The Effects of Thoracic Aortic Cross-Clamping and Declamping on Visceral Organ Blood Flow

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Abstract
Blood flow measured using radioactive microspheres in 11 macaque monkeys before hemorrhagic shock, after onset of shock, after aortic cross-clamping and resuscitation and after release of the cross-clamp and stabilization. Hemodynamic parameters (cardiac output, arterial, right atrial and left atrial pressure) and blood gases were also monitored. Total abdominal organ flow fell with hemorrhage and fell further with aortic clamping. Reinfusion of shed volume did not restore abdominal organ flow (4.7% baselines) but increased LAP [left atrial pressure] and cardiac output to the upper body. Release of the cross-clamp produced profound acidosis that was treated effectively with NcHCO3. After stabilization of blood, flow to kidney remained low (49% baseline) although intestinal flow was increased 3 fold (320% of baseline). Apparently, thoracic aortic cross-clamping in shock further compromises already reduced visceral blood flow and may contribute to the problem of ischemic multiple organ failure after resuscitation from hemorrhagic shock.