[Myocardial oxygen supply in hemodilution in patients with healthy hearts and heart surgery patients].
Infusion of colloid solutions for intentional isovolemic hemodilution can help to save homologous blood in surgical patients. In addition, hemodilution improves blood fluidity which leads to an increased organ blood flow and better tissue oxygenation. A major limiting factor for the degree of dilutional anemia induced by hemodilution is the oxygen supply of the myocardium since unimpaired heart function is of utmost importance. The basic mechanism that compensates for the reduction of hemoglobin-concentration (fall of oxygen capacity) of the diluted blood is a rise in cardiac output and coronary blood flow which maintains or even enhances systemic and coronary oxygen transport capacity (hemoglobin-concentration x saturation x cardiac output or coronary blood flow). In normovolemic patients with unimpaired cardiac function there is no problem in this respect and clinical experience has shown that even high degrees of dilutional anemia are well tolerated. Patients with heart disease, however, may have a limited ability to increase cardiac output and coronary blood flow. Therefore, in these cases the risks of intentional hemodilution can exceed its benefits and a careful evaluation of risks is mandatory for every individual patient. In the following, we review knowledge from the literature and our own experimental and clinical data to explain the influence of dilutional anemia on the physiology and pathophysiology of myocardial oxygen supply.
Klinik für Herz- und Gefässchirurgie, Deutsches Herzzentrum München.
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Klövekorn
D001026:Coronary Artery Bypass; D003327:Coronary Disease / Q000097:blood / Q000601:surgery*; D006438:Hemodilution / Q000379:methods*; D006801:Humans; D009206:Myocardium / Q000378:metabolism*; D010100:Oxygen / Q000097:blood*
D010100:Oxygen
Die myokardiale Sauerstoffversorgung unter Hämodilution bei herzgesunden und -chirurgischen Patienten.