Dopamine effects on infant pulmonary and systemic vasculature

The effects of dopamine on pulmonary and systematic vascular beds were investigated in 8 anesthetized goats (mean age 5±1 weeks). Pulmonary artery, aortic, left atrial, and central venous pressures and pulmonary and aortic flows were recorded simultaneously during a 10-minute baseline period and while infusion dopamine at 5, 10, 20, 40 160, and 320 μg/kg/min. Pulmonary vascular resistance increased significantly at the 20 and 40 μ/kg/min infusion rates, while systemic vascular resistance decreased significantly at these rates. Characteristic impedances indicate generally increased trends. The pulmonary global reflection index indicates increased impedance mismatch at the high infusion rates, while the opposite is true for the systemic reflection index. Right heart work and the energy costs of transporting 1 cm³ blood exceed systemic work and energy costs at the high rates of increase the resting tone of the pulmonary vascular bed, while the effect on systemic vascular tone remains unclear. The finding that the work and energy requirements of the heart are substantially increased at the higher infusion rates could affect the therapeutic value of dopamine use at these rates