Mechanisms of blood pressure increase induced by dopamine in hypotensive preterm neonates

Aims-To compare changes in global haemodynamics as well as anterior cerebra l and superior mesenteric artery perfusion after dopamine treatment. Methods-Anterior cerebal and superior mesenteric artery perfusion was measu red using Doppler ultrasonography in hypotensive preterm neonates in whom c ardiac output increased (group 1, n=10) or decreased (group 2, n=40) after dopamine treatment. Results-Despite a lower dopamine infusion rate, the blood pressure increase (mm Hg) in group 2 [Delta=13(1); mean(SE)] exceeded that in group 1 [Delta =8(1)], while systemic vascular resistance (mm Hg/l/min/kg) rose in group 2 [Delta=106 (37)], but was unchanged in group 1 [Delta=9 (6)]. Anterior cer ebral artery blood velocity and resistance were unaffected by dopamine. How ever, compared with unchanged values in group 1, superior mesenteric artery blood velocity fell by 14.7(4.8) cm/s and resistance increased by 4.1(0.7) mm Hg/cm in group 2. Conclusions-These results suggest that, in a portion of hypotensive preterm neonates, the increase in blood pressure induced by dopamine is related to a predominant vasoconstrictor action and is associated with a fall in bowe l perfusion.