A Comparison Among Portal Lactate, Intramucosal Sigmoid pH, and ΔCO2 (Paco2 − Regional Pco2) as Indices of Complications in Patients Undergoing Abdominal Aortic Aneurysm Surgery

Abstract

Our aim in this observational, prospective, noncontrolled study was to detect, in 29 patients who underwent abdominal aortic aneurysm (AAA) surgery, correlations between the incidence of postoperative organ failure and intraoperative changes in arterial and portal blood lactate; changes in intramucosal sigmoid pH (pHi); differences between sigmoid Pco(2) and arterial Pco(2) (DeltaCO(2)); and hemoglobin (Hb). Hb, arterial blood lactate concentrations, pHi, and DeltaCO(2) (air tonometry) were recorded at the start of anesthesia (T0), before aorta clamping (T1), 30 minutes after clamping (T2), and at the end of surgery (T3). Portal venous lactate concentrations were recorded at T1 and T2. Patients were stratified into two groups: group A patients had no postoperative organ failure, and group B patients had one or more organ failures. As compared with group A (n = 16), group B patients (n = 13) had a lower pHi value at T2 and T3 and a higher DeltaCO(2) at T3. A pHi value of <7.15 was a predictor of organ failure, with a sensitivity of 92.3%, a specificity of 68.8%, and positive and negative predictive values of 70.6% and 91.7%, respectively, whereas a DeltaCO(2) value of >28 mm Hg predicted later organ failure with a sensitivity of 92.3%, a specificity of 62.5%, and positive and negative predictive values of 66.6% and 90.9%, respectively. Portal venous lactate concentrations were larger in group B at T2 (P < 0.001), and an increase >or=5 g/dL predicted later postoperative organ failure with a sensitivity of 92.3%, a specificity of 100%, and positive and negative predictive values of 100% and 94.1%, respectively. The comparison of the receiving operator characteristic curves to test the discrimination of each variable and the logistic regression analysis revealed that the increase in portal lactate was the best predictor for the development of postoperative organ failure. Hb concentration was significantly smaller in group B at T0 (13.8 +/- 1.0 g/dL versus 12.2 +/- 2.2 g/dL) and T2 (10.9 +/- 1.2 g/dL versus 9.1 +/- 1.9 g/dL). In conclusion, both pHi and DeltaCO(2) are reasonably sensitive prognostic indices of organ failures after AAA surgery, but they are less specific and accurate than portal venous lactate.

Randomized clinical trial to evaluate the effects of perioperative supplemental oxygen administration on the colorectal anastomosis

“…Björck et al 34 specified a sigmoid pHi of less than 7·1 as an early warning of ischaemic colitis after abdominal aortic surgery. A range of 6·86 to 7·30 has been reported in the literature 13,17 . Few reports, however, have noted cut-off points and accuracy for catheters placed within the colon.…”

“…Bjork et al 34 reported a sensitivity and specificity of 100 per cent for predicting ischaemic colitis when a sigmoid pHi below 6·86 for longer than 4 h was registered. In addition, a sensitivity of 100 per cent, specificity of 92 per cent, positive predictive value of 80 per cent and negative predictive value of 92 per cent was found for predicting major complications when a sigmoid pHi below 7·1 was maintained for 2 h. Donati et al 13 found that a sigmoid pHi value of < 7·15 was a predictor of organ failure with a sensitivity of 92·3 per cent, a specificity of 68·8 per cent and positive and predictive values of 70·6 and 91·7 per cent, respectively.…”

“…However, this is not necessarily true in poorly perfused tissue 10 , so the mucosal-arterial carbon dioxide difference or gap is now used as a more specific marker of gastrointestinal perfusion 11 . Gastric tonometry has gained wide acceptance among intensive care personnel for use as a predictor of risk of complications 12,13 , to guide therapy 14 , and to predict the development of ischaemic sigmoiditis after aortic surgery 15 . A transanal tonometer has been used to predict local septic complications and development of pouchitis in patients undergoing construction of an ileal pouch-anal reservoir 16 .…”

Rectal lactate levels in endoluminal microdialysate during routine coronary surgery*

“…How therefore can, the elevated levels of gut luminal lactate be of clinical relevance? Lactate in the gut lumen is a marker of altered intestinal permeability [16], and in abdominal aortic surgery, elevated levels of lactate in the splanchnic circulation predict organ failure [13]. Our patients were chosen due to the known occurrence of altered permeability during CPB [1], and therefore we expected to detect increased levels of lactate in the gut lumen.…”

“…As tonometry has also been used for monitoring the colonic mucosa during aortic surgery [13] and during CPB [22], we also sought to compare that method with endoluminal microdialysis.…”