Background and objective Ischaemic colitis can be a serious complication after aortic surgery. The paucity of clinical symptoms makes its diagnosis particularly difficult and often delayed. Automated on-line tonometry is now proposed to monitor intestinal perfusion. This study was designed to assess the use of semi-continuous sigmoid-to-arterial [P(r-a)CO2] PCO2 gap monitoring in aortic surgery to detect colonic ischaemia.

Methods This prospective clinical study was realized at the University Hospital of Lille, France, including eight males scheduled for abdominal aortic aneurysm surgery. Intraoperative and postoperative P(r-a)CO2 values were compared with conventional monitoring and colonic mucosa aspect performed by sigmoidoscopy 48 h after surgery. Haemodynamic variables, O2 delivery (DO2), O2 consumption (VO2), O2 extraction (ERO2), lactate, P(v-a)CO2, P(r-a)CO2 were measured peroperatively and every 4 h during a 48-h postoperative period.

Results Intraoperative P(r-a)CO2 values increased significantly with the highest value (4.36 ± 3.42 kPa) observed during aortic clamping when DO2 was the most altered. P(r-a)CO2 continued to deteriorate after surgery with the maximal values between 8 (4.79 ± 3.85 kPa) and 12 (4.68 ± 3.26 kPa) h after surgery. This peak was associated with a significant ERO2 increase counterbalancing an increase of VO2 whereas DO2 tended to decrease. P(r-a)CO2 values began to decrease only at the end of the study. The highest values of P(r-a)CO2 were registered in patients with the most altered haemodynamic variables, severe ischaemic colitis along with higher hospital lengths of stay.

Conclusion Taken together, these data suggest that regional and automated capnometry may be easily used non-invasively to detect peroperative intestinal ischaemia in aortic surgery.