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Research Papers

Near-infrared spectroscopic quantification of changes in the concentration of oxidized cytochrome c oxidase in the healthy human brain during hypoxemia

[+] Author Affiliations
Martin M. Tisdall

The National Hospital for Neurology and Neurosurgery, Department of Neuroanaesthesia and Neurocritical Care, Queen Square, London WC1N 3BG, United Kingdom

Ilias Tachtsidis, Terence S. Leung, Clare E. Elwell

Department of Medical Physics and Bioengineering, University College London, Gower Street, London WC1E 6BT, United Kingdom

Martin Smith

The National Hospital for Neurology and Neurosurgery, Department of Neuroanaesthesia and Neurocritical Care, Queen Square, London WC1N 3BG, United Kingdom

J. Biomed. Opt. 12(2), 024002 (March 30, 2007). doi:10.1117/1.2718541
History: Received August 24, 2006; Revised December 05, 2006; Accepted December 06, 2006; Published March 30, 2007
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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.

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© 2007 Society of Photo-Optical Instrumentation Engineers

Citation

Martin M. Tisdall ; Ilias Tachtsidis ; Martin Smith ; Terence S. Leung and Clare E. Elwell
"Near-infrared spectroscopic quantification of changes in the concentration of oxidized cytochrome c oxidase in the healthy human brain during hypoxemia", J. Biomed. Opt. 12(2), 024002 (March 30, 2007). ; http://dx.doi.org/10.1117/1.2718541


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