title: A novel method for assessing cerebral autoregulation in preterm infants using transfer function analysis.
abstract: BACKGROUND
  Autoregulatory dysfunction is an important contributor to brain injury in premature infants, particularly intraventricular hemorrhage (IVH). The autoregulatory system acts as a filter that dampens the systemic blood flow to follow a normal cerebral perfusion profile.
  
  
  METHODS
  Simultaneous arterial blood pressure and cerebral near-infrared spectroscopy (NIRS) data were collected from infants born before 28 wk estimated gestational age. The resulting data were preprocessed and then divided into nonoverlapping 20-min epochs. The transfer function estimate was calculated to determine dampening ability.
  
  
  RESULTS
  Sixty-two infants were prospectively recruited with a mean estimated gestational age of 25.4 ± 1.3 wk and birth weight of 832 ± 199 g. 67% were male, 24/62 had IVH, 17/62 received dopamine, 47/62 had antenatal steroid exposure, and 22/62 received fentanyl.Advancing estimated gestational age and birth weight z-score predicted stronger dampening while African-American race and IVH of any grade predicted weaker dampening.
  
  
  CONCLUSIONS
  This preliminary report suggests an impairment in dampening ability associated with immaturity, decreased birth weight z-score, and African-American race. Decreased dampening is also associated with IVH, although these results cannot distinguish between decreased dampening as an antecedent or sequela of IVH. These observations should be studied in a larger sample.
authors.affiliation: Division of Newborn Medicine, Edward Mallinckrodt Department of Pediatrics, Washington University School of Medicine, St. Louis, Missouri.
authors.forename: Zachary A
authors.initials: ZA
authors.lastname: Vesoulis
authors.affiliation: Division of Newborn Medicine, Edward Mallinckrodt Department of Pediatrics, Washington University School of Medicine, St. Louis, Missouri.
authors.forename: Steve M
authors.initials: SM
authors.lastname: Liao
authors.affiliation: Division of Newborn Medicine, Edward Mallinckrodt Department of Pediatrics, Washington University School of Medicine, St. Louis, Missouri.
authors.forename: Shamik B
authors.initials: SB
authors.lastname: Trivedi
authors.affiliation: Division of Newborn Medicine, Edward Mallinckrodt Department of Pediatrics, Washington University School of Medicine, St. Louis, Missouri.
authors.forename: Nathalie El
authors.initials: NE
authors.lastname: Ters
authors.affiliation: Division of Newborn Medicine, Edward Mallinckrodt Department of Pediatrics, Washington University School of Medicine, St. Louis, Missouri.
authors.forename: Amit M
authors.initials: AM
authors.lastname: Mathur
mesh_terms: D001724:Birth Weight; D001783:Blood Flow Velocity; D001794:Blood Pressure; D002543:Cerebral Hemorrhage / Q000000981:diagnostic imaging / Q000503:physiopathology*; D002560:Cerebrovascular Circulation; D005260:Female; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature; D007235:Infant, Premature, Diseases / Q000000981:diagnostic imaging / Q000503:physiopathology; D008297:Male; D011446:Prospective Studies; D012044:Regression Analysis; D012815:Signal Processing, Computer-Assisted; D019265:Spectroscopy, Near-Infrared