SYSTEMIC, PULMONARY AND MESENTERIC PERFUSION AND OXYGENATION EFFECTS OF DOPAMINE AND EPINEPHRINE

The response of the systemic, pulmonary, hepatic and portal circulatio ns to infusion of dopamine and epinephrine was studied in newborn pigl ets 1 to 3 d of age. Anesthetized animals were instrumented to measure cardiac index (CI), hepatic arterial Row, and portal venous blood flo w. Catheters were inserted for measurement of systemic arterial pressu re (SAP), pulmonary arterial pressure (PAP), and for sampling of arter ial, portal venous, and mixed venous oxygen saturations and plasma lac tate levels. Systemic, pulmonary and mesenteric vascular resistance in dices (SVRI, PVRI, MVRI), and systemic and mesenteric oxygen extractio n were calculated. Dopamine and epinephrine were infused in doses of 2 , 10, 32 mu g/kg/min and 0.2, 1.0, 3.2 mu g/kg/min respectively, given in random order. Significant increases in SAP, PAP, and CI were demon strated with 32 mu g/kg/min of dopamine and the two higher doses (1.0 and 3.2 mu g/kg/min) of epinephrine. There were no significant changes in SVRI and PVRI with dopamine infusions. Epinephrine at 3.2 mu g/kg/ min significantly elevated SVRI and PVRI. The SAP/PAP ratio was decrea sed with 32 mu g/kg/min of dopamine whereas epinephrine did not affect the ratio. Dopamine had no significant effect on hepatic arterial Row , portal venous Row, or mesenteric vascular resistance. Epinephrine in fusion at 3.2 mu g/kg/min decreased portal venous blood Row, total hep atic blood Row, and hepatic oxygen delivery with an increase in calcul ated mesenteric vascular resistance. Systemic and mesenteric oxygen ex traction were not affected by dopamine or epinephrine infusions. Plasm a lactate levels were significantly elevated with epinephrine infusion 3.2 mu g/kg/min. The differential responses of dopamine and epinephri ne on pulmonary and mesenteric circulations may be significant in the pathophysiology and management of persistent fetal circulation and nec rotizing enterocolitis.