Gastrointestinal Blood Flow in the Dog

• Measurement of blood flow to the indi-vidual gastrointestinal organs has been ham-pered by limitations of methodology. The old-est and most direct experimental technique for estimating blood flow to an organ is timed collection of its total venous outflow. Trau-matic surgical procedures are required to accomplish such collections from the stomach, intestine, or colon. This method is not appli-cable to the pancreas, gall bladder, duode-num or esophagus because these latter or-gans are drained by multiple small vessels. Placement of flowmetering devices on or in the major vessels also requires relatively ex-tensive operative manipulation. The complex-ity of the arterial inflow and venous outflow pathways of the gastrointestinal organs makes estimates for an individual organ by means of a flowmeter somewhat questionable. Fur-thermore, the flowmeter devices, whether based on thermal or electromagnetic princi-ples, are generally more useful for estimating relative changes in blood flow than for deter-mining absolute quantities. In recent years indicator clearance tech-niques have been developed which allow measurement of tissue blood flow with rela-tively little disturbance of normal function. The particular method used in the present study was the radiorubidium distribution technique. The first part of the investigation was an inquiry into the suitability of this method for measurement of blood flow to the various gastrointestinal organs. The method gave ac-curate estimates of total blood flow to the stomach, small intestine and colon. Indirect evidence suggested that it was probably suit-able for pancreas, gall bladder and esoph-agus. In the second part of the study th