Blood flow measurement in the canine pancreas

Blood flow in the anesthetized animal has been measured indirectly by plethysmography and directly with the stromuhr, venous outflow, and electromagnetic flow techniques. Tissue perfusion in the gland has been assessed qualitatively with thermocouples and quantitatively by isotope fractionation, the distribution of microspheres, hydrogen desaturation, and clearance of either 133Xe or 85Kr. The results of these investigations have been conflicting as there is a large variation in both flow and perfusion measurements, not only overall but also in the values reported by each technique (Table 1). Taking all methods into account flow measurements have been recorded from 9 to 63 (mean 29.8) ml/min, and 10 to 200 (mean 66.1) ml/min/100 g. The mean percentage of the cardiac output distributed to the pancreas is 1.28. Some of these differences are due to various drawbacks associated with each of the techniques; some are almost certainly due to variations in the surgical preparations, and others are undoubtedly caused by the complexity of the pancreatic circulation. Measurements of perfusion in different regions of the pancreas of individual dogs show no difference if all vessels are intact, but accessory vessel ligation affects perfusion in certain areas. In ambulant dogs the studies suggest that pancreatic blood flow is higher than in the anesthetized animal. This is probably true despite inaccuracies associated with each of the techniques. In addition to this drawback there is also the problem of obtaining measurements with the dogs in a relaxed state. It is probably for this reason that the majority of investigators have preferred to examine blood flow and perfusion in the canine pancreas in the anesthetized animal. It is not possible to make a definitive statement regarding the best model and measurement technique available to measure blood flow or tissue perfusion in the canine pancreas. The choice should undoubtedly be governed by the aims of the proposed study. In studies of tissue perfusion in the intact gland, it is obviously preferable that all vessels should be intact, as division of any vessels supplying the gland has been shown to affect perfusion in certain areas. Measurements in such a preparation could be taken using the 85Kr clearance technique, with a flow probe placed around the gastroduodenal artery to ensure stable flow during measurements. It is difficult to assess total arterial blood flow to the whole gland due to the number of vessels supplying the organ.(ABSTRACT TRUNCATED AT 400 WORDS)