title: Early postoperative changes in cerebral oxygen metabolism following neonatal cardiac surgery: effects of surgical duration.
abstract: OBJECTIVE
  The early postoperative period following neonatal cardiac surgery is a time of increased risk for brain injury, yet the mechanisms underlying this risk are unknown. To understand these risks more completely, we quantified changes in postoperative cerebral metabolic rate of oxygen (CMRO(2)), oxygen extraction fraction (OEF), and cerebral blood flow (CBF) compared with preoperative levels by using noninvasive optical modalities.
  
  
  METHODS
  Diffuse optical spectroscopy and diffuse correlation spectroscopy were used concurrently to derive cerebral blood flow and oxygen utilization postoperatively for 12 hours. Relative changes in CMRO(2), OEF, and CBF were quantified with reference to preoperative data. A mixed-effect model was used to investigate the influence of total support time and deep hypothermic circulatory arrest duration on relative changes in CMRO(2), OEF, and CBF.
  
  
  RESULTS
  Relative changes in CMRO(2), OEF, and CBF were assessed in 36 patients, 21 with single-ventricle defects and 15 with 2-ventricle defects. Among patients with single-ventricle lesions, deep hypothermic circulatory arrest duration did not affect relative changes in CMRO(2), CBF, or OEF (P > .05). Among 2-ventricle patients, total support time was not a significant predictor of relative changes in CMRO(2) or CBF (P > .05), although longer total support time was associated significantly with greater increases in relative change of postoperative OEF (P = .008).
  
  
  CONCLUSIONS
  Noninvasive diffuse optical techniques were used to quantify postoperative relative changes in CMRO(2), CBF, and OEF for the first time in this observational pilot study. Pilot data suggest that surgical duration does not account for observed variability in the relative change in CMRO(2), and that more comprehensive clinical studies using the new technology are feasible and warranted to elucidate these issues further.
authors.affiliation: Division of Neurology, The Children's Hospital of Philadelphia, Philadelphia, PA, USA. buckley@nmr.mgh.harvard.edu
authors.forename: Erin M
authors.initials: EM
authors.lastname: Buckley
authors.forename: Jennifer M
authors.initials: JM
authors.lastname: Lynch
authors.forename: Donna A
authors.initials: DA
authors.lastname: Goff
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Schwab
authors.forename: Wesley B
authors.initials: WB
authors.lastname: Baker
authors.forename: Turgut
authors.initials: T
authors.lastname: Durduran
authors.forename: David R
authors.initials: DR
authors.lastname: Busch
authors.forename: Susan C
authors.initials: SC
authors.lastname: Nicolson
authors.forename: Lisa M
authors.initials: LM
authors.lastname: Montenegro
authors.forename: Maryam Y
authors.initials: MY
authors.lastname: Naim
authors.forename: Rui
authors.initials: R
authors.lastname: Xiao
authors.forename: Thomas L
authors.initials: TL
authors.lastname: Spray
authors.forename: A G
authors.initials: AG
authors.lastname: Yodh
authors.forename: J William
authors.initials: JW
authors.lastname: Gaynor
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Licht
mesh_terms: D001783:Blood Flow Velocity; D001921:Brain / Q000098:blood supply* / Q000378:metabolism*; D006348:Cardiac Surgical Procedures / Q000009:adverse effects; D002560:Cerebrovascular Circulation; D050792:Circulatory Arrest, Deep Hypothermia Induced; D005260:Female; D006330:Heart Defects, Congenital / Q000097:blood / Q000601:surgery*; D006801:Humans; D007223:Infant; D008297:Male; D010100:Oxygen / Q000097:blood*; D010101:Oxygen Consumption; D010865:Pilot Projects; D011446:Prospective Studies; D012039:Regional Blood Flow; D019265:Spectroscopy, Near-Infrared; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D010100:Oxygen