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

Martin M. Tisdall; Llias Tachtsidis; Terence S. Leung; Clare E. Elwell; Martin Smith

doi:10.1117/1.2718541

1 March 2007 Near-infrared spectroscopic quantification of changes in the concentration of oxidized cytochrome c oxidase in the healthy human brain during hypoxemia

Martin M. Tisdall, Llias Tachtsidis, Terence S. Leung, Clare E. Elwell, Martin Smith

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Journal of Biomedical Optics, Vol. 12, Issue 2, 024002 (March 2007). https://doi.org/10.1117/1.2718541

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.

©(2007) Society of Photo-Optical Instrumentation Engineers (SPIE)

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Martin M. Tisdall, Llias Tachtsidis, Terence S. Leung, Clare E. Elwell, and Martin Smith "Near-infrared spectroscopic quantification of changes in the concentration of oxidized cytochrome c oxidase in the healthy human brain during hypoxemia," Journal of Biomedical Optics 12(2), 024002 (1 March 2007). https://doi.org/10.1117/1.2718541

Published: 1 March 2007

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