[Clinical experiences with the acute normovalemic hemodilution (author's transl)]

Abstract

Acute normavolemic hemodilution is a mean of autotransfusion and allow hepatitis prophylaxis in major surgical procedures which general require homologous blood transfusions. The dilutional drop in blood viscosity is followed by an increased cardiac output, while blood pressure and heart rate remain stable. The CO incerase compensates for the reduced oxygen capacity of the diluted blood. Hemodilution was applied in a total of 88 patients. In 46 cases thorough circulatory and laboratory investigations were performed. While an average of 1785 ml blood was withdrawn and replaced synchronically by plasma substitutes, hematocrit was lowered to 24.8% mean and CO rose from 4.4 to 6.01 l/min. In one half of the patients side reactions were observed that occurred in combination as a syndrome in 8 patients: rise in systemic blood pressure and pulmonary artery pressure, disproportional CO increase, peripheral vasoconstriction, and ST-depression in ECG. The possible pathomechanisms of these side reactions are discussed. A sympathetic adrenergic reaction could be excluded by catecholamine estimation. Hyposia may be assumed to be the more probable reason. Since severe side reactions only occured at hematocrit levels below 26%, the dilution waslimited lately to hct 27%. Patients with coronary heart disease, age greater than 70 years, and anemia less than 12 g% hgb were excepted. In 70% of major surgical procedures, e.g. colonic surgery, homologous blood becomes necessary, in 50% in the amount of 2-4 units. The corresponding blood loss of 1000-2000 ml may be compensated by acute normovolemic hemodilution and autotransfusion. In fact, only 15% of our patients required homologous blood transfusions.