Cardiopulmonary bypass impairs small intestinal transport and increases gut permeability

Gastrointestinal damage occurs in 0.6% to 2% of patients after cardiopulmonary bypass (CPB), and carries a mortality of 12% to 67%. The incidence of subclinical gastrointestinal damage may be much greater. We examined the effects of nonpulsatile, hypothermic CPB on intestinal absorption and permeability in 41 patients. Bowel mucosal saccharide transport and permeation were evaluated using 100 mL of an oral solution containing 3-O-methyl-D-glucose (0.2 g), D-xylose (0.5 g), L-rhamnose (1.0 g), and lactulose (5.0 g) to assess active carrier-mediated, passive carrier-mediated, transcellular, and paracellular transport, respectively, with a 5-hour urine analysis. Patients were studied before, immediately after, and 5 days after CPB. Immediately after CPB there was a decrease in urinary excretion of 3-O-methyl-D-glucose (from 34% +/- 2.2% to 5.2% +/- 0.7%; p < 0.0001), D-xylose (from 25.4% +/- 1.4% to 4.1% +/- 0.8%; p < 0.0001), and L-rhamnose (from 8.3% +/- 0.6% to 2.6% +/- 0.4%; p < 0.0001). The permeation of 3-O-methyl-D-glucose and D-xylose returned to normal levels 5 days after CPB, but that of L-rhamnose remained significantly below pre-CPB values at 6.6% +/- 0.5% (p = 0.004). However, the permeation of lactulose increased after CPB (from 0.35% +/- 0.04% to 0.59% +/- 0.1%; p = 0.018), and the lactulose/L-rhamnose gut permeability ratio increased markedly (from 0.045 +/- 0.04 to 0.36 +/- 0.08; normal = 0.06 to 0.08; p = 0.004). Patients who had a CPB time of 100 minutes or more had a greater increase in gut permeability (p = 0.049).(ABSTRACT TRUNCATED AT 250 WORDS)