PANCREATIC MICROCIRCULATORY CHANGES IN EXPERIMENTAL PANCREATITIS OF GRADED SEVERITY IN THE RAT

Background. A technique with two complementary methods, intravital mic roscopy (IVM) and diffuse reflectance spectroscopy (DRS), was develope d to analyze pancreatic tissue perfusion. Methods. After initial in vi vo and in vitro validation of the techniques, we studied pancreatic mi crocirculation in models of mild, moderate, and severe pancreatitis. A nesthetized Sprague-Dawley rats were randomly allocated to the three m odels of to serve as controls. Stable systemic hemodynamic parameters were maintained with normal saline solution infusion. Exocrine capilla ry perfusion was assessed by IVM; hemoglobin oxygenation and hemoglobi n content were measured by DRS. Results. Capillary perfusion in mild p ancreatitis initially increased significantly at 30 minutes to 155% +/ - 38% of baseline values but returned to baseline within 3 hours. Hemo globin 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 signifi cantly 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. Conclusio ns. We conclude that (1) IVM and DRS provide both unique and complemen tary data on tissue perfusion of the pancreas, (2) that moderate and s evere experimental pancreatitis are accompanied by progressive tissue ischemia, and (3) that significant stasis (decreased perfusion) and de creased oxygen saturation occur whereas generalized vasoconstriction ( decreased hemoglobin levels) was not found. In contrast, mild experime ntal pancreatitis was accompanied by initial hyperperfusion and normal oxygen delivery was maintained.