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Assessment by Multi‐Distance Hyperspectral NIRS of Changes in the Oxidation State of Cytochrome C Oxidase (oxCCO) to Carotid Artery Compressions
Author(s) -
Shoemaker Leena,
Suwalski Marianne,
Milej Daniel,
Shoemaker J. K.,
Chui Jason,
St. Lawrence Keith
Publication year - 2022
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.2022.36.s1.r3459
Subject(s) - cytochrome c oxidase , cardiology , medicine , carotid endarterectomy , oxygenation , ischemia , chemistry , nuclear medicine , carotid arteries , mitochondrion , biochemistry
The occlusion of the common carotid artery (CCA) during carotid endarterectomy (CEA) is associated with a risk of cerebral ischemia due to inadequate collateral blood flow 1 . By monitoring tissue oxygen saturation (StO 2 ), near‐infrared spectroscopy (NIRS) is frequently employed during CEA 2 to determine sufficient oxygen delivery. However, StO 2 is only a proxy of oxygen metabolism and an unreliable marker of ischemic injury. In contrast, cytochrome c oxidase (oxCCO) is an enzyme in the mitochondrial electron transport chain and therefore a specific marker of aerobic metabolism 3 . Thus, the aim of this study was to assess the ability of a multi‐distance hyperspectral (hs) NIRS to monitor changes in StO 2 and oxCCO during CCA compressions in healthy participants. We hypothesized that changes in oxCCO concentration would be greater in the brain (i.e., long source‐detector distance, SDD) than in the extracerebral tissue (i.e., short SDD), and this difference would be larger than that of StO 2 . Methods We modified an in‐house built hsNIRS 4 to include a second channel for acquiring data at two SDD (1 and 3 cm) to detect potential changes in the extracerebral tissue. Data from 10 young, healthy participants was acquired continuously during one 30‐second unilateral digital CCA compression, performed ipsilateral to the location of the optic probes. In addition, cerebral blood flow index was determined using diffuse correlation spectroscopy and mean arterial blood pressure by finger photoplethysmography. Results During CCA compression, the change in oxCCO at 3 cm vs. 1 cm (0.4 ± 0.3 µM vs. 0.06 ± 0.1 µM, p = 0.027) was approximately 50% greater than the change in StO 2 at 3 cm vs. 1cm (‐4.0 ± 2.2% vs. 1.2 ± 0.7% p = 0.007). The corresponding decrease in cerebral blood flow was 57 ± 14% (p < 0.001 vs. baseline). Mean arterial blood pressure increased 4 ± 1 mmHg (p < 0.001 vs. baseline). Discussion A larger difference between the two distances was observed for oxCCO than StO 2 , likely due to the greater concentration of mitochondria in the brain compared to extracerebral tissues. Collecting multi‐distance hsNIRS demonstrated the enhanced sensitivity of oxCCO to the brain. Lastly, this study demonstrates the utility of momentary unilateral CCA compressions as a fast, easy, and strong perturbation for transiently altering cerebral inflow and metabolism. References (1) Aceto, Eur. J. Anestesiol.(2020); (2) Yu, Cochrane Database Syst. Rev.(2014); (3) Bale, J. Biomed. Opt. (2020); (4) Rajaram, Brain Sci (2020).