Effects of intraaortic balloon position on renal artery blood flow

Debate continues over what happens to renal blood flow when intraaortic balloons are adjacent to the renal arteries. Fourteen dogs were prepared by implanting instruments to measure heart rate; right atrial, pulmonary arterial, carotid arterial, and femoral arterial pressures; cardiac index; mixed venous oxygen saturation; urine output; and left and right renal blood flows. A 12-mL intraaortic balloon was inserted through the left (n = 9) or right (n = 5) femoral artery. The position of the balloon was randomized so that it was initially placed in either the control (thoracic) or renal position (at the level of the renal arteries). Intraaortic balloon pumping was performed for 4 hours in each position. In 8 dogs, at least one of the renal arteries had partial occlusion, 23% to 98% decrease in flow (mean decrease, 66%), while the intraaortic balloon was in the renal position. An intraaortic balloon in the renal position results in lower renal blood flow as well as a high risk (57%) of selective renal artery occlusion. Decreased renal blood flow is not apparent using conventional monitoring, as hemodynamics do not change.