CI = cardiac index; EO 2 = oxygen extraction; HAFI = hepatic arterial flow index; hepatic DO 2 = hepatic oxygen delivery; hepatic DO 2 ratio = ratio of hepatic arterial oxygen delivery to total hepatic oxygen delivery; MVRI = mesenteric vascular resistance index; PAP = mean pulmonary arterial pressure; PVFI = portal venous flow index; PVRI = pulmonary vascular resistance index; S a O 2 = arterial saturation; SAP = mean systemic arterial pressure; S p O 2 = portal venous saturation; S v O 2 = mixed venous saturation; SVRI = systemic vascular resistance index; VO 2 = oxygen consumption; THFI = total hepatic flow index.Available online http://ccforum.com/content/5/3/158
AbstractBackground: The most appropriate inotropic agent for use in the newborn is uncertain. Dopamine and epinephrine are commonly used, but have unknown effects during hypoxia and pulmonary hypertension; the effects on the splanchnic circulation, in particular, are unclear. Methods: The effects on the systemic, pulmonary, hepatic, and mesenteric circulations of infusions of dopamine and epinephrine (adrenaline) were compared in 17 newborn piglets. Three groups [control (n = 5), dopamine (n = 6) and epinephrine (n = 6)] of fentanyl anesthetized newborn piglets were instrumented to measure cardiac index (CI), hepatic arterial and portal venous blood flow, mean systemic arterial pressure (SAP), mean pulmonary arterial pressure (PAP), and arterial, portal and mixed venous oxygen saturations. Systemic, pulmonary, and mesenteric vascular resistance indices [systemic vascular resistance index (SVRI), pulmonary vascular resistance index (PVRI), mesenteric vascular resistance index (MVRI)], and systemic and splanchnic oxygen extraction and consumption were calculated. Alveolar hypoxia was induced, with arterial oxygen saturation being maintained at 55-65%. After 1 h of stabilization during hypoxia, each animal received either dopamine or epinephrine; randomly administered doses of 2, 10, and 32 µg kg -1 min -1 and 0.2, 1.0, and 3.2 µg kg -1 min -1 respectively were infused for 1 h at each dose. Results were compared with the 1 h hypoxia values by two-way analysis of variance. Results: Epinephrine increased CI at all doses, with no significant effects on SAP and SVRI. Although epinephrine increased PAP at 3.2 µg kg -1 min -1 , it had no effect on PVRI. Dopamine had no effect on CI, SAP, and SVRI, but increased PAP at all doses and PVRI at 32 µg kg -1 min -1 . The SAP/PAP ratio was decreased with 32 µg kg -1 min -1 dopamine, whereas epinephrine did not affect the ratio. In the mesenteric circulation, dopamine at 32 µg kg -1 min -1 increased portal venous flow and total hepatic blood flow and oxygen delivery, and decreased MVRI; epinephrine had no effect on these variables. Epinephrine increased hepatic arterial flow at 0.2 µg kg -1 min -1 ; dopamine had no effect on hepatic arterial flow at any dose. Despite these hemodynamic changes, there were no differences in systemic or splanchnic oxygen extraction or consumption at any dose of dopamine or epinephrine. ...