A porcine model of systemic and renal haemodynamic responses to infrarenal aortic cross-clamping.

OBJECTIVES: cross-clamping of the infrarenal aorta is associated with complex haemodynamic disturbances. Several experimental models of aortic cross-clamping (AXC) have been described with heterogeneous results. The main purpose of this study was to establish an animal model in which infrarenal AXC could reproduce similar systemic and renal haemodynamic changes to those observed in humans. METHODS: eleven anaesthetised pigs underwent AXC just below the renal arteries. Renal blood flow was measured using clearance of (131)I hippuran. Systemic and renal parameters were collected at 3 consecutive 30-min periods. RESULTS: AXC did not alter the extraction fraction of (131)I hippuran but was accompanied by significant (13%) decrease in cardiac index (p = 0.005) and a 23% increase in mean arterial pressure (p = 0.005). AXC induced significant 135% increase in renal vascular resistance (p = 0.012) and a 35% decrease in renal blood flow (p = 0.016). This worsened after removal of the aortic clamp, whereas systemic variables returned to baseline levels. CONCLUSIONS: this AXC animal model reproduces the changes observed in humans. It provides a reliable animal model which allows to investigate the underlying mechanisms of renal vasoconstriction and the effect of new drugs.