Comparative study of effects of adrenaline, dobutamine and dopamine on systemic hemodynamics and renal blood flow in patients following open heart surgery

Abstract

In 10 patients following open heart surgery, adrenaline, dobutamine and dopamine were administered, and the changes in hemodynamic parameters and renal blood flow (RBF) were examined. RBF was determined by the local thermodilution method. Prior to the application of this method in clinical measurement, reliability of the method was checked using a model circuit. The correlation between the actual flow and flow obtained with this method was high (r = 0.999, p less than 0.005, n = 8). Reproducibility in repeated measurements was excellent, r = 0.997 (p less than 0.005, n = 8) in the model circuit and r = 0.985 (p less than 0.005, n = 89) in the clinical measurement. Adrenaline at rates of 0.02--0.08 microgram/kg/min showed a marked inotropic action without any significant change in RBF. With 0.04 microgram/kg/min of adrenaline, the RBF/CO (cardiac output) ratio declined significantly. We conclude that adrenaline is often effective in patients following open heart surgery, but renal vasoconstriction is the major disadvantage. After a 10-min administration of 2, 4 and 8 micrograms/kg/min of dobutamine, cardiac index (CI) and stroke volume index (SVI) showed a stepwise increase in accordance with an increase of dosage, and RBF also increased with CO. Consequently, no significant change in RBF/CO was found. Mean left atrial pressure (LAP) or mean pulmonary arterial wedge pressure (PAWP) decreased in 4 of 7 patients with 8.0 micrograms/kg/min of dobutamine. Thus, dobutamine is an excellent beta 1-adrenergic agonist with a weak alpha-action on both peripheral and renal vessels. With 2.0--2.5 micrograms/kg/min of dopamine, RBF increased by 15.5% (p less than 0.05). while no significant increase appeared in CI. With 4.0 micrograms/kg/min or more of dopamine, CI and SVI increased. With 16--20 micrograms/kg/min of dopamine, RBF increased by up to 44.8%. Significant increase of mean LAP or mean PAWP was observed with 8.0--10.0 micrograms/kg/min or more of dopamine. These findings indicate that the potential increase o LVEDP (left ventricular end-diastolic pressure) with 8--10 micrograms/kg/min or more of dopamine exerts a disadvantageous effect in patients following open heart surgery. However, the effect on the renal hemodynamics, especially with small doses of dopamine, is unique and not observed with adrenaline or dobutamine.