European surgical research. Europäische chirurgische Forschung. Recherches chirurgicales européennes
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The myocardial (arterial-coronary sinus) balance of oxygen and lactate was studied before a cardiopulmonary bypass and during the first 5 min of a normothermic bypass in two patient groups undergoing coronary revascularization for multiple coronary artery disease. The hemodilution (HD) group was hemodiluted before the bypass with dextran 70 (15 ml/kg; resulting mean hematocrit 32%) and further at the beginning of the bypass due to nonhemic priming of the oxygenator (mean hematocrit 15%). The control (C) group was not diluted before the bypass, and four units of red blood cells were included in the oxygenator priming (mean hematocrit 27% after the beginning of the bypass). ⋯ Hypotension frequently accompanied the beginning of the bypass in both groups. It is concluded that the hemodilution to a hematocrit level of 32% in patients undergoing coronary revascularization for multiple stable coronary artery disease produces compensatory changes in myocardial oxygen extraction, but no changes of a generalized ischemia can be demonstrated. The hemodilution to a hematocrit level of 15% produces myocardial ischemia in patients with a normothermic unloaded heart, adding to the effect of hypotension at the beginning of the bypass.