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Journal of Biomedical Optics

Near-infrared spectroscopic quantification of changes in the concentration of oxidized cytochrome c oxidase in the healthy human brain during hypoxemia
Author(s): Martin M. Tisdall; Llias Tachtsidis; Terence S. Leung; Clare E. Elwell; Martin Smith
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Paper Abstract

The near-IR cytochrome c oxidase (CCO) signal has potential as a clinical marker of changes in mitochondrial oxygen utilization. We examine the CCO signal response to reduced oxygen delivery in the healthy human brain. We induced a reduction in arterial oxygen saturation from baseline levels to 80% in eight healthy adult humans, while minimizing changes in end tidal carbon dioxide tension. We measured changes in the cerebral concentrations of oxidized CCO (Δ[oxCCO]), oxyhemoglobin (Δ[HbO2]), and deoxyhemoglobin (Δ[HHb]) using broadband near-IR spectroscopy (NIRS), and estimated changes in cerebral oxygen delivery (ecDO2) using pulse oximetry and transcranial Doppler ultrasonography. Results are presented as median (interquartile range). At the nadir of hypoxemia ecDO2 decreased by 9.2 (5.4 to 12.1)% (p<0.0001), Δ[oxCCO] decreased by 0.24 (0.06 to 0.28) micromoles/l (p<0.01), total hemoglobin concentration increased by 2.83 (2.27 to 4.46) micromoles/l (p<0.0001), and change in hemoglobin difference concentration (Δ[Hbdiff]=Δ[HbO2]−Δ[HHb]) decreased by 12.72 (11.32 to 16.34) micromoles/l (p<0.0001). Change in ecDO2 correlated with Δ[oxCCO] (r=0.78, p<0.001), but not with either change in total hemoglobin concentration or Δ[Hbdiff]. This is the first description of cerebral Δ[oxCCO] during hypoxemia in healthy adults. Studies are ongoing to investigate the clinical relevance of this signal in patients with traumatic brain injury.

Paper Details

Date Published: 1 March 2007
PDF: 7 pages
J. Biomed. Opt. 12(2) 024002 doi: 10.1117/1.2718541
Published in: Journal of Biomedical Optics Volume 12, Issue 2
Show Author Affiliations
Martin M. Tisdall, National Hospital for Neurology & Neurosurgery (United Kingdom)
Llias Tachtsidis, Univ. College London (United Kingdom)
Terence S. Leung, Univ. College London (United Kingdom)
Clare E. Elwell, Univ. College London (United Kingdom)
Martin Smith, National Hospital for Neurology & Neurosurgery (United Kingdom)

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