Preterm Circulatory Support Is More Complex Than Just Blood Pressure

To the Editor .— We agree with Munro et al1 that adequate cerebral blood flow (CBF) is important to protecting the preterm brain, but we disagree that this can be ensured solely on the basis of a mean blood pressure (MBP) of >30 mm Hg. Our studies show a period of vulnerability to low systemic blood flow (SBF) within the first 12 hours; it affects all organs (not just the brain), it is not always shown by low MBP, and it relates strongly to adverse neurologic outcome.2,3 Age of the infant (even within the first 40 hours) is critical …