on a piglet 39 s body fig4 illustrates a test where sensors 6 16 were placed over the gut target area and leg reference area of a piglet blood flow to the gut was interrupted causing a drop in tissue hemoglobin oxygen saturation expressed as rso2 in the gut but not in the leg from the display shown in fig4 it could be determined that the cause of the change in oxygen saturation in the gut was caused by a local tissue specific condition fig5 illustrates a test where an oximeter having four sensors such as sensors 6 and 16 in fig1 2 was used and the sensors were placed over the kidney target area head gut and leg reference areas of a piglet blood flow to the kidney was interrupted causing a drop in tissue hemoglobin oxygen saturation in the kidney expressed as rso2 but not in the leg head or gut from the display shown in fig5 it could be determined that the cause of the change in oxygen saturation in the kidney was caused by a local tissue specific condition fig6 illustrates a test where an oximeter having four sensors was used and the sensors were placed over the right kidney target area left leg right abdomen and the head reference areas of a piglet sequential blood draws of 20 cc were performed reducing the amount of blood available to perfuse the tissues and hence decreasing the amount of hemoglobin bound oxygen delivered to the tissues which caused the tissue hemoglobin oxygen saturation in all four tissues to drop in parallel the blood was sequentially reinfused into the femoral artery in 20 cc aliquots causing.