HEMODYNAMIC AND RENAL EFFECTS OF DOPEXAMINE AFTER CARDIAC-SURGERY IN CHILDREN

Dopexamine hydrochloride, a synthetic dopamine analog with predominant ly beta and delta agonist properties, has been shown to improve cardia c performance and renal function in adults with heart failure. This st udy was designed to investigate the haemodynamic and renal effects of dopexamine in children after cardiac surgery. Seven children were sele cted in whom a need for postoperative vasodilation after cardiac surge ry was anticipated Haemodynamics and renal function were determined un der baseline conditions and during a continuous infusion of dopexamine at 2 and 6 mu g.kg(-1).min(-1) for 90 minutes, the sequence being ran domized for the initial dose. Cardiac output was measured by thermodil ution and glomerular filtration rate (GFR) and renal plasma flow (RPF) by the clearances of inulin and para-aminohippurate respectively. Dop examine induced a dose-related increase in cardiac index (CI) expresse d as mean (SD) from 3.5 (0.7) to 3.9 (0.76) and 4.5 (0.8) l.min.(-1)m( -2) (both P<0.05), and in heart rate (HR) from 107 (17) to 122 (17) an d 136 (17) beats.min(-1) (P<0.05). Stroke volume index (SVI) and mean systemic pressure were unchanged but pulmonary wedge pressure decrease d from 14 (3) to 11 (4) and 12 (3) mmHg (both P<0.05). Systemic vascul ar resistances (SVR) decreased from 24 (7) to 20 (5) mmHg.l(-1).min(-1 ).m(-2) (P<0.05), with dopexamine 6 mu g.kg(-1).min(-1). Renal blood f low (RBF) increased from 319 (113) to 441 (230) and 410 (138) ml.min(- 1).m(-2) (both P<0.05), GFR from 115 (32) to 142 (34) and 146 (29) ml. min(-1).1.73m(-2) (both P<0.05), urine output and fractional excretion of sodium respectively from 3.12 (2) to 7.16 (8) and 7.21 (6) ml.kg(- 1) (both P<0.05) and from 2.24 (1) to 4.25 (3.4) (P<0.05) and 3.15 (3. 1)% (n.s.). The fraction of CI delivered to the kidneys, the fraction of RBF filtered in the kidneys, plasma renin activity and aldosterone levels remained unchanged. In children after cardiac surgery dopexamin e increases CI at the expense of a concomitant increase in heart rate and demonstrates few selective vascular systemic or intrinsic renal ac tions.