Canadian journal of anaesthesia = Journal canadien d'anesthésie
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Clinically available near-infrared spectroscopy (NIRS) devices use two to five wavelengths of light to measure the relative amounts of oxyhemoglobin and deoxyhemoglobin in tissue to determine tissue hemoglobin oxygen saturation (StO2). In addition to StO2, broadband NIRS devices (using hundreds of wavelengths of light) may be able to measure the oxidation state of mitochondrial cytochrome aa3 (Cytox) which reflects the subcellular energetic state. We hypothesize that broadband NIRS devices can measure Cytox independent of changes in hemoglobin saturation. ⋯ Broadband NIRS can effectively measure the directionality of changes in both Cytox and StO2 by uncoupling the cytochrome and hemoglobin signals through inhibition of the electron transport chain and anoxia.