Abstract

Background: The extent to which microcirculation in the small intestine decreases following ischaemia and reperfusion of the liver is not known to date. The present study aims to examine the pathophysiological effects of hepatic ischaemia on the microcapillary perfusion of the small intestine in a rat model. Method: Under anaesthesia (pentobarbital 50 mg/kg), Wistar rats underwent laparotomy with continuous haemodynamic monitoring. Ischaemia of the left hepatic lobe was induced by clamping the supplying blood vessels for a period of 40-min followed by 60-min reperfusion. The control group was prepared in a similar fashion without clamping of liver vessels. Micro circulatory parameters such as functional capillary density (FCD [cm^-1]), both in the mucosa as well as in the muscularis, red blood cell velocity (RBCV [mm/s]), perfusion index (PI) and leukocyteendothelial interactions (LEI [Stickers/mm²]) were determined for the small intestine using intravital microscopy (plasma stain, FITC-dextran; leukocyte stain, rhodamine 6G). Significant differences were calculated using the Wilcoxon test (mean ± SEM). Results: The FCD of the small intestine following ischaemia and reperfusion of the left hepatic lobe (I/R group) showed a significant reduction in comparison with the control group in both the mucosa (I/R 515 ± 20 vs. control 770 ± 18 [cm^-1];p < 0.01) and the muscularis (I/R 272 ± 9 vs. control 320 ± 5 [cm^-1]; p < 0.01). In parallel, the PI was significantly decreased (I/R 0.68 ± 0.025 vs. control 0.93 ± 0.013; p < 0.01). The RCBV was significantly lower in the I/R group than in the control group (I/R 0.35 ± 0.007 vs. control 0.49 ± 0.013 [mm/s]; p < 0.01). Accordingly, LEI were significantly more frequent in the I/R group (I/R 544 ± 54 vs. control 310 ± 37 [Sticker/mm²]; p < 0.01). Conclusion: Following ischaemia and reperfusion of the left hepatic lobe in a rat model, it may be shown that profound alterations in the FCD, RBCV, PI and LEI occur in the small intestine in comparison with the control group. The changes in microvascular perfusion of the small intestine indicate that not only primary shock organs such as the lung and kidney may be affected by ischaemia-reperfusion damage to a remote organ system. On the contrary, on the basis of the present intravital microscopic study, we find a microvascular correlation with frequently described postoperative functional disorders of the small intestine up to increased resorption of enterotoxins. As such, the protection of intestinal function appears to be of importance in hepatobiliary surgery as well. Preoperative preparation of the intestine should be considered in cases of extended periods of ischaemia.