Pressure, volume and the pancreas.

The effects of injection volume and pressure on the rat pancreas have been investigated. An experimental model using transduodenal cannulation of the rat bile-pancreatic duct was used. Injection volumes of 100 microliter or above produced gross ductal extravasation regardless of pressure. With a 50 microliter volume leakage from the ducts occurred via intercellular clefts at a pressure of 20 cmH2O and via duct ruptures at 50 cmH2O. Survival experiments (24 hours) were carried out using the 50 microliter volume. Infusion of 50 microliter saline at increasing pressures produced rises in amylase concentrations, pancreatic gland weights and water content of the gland at pressures of 20 cmH2O or above. These changes were maximal when 50 cmH2O of pressure was maintained for 60 minutes. The changes correlated with extravasation shown by Indian ink. Histological oedema related closely to pressure (r = 0.92), and was the most pronounced histological change observed. In experiments using intraduct injection into the rat pancreas a volume of 50 microliter or less should be used with careful consideration given to pressure. Unless these prerequisites are followed the results of experimental investigation cannot be extrapolated to acute gall stone pancreatitis in man.