Preterm newborns often receive IV dopamine to support their mean arterial blood pressure (MAP), but there is little data regarding their cerebrovascular responses. Using chronically-catheterized fetal sheep, we tested the hypothesis that IV dopamine causes dose-dependent cerebral vasoconstriction in immature fetuses. We measured cerebral blood flow (CBF-radiolabeled microspheres) and calculated cerebrovascular resistance (CVR) and cerebral O2 delivery (OD) in seven near-term ( 132 ± 1d) and eight preterm (93 ± 1d) fetal sheep, two days after catheter placement. Measurements were made at baseline and at four fetal dopamine infusion rates: 2.5, 7.5, 25 and 75 μg/kg/min. Results: (mean ± SEM)Rate Percent Change (compared to baseline) μg/kg/min MAP CBF CVR HR OD 93d 25 10 ± 2% No Δ 76 ± 51% 23 ± 3% No Δ 75 25 ± 5 No Δ 80 ± 33 21 ± 4 No Δ 132d 25 29 ± 4 No Δ 41 ± 12 No Δ No Δ 75 55 ± 3 No Δ 87 ± 23 No Δ No Δ Dopamine, at doses high enough to raise MAP at least 10% above baseline, causes cerebral vasoconstriction in both preterm and near term fetal sheep. This response could be detrimental to cerebral perfusion and O2 delivery, particularly during hypoxia/ischemia.
|Original language||English (US)|
|State||Published - Mar 20 1998|
ASJC Scopus subject areas
- Molecular Biology