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

To compare changes in global haemodynamics as well as anterior cerebral and superior mesenteric artery perfusion after dopamine treatment.

Anterior cerebal and superior mesenteric artery perfusion was measured using Doppler ultrasonography in hypotensive preterm neonates in whom cardiac output increased (group 1, n=10) or decreased (group 2, n=40) after dopamine treatment.

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 cerebral artery blood velocity and resistance were unaffected by dopamine. However, 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.

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 bowel perfusion.