosal PCO(2) (PiCO(2)) measurement in the region. However, physiological consideration suggests that the placement of a fiberoptic CO(2) sensor in the peritoneal cavity should yield comparable results. We tested the hypothesis that a continuous PCO(2) measurement in the peritoneal cavity allows the early detection of regional intestinal ischemia. A laparotomy was performed in six pigs (54.7 +/- 3.7 kg) with a tourniquet being placed around respective vessels to allow complete ischemia of a 2. 75-m part of the ileum. A fiberoptic CO(2) sensor (PiCO(2)-ileum) was placed intraluminally in the ileum outside this segment. A second fiberoptic CO(2) sensor to measure intraperitoneal PCO(2) (i. p.-PCO(2)) was placed inside the peritoneal cavity in close vicinity to the ischemic gut segment. Gastric PiCO(2) was determined by using air tonometry. After baseline measurements, ileal ischemia was induced for 180 min followed by a 30-min reperfusion period. Statistics were performed with a Friedman test followed by Wilcoxon Analysis with P: < 0.01 considered significant. With the onset of local ileal ischemia, a sudden increase in i.p.-PCO(2) from 48.9 (45. 0-51.5) mm Hg (mean and 25-75 percentiles) to 94.3 (87.9-95.5; P: < 0.01) mm Hg was observed. Gastric PiCO(2) (49.0 [47.5-51.0]/53.5 [49. 0-54.0] mm Hg), and ileal PiCO(2) (56.4 [44.6-57.0]/54.3 [46.1-57.8] mm Hg) did not change. With reperfusion, the i.p.-PCO(2) decreased but stayed above baseline values.

Implications: Unless systemic changes are induced, regional intestinal perfusion deficits cannot be detected with a PCO(2) measurement in the gastric lumen. In pigs, an occlusion of blood flow to an isolated gut segment resulted in a significant increase in intraperitoneal CO(2) tension. Thus, the measurement of intraperitoneal PCO(2) could allow the early detection of regional intestinal ischemia.