Adverse effects of dopamine on systemic hemodynamic status and oxygen transport in neonates after the Norwood procedure

OBJECTIVES The purpose of this study was to evaluate the effects of dopamine on hemodynamic status and oxygen transport in neonates after the Norwood procedure. BACKGROUND Dopamine is widely used to augment cardiac performance and increase oxygen delivery (Do(2)) in patients after cardiopulmonary bypass (CPB). This might be at the expense of increased myocardial and systemic oxygen consumption (Vo(2)), thus offsetting the improved Do,. This balance is particularly fragile in critically ill neonates. METHODS Systemic oxygen consumption was continuously measured with respiratory mass spectrometry in 13 sedated, paralyzed, and mechanically ventilated neonates for 72 h after the Norwood procedure. Arterial, superior vena caval, and pulmonary venous blood gases were measured to calculate pulmonary blood flow (Q(p)) and systemic blood flow (Q(s)), Do(2) and oxygen extraction ratio (ERo(2)). Rate-pressure product was calculated. Dopamine at a dose of 5 mu g/kg/min was routinely administered at cessation of CPB and terminated within the first 48 h. Hemodynamic and oxygen transport measures were obtained before and at 100 min after the termination of dopamine. RESULTS Terminating dopamine was not associated with significant changes in arterial pressure, Q(p) Q(s) or Do(2) but was associated with a significant decrease in heart rate (p = 0.003), rate-pressure product (p = 0.03), and Vo(2) (-20 +/- 11%, p < 0.0001), resulting in a significant decrease in ERo(2) (P = 0.01). CONCLUSIONS Dopamine induces a significant increase in Vo(2) in neonates after the Norwood procedure, and termination is associated with an improved balance of Vo(2)-Do(2). These data further emphasize the importance of understanding changes in Vo(2) as well as Do(2) in infants after cardiac surgery.