[Hypertonic circulatory response to clinical haemodilution (author's transl)]

Preoperative haemodilution was performed in 46 patients. By exchange of 1785 ml of patient's blood with plasma substitutes, haematocrit was lowered to 24.8% mean. Cardiac output rose, the other circulatry parameters remained constant on average. 8 patients experienced, however, a circulatory reaction with acute systemic and pulmonary hypertension, peripheral vasoconstriction, and ST-depression in ECG. These cases showed a decrease in oxygen uptake. In further 42 patients haemodilution was limited to haematocrit 27%, and only three weak hypertonic reactions were observed. Therefore we recommend haemodilution to be limited to this hematocrit. Saving homologous blood transfusions is the major goal of haemodilution. In comparable surgical procedures 60-70% of patients without haemodilution are given homologous blood. In our two patient groups with haemodilution blood transfusions were necessary in 15 and 21%, respectively. Thus, haemodilution is a valuable mean of hepatitis prophylaxis by saving homologous blood transfusions. This advantage outweighs the possible risks of circulatory reactions.