• Marc Licker, Christoph Ellenberger, Jorge Sierra, Jan Christenson, John Diaper, and Denis Morel.
• Department of Anesthesiology, Pharmacology and Surgical Intensive Care, University Hospital of Geneva.
• Crit. Care Med. 2005 Mar 1; 33 (3): 591-7.

ObjectivePreoperative acute normovolemic hemodilution induces an increase in circulatory output that is thought to be limited in patients with cardiac diseases. Using multiple-plane transesophageal echocardiography, we investigated the mechanisms of cardiovascular adaptation during acute normovolemic hemodilution in patients with severe coronary artery disease.DesignProspective case-control study.SettingOperating theater in a university hospital.PatientsConsecutive patients treated with beta-blockers, scheduled to undergo coronary artery bypass (n = 50).InterventionsAfter anesthesia induction, blood withdrawal and isovolemic exchange with iso-oncotic starch (1:1.15 ratio) to achieve a hematocrit value of 28%.Measurements And Main ResultsIn addition to heart rate and intravascular pressures, echocardiographic recordings were obtained before and after acute normovolemic hemodilution to assess cardiac preload, afterload, and contractility. In a control group, not subjected to acute normovolemic hemodilution, hemodynamic variables remained stable during a 20-min anesthesia period. Following acute normovolemic hemodilution, increases in cardiac stroke volume (+28 +/- 4%; mean +/- sd) were correlated with increases in central venous pressure (+2.0 +/- 1.3 mm Hg; R = .56) and in left ventricular end-diastolic area (+18 +/- 5%, R = .39). The unchanged left ventricular end-systolic wall stress and preload-adjusted maximal power indicated that neither left ventricular afterload nor contractility was affected by acute normovolemic hemodilution. Diastolic left ventricular filling abnormalities (15 of 22 cases) improved in 11 patients and were stable in the remaining four patients. Despite reduction in systemic oxygen delivery (-20.5 +/- 7%, p < .05), there was no evidence for myocardial ischemia (electrocardiogram, left ventricular wall motion abnormalities).ConclusionsIn anesthetized patients with coronary artery disease, moderate acute normovolemic hemodilution did not compromise left ventricular systolic and diastolic function. Lowering blood viscosity resulted in increased stroke volume that was mainly related to increased venous return and higher cardiac preload.

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