Dopamine therapy promotes cerebral flow-metabolism coupling in preterm infants

Dopamine is widely used to maintain blood pressure in very preterm infants, but it may affect neurovascular regulation as it crosses the immature blood-brain barrier. We contrasted the relationship between cerebral perfusion and oxygen metabolism in preterm infants treated with dopamine because of hypotension with normotensive controls.

Prospective observational study in a neonatal intensive care unit.

Cerebral metabolic rate of oxygen consumption (CMRO2) was determined via measurements of cerebral blood flow (CBF) and cerebral venous saturation (CSvO2) using near infrared spectroscopy. Twenty-six infants (median gestation 26 weeks) were studied at a median postnatal age of 17 h. Infants were categorised as control (n = 16) or dopamine-treated (DOPA, n = 10).

No relationship was found between CBF and CMRO2 in the control group, while a strong positive correlation was found in the DOPA group (R (2) = 0.62, P = 0.01). Cerebral fractional oxygen extraction (CFOE) and CBF showed strong negative correlation in the control infants (R2 = 0.65, P < 0.001), but not in the DOPA group. CSvO2 was lower at decreased CBF (R2 = 0.56, P < 0.001) in the control infants, but not in the DOPA group.

Cerebral blood flow-metabolism coupling in the very preterm brain differs strikingly from that in the mature brain, where CBF is coupled to CMRO2. In the very preterm brain, variations of cerebral oxygen extraction, not CBF, sustain CMRO2. In contrast, preterm infants receiving dopamine exhibit flow-metabolism coupling similar to the mature brain. These findings suggest a previously unrecognised role for dopamine in the preterm brain in promoting flow-metabolism coupling.