Renal blood flow in high and low positions of aortal catheter in rabbits

The effect of aortal catheterization on renal blood flow (RBF) was evaluated in seven rabbits weighing 2500 to 3500 g. RBF was measured 21 times from 13 kidneys during aortal catheterization with an isotope (133 Xe) technique. The catheter was positioned in the aorta of each rabbit both above and below the origins of the renal arteries. The results of these two measurements were compared. Two phases of RBF, a fast first phase and a slow second phase, were determined. The fast phase of RBF was 5.3 ml/g/min, when it was in the high position. The results of the slow phase were identical, 0.16 ml/g/min, in both positions. No significant statistical difference could be found according to the phase of the catheter (paired t-test). These results in rabbits suggest that the aortal catheter does not cause any immediate decrease in RBF. This finding has clinical importance in aortal catheterization in neonates to obtain arterial blood samples. When considering the position of the aortal catheter in neonates factors other than RBF should be taken into account.