INTRAVENOUS CONTRAST-MEDIUM IMPAIRS OXYGENATION OF THE PANCREAS IN ACUTE NECROTIZING PANCREATITIS IN THE RAT

Objective: Contrast-enhanced computed tomography is widely used to eva luate severe acute necrotizing pancreatitis (ANP) by demonstrating are as of malperfusion, which might indicate irreversible necrosis. Becaus e of our prior finding that the intravenous contrast medium (CM) accen tuates the severity of ANP by promoting further necrosis and higher mo rtality, we sought to investigate the mechanism by which this injury i s mediated. Resign: Mild acute pancreatitis was induced in Sprague-Daw ley rats with intravenous caerulein hyperstimulation; and severe ANP, with intravenous caerulein plus intraductal glycodeoxycholic acid. Con trol animals and rats with pancreatitis were randomized to be given in travenous CM or saline. Main Outcome Measure: Diffuse reflectance spec troscopy was used to measure the index of hemoglobin content and oxyge n saturation in pancreatic tissues in vivo. Results: Oxygen saturation of hemoglobin was increased in animals with mild acute pancreatitis ( AP) (mean [+/-SEM], 58.7% +/- 1.2% vs 55.2% +/- 1.5% in control animal s; P<.05) and was decreased in animals with ANP (51.2% +/- 1.2% vs 55. 2% +/- 1.5%; P<.05). Fifteen minutes after the infusion of CM, oxygen saturation of hemoglobin significantly decreased further in animals wi th ANP (51.4% +/- 1.8% before infusion of CM vs 46.1% +/- 1.7% at 15 m inutes; P<.05) and remained significantly below the comparable group r eceiving intravenous saline for the entire 60-minute test. This decrem ent was not observed in animals with ANP given saline or in animals wi th mild AP or in control animals after infusion of saline or CM. The i ndex of hemoglobin content remained unchanged throughout the experimen t in all groups. Conclusions: The prolonged reduction of oxygen satura tion of hemoglobin in the pancreas following the administration of int ravenous CM in rats with severe ANP indicates that CM impairs the panc reatic microcirculation in necrotizing forms of AP. This may explain o ur previous finding that CM increases pancreatic injury and mortality in rodents with ANP, and it underlines our concern that the use of con trast-enhanced computed tomography early in human AP may promote the e volution of pancreatic necrosis.