title: Coupling of cerebral blood flow and oxygen consumption during hypothermia in newborn piglets as measured by time-resolved near-infrared spectroscopy: a pilot study.
abstract: Hypothermia (HT) is a potent neuroprotective therapy that is now widely used in following neurological emergencies, such as neonatal asphyxia. An important mechanism of HT-induced neuroprotection is attributed to the associated reduction in the cerebral metabolic rate of oxygen ([Formula: see text]). Since cerebral circulation and metabolism are tightly regulated, reduction in [Formula: see text] typically results in decreased cerebral blood flow (CBF); it is only under oxidative stress, e.g., hypoxia-ischemia, that oxygen extraction fraction (OEF) deviates from its basal value, which can lead to cerebral dysfunction. As such, it is critical to measure these key physiological parameters during therapeutic HT. This report investigates a noninvasive method of measuring the coupling of [Formula: see text] and CBF under HT and different anesthetic combinations of propofol/nitrous-oxide ([Formula: see text]) that may be used in clinical practice. Both CBF and [Formula: see text] decreased with decreasing temperature, but the OEF remained unchanged, which indicates a tight coupling of flow and metabolism under different anesthetics and over the mild HT temperature range (38°C to 33°C).
authors.affiliation: Lawson Health Research Institute, Imaging Program, 268 Grosvenor Street, London, Ontario N6A 4V2, Canada; Robarts Research Institute, Imaging Research Laboratories, 1151 Richmond Street North, London, Ontario N6A 5B7, Canada.
authors.forename: Mohammad Fazel
authors.initials: MF
authors.lastname: Bakhsheshi
authors.affiliation: Lawson Health Research Institute, Imaging Program, 268 Grosvenor Street, London, Ontario N6A 4V2, Canada; Western University, Department of Medical Biophysics, London, Ontario N6A 5C1, Canada.
authors.forename: Mamadou
authors.initials: M
authors.lastname: Diop
authors.affiliation: Lawson Health Research Institute , Imaging Program, 268 Grosvenor Street, London, Ontario N6A 4V2, Canada.
authors.forename: Laura B
authors.initials: LB
authors.lastname: Morrison
authors.affiliation: Lawson Health Research Institute, Imaging Program, 268 Grosvenor Street, London, Ontario N6A 4V2, Canada; Robarts Research Institute, Imaging Research Laboratories, 1151 Richmond Street North, London, Ontario N6A 5B7, Canada; Western University, Department of Medical Biophysics, London, Ontario N6A 5C1, Canada.
authors.forename: Keith
authors.initials: K
authors.lastname: St Lawrence
authors.affiliation: Lawson Health Research Institute, Imaging Program, 268 Grosvenor Street, London, Ontario N6A 4V2, Canada; Robarts Research Institute, Imaging Research Laboratories, 1151 Richmond Street North, London, Ontario N6A 5B7, Canada; Western University, Department of Medical Biophysics, London, Ontario N6A 5C1, Canada; Western University, Department of Medical Imaging, London, Ontario N6A 5W9, Canada.
authors.forename: Ting-Yim
authors.initials: TY
authors.lastname: Lee
keywords: brain temperature; cerebral blood flow; cerebral metabolic rate of oxygen; indocyanine green; oxygen extraction; time-resolved near-infrared
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