Chapter 1 - Cerebral Circulation and Hypotension in the Premature Infant: Diagnosis and Treatment

Abstract

Despite advances in our understanding of developmental hemodynamics and our ability to better monitor the cardiovascular status in neonates, the definition of the “normal” gestational age– and postnatal age–dependent blood pressure range has remained an elusive target. In fact, as a blood pressure value may be associated with normal blood flow—and thus oxygen delivery in a given patient at a certain point in time—while the same value might represent an abnormal blood pressure associated with decreased blood flow and abnormal oxygen delivery at another time, it is likely that a universally applicable normal blood pressure range does not exist for neonates even with the same gestational and postnatal age. Therefore only with appropriate monitoring of blood pressure, blood flow, and tissue oxygen delivery in each neonate can the normal blood pressure be defined for the individual patient and the given point in time. With this background information in mind, this chapter describes the information available on systemic and cerebral blood flow and oxygenation in relation to systemic blood pressure and the characteristic cerebral pathologies seen in the neonate, and the information focuses on the transitional period. By examining the pathologic processes in relation to blood pressure and flow, the chance of designing and providing timely and potentially effective treatment becomes more realistic. We also describe a paradigm for treatment of the pathologic processes underlying clinically evident brain injury in the preterm infant. However, it must be emphasized that only little evidence exists on the safety and effectiveness of the presently used approaches to treatment of neonatal hypotension.