[Haemodynamic and vascular effects of dobutamine during and after open heart operations (author's transl)].

In cardiosurgical patients the haemodynamic effects of dobutamine 2.5 microgram/kg . min and 5 microgram/kg . min dobutamine were investigated during neuroleptanalgesia, intra- and immediately postoperatively. Intraoperative measurements were performed in 8 coronary surgical patients each after sternotomy and pericardiotomy, but before the aortocoronary venous bypass operation. The following haemodynamic parameters increased significantly: cardiac index (2.5 microgram/kg . min: 2.6 leads to 2.1 1/min . m2; 6 microgram/kg . min: 1.5 leads to 2.24 1/min . m2), heart rate (80 leads to 91 min-1; 86 leads to 107 min-1), stroke index (16%, 27%), mean arterial pressure (70 leads to 90 mm Hg; 70 leads to 93 mm Hg), mean pulmonary arterial pressure (8%; 14%), LV dp/dtmax (72%; 121%) and calculated myocardial oxygen consumption Eg (35%; 52%). Changes in right (PRA) and left ventricular filling pressure (PLVED), in total systemic resistance and total pulmonary vascular resistance were not significant. Postoperative measurement immediately after open heart operations (ASD-correction n = 5, aortocoronary venous bypass (n = 3) in neuroleptanalgesia too, showed the same haemodynamic results as intraoperatively before correction of coronary stenosis. Only a few premature ventricular beats were observed in 3 patients and there were no changes in S-T segments during dobutamine infusion. In another group of 15 patients selective vascular responses to an infusion of 10 microgram/kg . min dobutamine were examined during steady state cardiopulmonary bypass excluding heart and lungs from the circulation. No relevant direct influence on the arteriolar resistance vessels and the venous capacitance vessels were found. In a dose range of 2.5--5.0 microgram/kg . min dobutamine proved to be a potent inotropic agent causing almost no peripheral and relatively little positive chronotropic effects. But the increase in heart rate was more pronounced than in other clinical investigations in conscious patients, which might be due to an attenuation of vagal reflex by anaesthesia. The results indicate, that dobutamine may be a valuable drug in the treatment of intra- and postoperative low output syndromes especially in patients with coronary heart disease.