Figure 52-11 Systemic hemodynamic response to aortic cross-clamping. Preload (asterisk) does not necessarily increase with infrarenal clamping. Depending on splanchnic vascular tone, blood volume can be shifted into the splanchnic circulation, and preload does not increase. Ao, aortic; AoX, aortic cross-clamping; R art, arterial resistance. (Adapted from Gelman S: The pathophysiology of aortic cross-clamping and unclamping. Anesthesiology 82:1026–1060, 1995.)