title: The Diastolic Closing Margin Is Associated with Intraventricular Hemorrhage in Premature Infants.
abstract: Premature infants are at an increased risk of intraventricular hemorrhage (IVH). The roles of hypotension and hyperemia are still debated. Critical closing pressure (CrCP) is the arterial blood pressure (ABP) at which cerebral blood flow (CBF) ceases. When diastolic ABP is equal to CrCP, CBF occurs only during systole. The difference between diastolic ABP and CrCP is the diastolic closing margin (DCM). We hypothesized that a low DCM was associated with IVH. One hundred eighty-six premature infants, with a gestational age (GA) range of 23-33 weeks, were monitored with umbilical artery catheters and transcranial Doppler insonation of middle cerebral artery flow velocity for 1-h sessions over the first week of life. CrCP was calculated linearly and using an impedance model. A multivariate generalized linear regression model was used to determine associations with severe IVH (grades 3-4). An elevated DCM by either method was associated with IVH (p < 0.0001 for the linear method; p < 0.001 for the impedance model). Lower 5-min Apgar scores, elevated mean CBF velocity, and lower mean ABP were also associated with IVH (p < 0.0001). Elevated DCM, not low DCM, was associated with severe IVH in this cohort.
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: Departments of Anesthesiology, Critical Care Medicine, and Pediatrics, Texas Children's Hospital/Baylor College of Medicine, Houston, TX, USA.
authors.forename: Kathleen K
authors.initials: KK
authors.lastname: Kibler
authors.affiliation: Departments of Anesthesiology, Critical Care Medicine, and Pediatrics, Texas Children's Hospital/Baylor College of Medicine, Houston, TX, USA.
authors.forename: R Blaine
authors.initials: RB
authors.lastname: Easley
authors.affiliation: Departments of Anesthesiology, Critical Care Medicine, and Pediatrics, 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, Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK.
authors.forename: Peter
authors.initials: P
authors.lastname: Smielewski
authors.affiliation: Department of Academic Neurosurgery, Addenbrooke's Hospital, University of Cambridge, Cambridge, UK.
authors.forename: Georgios V
authors.initials: GV
authors.lastname: Varsos
authors.affiliation: Departments of Anesthesiology, Critical Care Medicine, and Pediatrics, Texas Children's Hospital/Baylor College of Medicine, Houston, TX, USA.
authors.forename: Ken M
authors.initials: KM
authors.lastname: Brady
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: University of Texas at Houston School of Medicine, Houston, TX, USA.
authors.forename: Charles D
authors.initials: CD
authors.lastname: Fraser
authors.affiliation: Department of Biostatistics, University of Arkansas for Medical Sciences, Little Rock, AR, USA.
authors.forename: C Heath
authors.initials: CH
authors.lastname: Gauss
authors.affiliation: Department of Biostatistics, University of Arkansas for Medical Sciences, Little Rock, AR, USA.
authors.forename: D Keith
authors.initials: DK
authors.lastname: Williams
authors.affiliation: Department of Pediatrics, Section of Neonatology, Texas Children's Hospital/Baylor College of Medicine, 6621 Fannin Street, W6-104, Houston, TX, USA.
authors.forename: Jeffrey R
authors.initials: JR
authors.lastname: Kaiser
mesh_terms: D001034:Apgar Score; D062186:Arterial Pressure / Q000502:physiology*; D002543:Cerebral Hemorrhage / Q000453:epidemiology*; D002552:Cerebral Ventricles; D002560:Cerebrovascular Circulation / Q000502:physiology*; D003971:Diastole / Q000502:physiology*; D005260:Female; D006801:Humans; D062071:Infant, Extremely Premature; D007231:Infant, Newborn; D007234:Infant, Premature; D016014:Linear Models; D008297:Male; D020768:Middle Cerebral Artery / Q000000981:diagnostic imaging*; D008991:Monitoring, Physiologic; D015999:Multivariate Analysis; D016017:Odds Ratio; D012720:Severity of Illness Index; D017585:Ultrasonography, Doppler, Transcranial
keywords: Critical closing pressure; Diastolic closing margin; Hypertension; Hypotension; Intraventricular hemorrhage; Prematurity