Impairment of pancreatic microcirculation correlates with the severity of acute experimental pancreatitis.

BACKGROUND

Altered microcirculatory perfusion may be an important factor in the pathogenesis of necrotizing pancreatitis. Diffuse reflectance spectroscopy (DRS) can measure dynamic alterations in the microcirculation over a larger area than intravital microscopy.

STUDY DESIGN

We used DRS to characterize changes in the microcirculation during the evolution of pancreatitis of varying severity. Male Sprague Dawley rats (330 to 400 g) were randomly allocated to four groups: control (n = 18), mild pancreatitis (n = 18), moderate pancreatitis (n = 18), or severe pancreatitis (n = 34). Within each group, rats were studied 0.5, 3.0, or 6.0 hours after induction of pancreatitis to determine total hemoglobin content (IHb) and hemoglobin oxygenation (ISO2).

RESULTS

Total hemoglobin content in the pancreas remained constant in all groups. Hemoglobin oxygenation increased significantly in rats in the control group and in rats with mild pancreatitis for the duration of the experiment, but not in rats with moderate or severe pancreatitis. Rats with severe pancreatitis had a significant decrease in ISO2 six hours after the induction of pancreatitis compared with baseline values (49.18 +/- 1.55 versus 52.01 +/- 0.19, p < 0.01) as well as rats in the control group that were studied after six hours (49.18 +/- 1.55 versus 55.92 +/- 1.07, p < 0.02). Furthermore, there was marked variability in IHb and ISO2 at different locations within the same pancreas in rats with severe pancreatitis, which was not observed in the control group or in the rats with mild or moderate pancreatitis.

CONCLUSIONS

Impaired microcirculatory perfusion characterizes severe, but not mild, pancreatitis. The predominant early change is stasis rather than vasoconstriction. As the changes become more severe, necrosis occurs in a heterogeneous distribution.