Ide Kojiro
Hokusho University, School of Lifelong Sport, Northern Region Lifelong Sports Research Center, Hokkaido, Japan.
Neurophotonics. 2023 Oct;10(4):045002. doi: 10.1117/1.NPh.10.4.045002. Epub 2023 Oct 5.
Cerebrovascular reactivity can be evaluated by prefrontal cortex (PFC) hemodynamic responses and oxygenation changes secondary to hypoxia using near-infrared spectroscopy (NIRS). However, whether there are hemispheric differences in these NIRS-determined PFC hemodynamic responses and oxygenation changes remains unknown.
This study was performed to determine whether there are differences in the PFC hemodynamic responses and oxygenation changes secondary to hypoxia between the left and right frontal poles (FPL and FPR, respectively).
Fifteen young men participated in the study. During conduction of an isocapnic hypoxia protocol with a 10-min hypoxic phase at partial pressure of end-tidal oxygen () of 45 Torr, hemodynamic and oxygenation indices comprising oxygenated hemoglobin (oxy-Hb), deoxygenated Hb (deoxy-Hb), total Hb (total-Hb), and tissue oxygen saturation () over FPL and FPR were measured by NIRS. The heart rate (HR) was evaluated by electrocardiography.
In response to hypoxia, the HR increased, oxy-Hb decreased, deoxy-Hb increased, total-Hb increased above baseline, and decreased. There was no difference in the change in total-Hb between FPL and FPR. However, there were greater changes in oxy-Hb, deoxy-Hb, and over FPL than over FPR, indicating that PFC oxygenation asymmetry occurs in response to hypoxia. Moreover, the change in total-Hb over FPL was associated with the increase in HR.
NIRS-determined hemodynamic responses and oxygenation changes secondary to hypoxia might not simply reflect the direct effect of hypoxia on cerebral vessels. Although there is no hemispheric difference in the PFC hemodynamic responses to hypoxia as in total-Hb, PFC oxygenation asymmetry occurs in young adults.
脑血管反应性可通过前额叶皮质（PFC）血流动力学反应以及利用近红外光谱（NIRS）对缺氧继发的氧合变化进行评估。然而，这些由NIRS测定的PFC血流动力学反应和氧合变化是否存在半球差异仍不清楚。
本研究旨在确定左、右额极（分别为FPL和FPR）在缺氧继发的PFC血流动力学反应和氧合变化方面是否存在差异。
15名年轻男性参与了本研究。在进行等容性缺氧方案时，在呼气末氧分压（）为45 Torr的情况下进行10分钟的缺氧阶段，通过NIRS测量FPL和FPR上的血流动力学和氧合指标，包括氧合血红蛋白（oxy-Hb）、脱氧血红蛋白（deoxy-Hb）、总血红蛋白（total-Hb）和组织氧饱和度（）。通过心电图评估心率（HR）。
对缺氧的反应中，HR升高，oxy-Hb降低，deoxy-Hb升高，total-Hb高于基线水平升高，而降低。FPL和FPR之间total-Hb的变化没有差异。然而，FPL上的oxy-Hb、deoxy-Hb和的变化比FPR上的变化更大，表明PFC氧合不对称是对缺氧的反应。此外，FPL上total-Hb的变化与HR的增加相关。
NIRS测定的缺氧继发的血流动力学反应和氧合变化可能并不简单地反映缺氧对脑血管的直接影响。尽管在PFC对缺氧的血流动力学反应中，如total-Hb那样不存在半球差异，但在年轻成年人中会出现PFC氧合不对称。
