Pancreatic microcirculatory changes in experimental pancreatitis of graded severity in the rat

A technique with two complementary methods, intravital microscopy (IVM) and diffuse reflectance spectroscopy (DRS), was developed to analyze pancreatic tissue perfusion.

After initial in vivo and in vitro validation of the techniques, we studied pancreatic microcirculation in models of mild, moderate, and severe pancreatitis. Anesthetized Sprague-Dawley rats were randomly allocated to the three models or to serve as controls. Stable systemic hemodynamic parameters were maintained with normal saline solution infusion. Exocrine capillary perfusion was assessed by IVM; hemoglobin oxygenation and hemoglobin content were measured by DRS.

Capillary perfusion in mild pancreatitis initially increased significantly at 30 minutes to 155% +/- 38% of baseline values but returned to baseline within 3 hours. Hemoglobin content and oxygen saturation remained stable. In moderate and severe pancreatitis capillary perfusion significantly decreased versus the control group to 12% +/- 6% and 6% (range, 0% to 14%) of baseline values, respectively, at 6 hours. Oxygen saturation decreased significantly in moderate pancreatitis from 48.5% +/- 2.3% to 41.6% +/- 3.5% (p < 0.05) and in severe pancreatitis from 47.2% +/- 1.5% to 38.9% +/- 0.5% (p < 0.05), whereas hemoglobin content did not change.

We conclude that (1) IVM and DRS provide both unique and complementary data on tissue perfusion of the pancreas, (2) that moderate and severe experimental pancreatitis are accompanied by progressive tissue ischemia, and (3) that significant stasis (decreased perfusion) and decreased oxygen saturation occur whereas generalized vasoconstriction (decreased hemoglobin levels) was not found. In contrast, mild experimental pancreatitis was accompanied by initial hyperperfusion and normal oxygen delivery was maintained.