title: Ontogeny of cerebrovascular critical closing pressure.
abstract: BACKGROUND
  Premature infants are at risk of vascular neurologic insults. Hypotension and hypertension are considered injurious, but neither condition is defined with consensus. Cerebrovascular critical closing pressure (CrCP) is the arterial blood pressure (ABP) at which cerebral blood flow (CBF) ceases. CrCP may serve to define subject-specific low or high ABP. Our objective was to determine the ontogeny of CrCP.
  
  
  METHODS
  Premature infants (n = 179) with gestational age (GA) from 23-31 wk had recordings of ABP and middle cerebral artery flow velocity twice daily for 3 d and then daily for the duration of the first week of life. All infants received mechanical ventilation. CrCP was calculated using an impedance-model derivation with Doppler-based estimations of cerebrovascular resistance and compliance. The association between GA and CrCP was determined in a multivariate analysis.
  
  
  RESULTS
  The median (interquartile range) CrCP for the cohort was 22 mm Hg (19-25 mm Hg). CrCP increased significantly with GA (r = 0.6; slope = 1.4 mm Hg/wk gestation), an association that persisted with multivariate analysis (P < 0.0001).
  
  
  CONCLUSIONS
  CrCP increased significantly from 23 to 31 wk gestation. The low CrCP observed in very premature infants may explain their ability to tolerate low ABP without global cerebral infarct or hemorrhage.
authors.affiliation: Department of Pediatrics, Baylor College of Medicine, Houston, Texas.
authors.forename: Christopher J
authors.identifier: 000000026478564X
authors.initials: CJ
authors.lastname: Rhee
authors.affiliation: University of Texas at Houston School of Medicine, Houston, Texas.
authors.forename: Charles D
authors.initials: CD
authors.lastname: Fraser
authors.affiliation: 1] Department of Pediatrics, Baylor College of Medicine, Houston, Texas [2] Department of Anesthesiology, Baylor College of Medicine, Houston, Texas.
authors.forename: Kathleen
authors.initials: K
authors.lastname: Kibler
authors.affiliation: 1] Department of Pediatrics, Baylor College of Medicine, Houston, Texas [2] Department of Anesthesiology, Baylor College of Medicine, Houston, Texas.
authors.forename: Ronald B
authors.initials: RB
authors.lastname: Easley
authors.affiliation: 1] Department of Pediatrics, Baylor College of Medicine, Houston, Texas [2] Department of Anesthesiology, Baylor College of Medicine, Houston, Texas.
authors.forename: Dean B
authors.initials: DB
authors.lastname: Andropoulos
authors.affiliation: Division of Neurosurgery, Cambridge University, Cambridge, England, UK.
authors.forename: Marek
authors.initials: M
authors.lastname: Czosnyka
authors.affiliation: Division of Neurosurgery, Cambridge University, Cambridge, England, UK.
authors.forename: Georgios V
authors.initials: GV
authors.lastname: Varsos
authors.affiliation: Division of Neurosurgery, Cambridge University, Cambridge, England, UK.
authors.forename: Peter
authors.initials: P
authors.lastname: Smielewski
authors.affiliation: Department of Cardiology, Baylor College of Medicine, Houston, Texas.
authors.forename: Craig G
authors.initials: CG
authors.lastname: Rusin
authors.affiliation: 1] Department of Pediatrics, Baylor College of Medicine, Houston, Texas [2] Department of Anesthesiology, Baylor College of Medicine, Houston, Texas.
authors.forename: Ken M
authors.initials: KM
authors.lastname: Brady
authors.affiliation: 1] Department of Pediatrics, Baylor College of Medicine, Houston, Texas [2] Department Obstetrics and Gynecology, Baylor College of Medicine, Houston, Texas.
authors.forename: Jeffrey R
authors.initials: JR
authors.lastname: Kaiser
mesh_terms: D062186:Arterial Pressure; D001783:Blood Flow Velocity / Q000502:physiology*; D001794:Blood Pressure / Q000502:physiology; D002560:Cerebrovascular Circulation / Q000502:physiology*; D005260:Female; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature; D008297:Male; D020768:Middle Cerebral Artery; D008991:Monitoring, Physiologic; D015999:Multivariate Analysis; D011446:Prospective Studies; D012121:Respiration, Artificial; D017585:Ultrasonography, Doppler, Transcranial; D014655:Vascular Resistance / Q000502:physiology
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