A comparison of combination dopamine and epinephrine treatment with high-dose dopamine alone in asphyxiated newborn piglets after resuscitation

BACKGROUND: When asphyxiated neonates require additional cardiovascular support to moderate doses of dopamine infusion, controversy exists on differential hemodynamic effects of two approaches (adding a second inotrope vs. increasing dopamine dosage). We hypothesized that high-dose dopamine (HD) would be detrimental on systemic and regional perfusion when compared with dopamine and epinephrine (D+E) combination therapy using a swine model of neonatal hypoxia-reoxygenation (H-R). METHODS: Twenty-seven piglets (1–4 days, 1.5–2.5kg) were used for continuous monitoring of systemic (MAP) and pulmonary (PAP) arterial pressures, cardiac output (CI) and carotid (CAFI), superior mesenteric (SMAFI) and renal arterial flows. H-R piglets underwent 2h of hypoxia followed by 2h of reoxygenation prior to drug infusion (2h). RESULTS: The hemodynamics of H-R piglets deteriorated gradually after reoxygenation. HD and D+E infusions improved CI similarly (both groups vs. control; p<0.05). Both regimens increased MAP (p<0.05) but not PAP, with decreased PAP/MAP ratio in D+E piglets. Both regimens improved CAFI and SMAFI with decreased mesenteric vascular resistance in HD-treated piglets. No significant effect on renal perfusion was observed. CONCLUSION: In H-R newborn piglets treated with a moderate dose of dopamine, adding epinephrine or further increasing dopamine improved systemic hemodynamics similarly, and have differential effects on the pulmonary and mesenteric circulations.