Cerebral Hemodynamics in Premature Infants.

Rhee,  Christopher J; Rios,  Danielle R; Kaiser,  Jeffrey R; Brady,  Ken

doi:2018.25.1.1

Neonatal Med > Volume 25(1); 2018 > Article

Review

Neonatal Medicine 2018;25(1):1-6.
DOI: https://doi.org/10.5385/nm.2018.25.1.1 Published online February 28, 2018.

Cerebral Hemodynamics in Premature Infants.

Christopher J Rhee, Danielle R Rios, Jeffrey R Kaiser, Ken Brady

¹Section of Neonatology, Department of Pediatrics, Texas Children's Hospital, Baylor College of Medicine, Houston, TX, United States. cjrhee@texaschildrens.org
²Department of Pediatrics, Obstetrics and Gynecology, Hershey Medical Center, Penn State College of Medicine, Milton S, Hershey, PA, United States.
³Section of Neonatology, Department of Pediatrics, Critical Care Medicine and Anesthesiology, Texas Children's Hospital, Baylor College of Medicine, Houston, TX, United States.

Abstract

Extremely low birth weight infants remain at increased risk of intraventricular hemorrhage from the fragile vascular bed of the germinal matrix; the roles of hypotension (ischemia) and reperfusion (hyperemia) in the development of intraventricular hemorrhage are still debated. Cerebrovascular pressure autoregulation protects the brain by maintaining constant cerebral blood flow despite changes in blood pressure. The ontogeny of cerebrovascular pressure autoregulation has not been well established and uncertainty remains about the optimal arterial blood pressure required to support brain perfusion. Another important aspect of premature cerebral hemodynamics is the critical closing pressure––the arterial blood pressure at which cerebral blood flow ceases. Interestingly, in premature infants, the critical closing pressure approximates the mean arterial blood pressure. Often in this unique population, cerebral blood flow occurs only during systole when the diastolic arterial blood pressure is equal to the critical closing pressure. Moreover, the diastolic closing margin, a metric of cerebral perfusion that normalizes diastolic arterial blood pressure to the critical closing pressure, may be a better measure than arterial blood pressure for defining cerebral perfusion in premature infants. Elevated diastolic closing margin has been associated with intraventricular hemorrhage. This review summarizes the current state of understanding of cerebral hemodynamics in premature infants.

Key Words: Premature; Intraventricular hemorrhage; Cerebral autoregulation; Critical closing pressure; Diastolic closing margin