title: The Ontogeny of Cerebrovascular Critical Closing Pressure.
abstract: Premature infants are at risk of vascular neurological insults. Hypotension and hypertension are considered injurious, but neither condition is defined with consensus. Critical closing pressure (CrCP) is the arterial blood pressure (ABP) at which cerebral blood flow ceases. CrCP may serve to define subject-specific low or high ABP. Our objective was to quantify CrCP as a function of gestational age (GA). One hundred eighty-six premature infants with a GA range of 23-33 weeks, were monitored with umbilical artery catheters and transcranial Doppler insonation of middle cerebral artery flow velocity (FV) for 1-h sessions over the first week of life. CrCP was calculated using an impedance model derivation with Doppler-based estimations of cerebrovascular resistance and compliance. CrCP increased significantly with GA (r = 0.47; slope = 1.4 mmHg/week gestation), an association that persisted with multivariate analysis (p < 0.001). Higher diastolic ABP and higher GA were associated with increased CrCP (p <0.001 for both). CrCP increases significantly at the end of the second and beginning of the third trimester. The low CrCP observed in premature infants may explain their ability to tolerate low ABP without global cerebral infarct or hemorrhage.
authors.affiliation: Department of Pediatrics, Section of Neonatology, Texas Children's Hospital, Baylor College of Medicine, 6621 Fannin Street, W6-104, Houston, TX, USA. cjrhee@texaschildrens.org.
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Rhee
authors.affiliation: University of Texas at Houston School of Medicine, Houston, TX, USA.
authors.forename: Charles D
authors.initials: CD
authors.lastname: Fraser
authors.affiliation: Departments of Pediatrics and Anesthesiology, Texas Children's Hospital, Baylor College of Medicine, Houston, TX, USA.
authors.forename: Kathleen
authors.initials: K
authors.lastname: Kibler
authors.affiliation: Departments of Pediatrics and Anesthesiology, Texas Children's Hospital, Baylor College of Medicine, Houston, TX, USA.
authors.forename: Ronald B
authors.initials: RB
authors.lastname: Easley
authors.affiliation: Departments of Pediatrics and Anesthesiology, Texas Children's Hospital, Baylor College of Medicine, Houston, TX, USA.
authors.forename: Dean B
authors.initials: DB
authors.lastname: Andropoulos
authors.affiliation: Division of Neurosurgery, Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK.
authors.forename: Marek
authors.initials: M
authors.lastname: Czosnyka
authors.affiliation: Division of Neurosurgery, Addenbrooke's Hospital, Cambridge University, Cambridge, UK.
authors.forename: Georgios V
authors.initials: GV
authors.lastname: Varsos
authors.affiliation: Division of Neurosurgery, Addenbrooke's Hospital, Cambridge University, Cambridge, UK.
authors.forename: Peter
authors.initials: P
authors.lastname: Smielewski
authors.affiliation: Department of Cardiology, Texas Children's Hospital, Baylor College of Medicine, Houston, TX, USA.
authors.forename: Craig G
authors.initials: CG
authors.lastname: Rusin
authors.affiliation: Departments of Pediatrics and Anesthesiology, Texas Children's Hospital, Baylor College of Medicine, Houston, TX, USA.
authors.forename: Ken M
authors.initials: KM
authors.lastname: Brady
authors.affiliation: Departments of Pediatrics and Obstetrics and Gynecology, Section of Neonatology, Texas Children's Hospital, Baylor College of Medicine, Houston, TX, USA.
authors.forename: Jeffrey R
authors.initials: JR
authors.lastname: Kaiser
mesh_terms: D062186:Arterial Pressure / Q000502:physiology*; D001783:Blood Flow Velocity / Q000502:physiology*; D002560:Cerebrovascular Circulation / Q000502:physiology*; D003971:Diastole; D017097:Electric Impedance; D005260:Female; D005865:Gestational Age; D006801:Humans; D062071:Infant, Extremely Premature; D007231:Infant, Newborn; D007234:Infant, Premature; D007427:Intracranial Pressure / Q000502:physiology*; D008297:Male; D020768:Middle Cerebral Artery / Q000000981:diagnostic imaging* / Q000502:physiology; D008955:Models, Cardiovascular; D015999:Multivariate Analysis; D017585:Ultrasonography, Doppler, Transcranial; D014469:Umbilical Arteries / Q000502:physiology; D014655:Vascular Resistance
keywords: Arterial blood pressure; Closing margin; Critical closing pressure; Prematurity