Payne S J, Mohammad J, Tisdall M M, Tachtsidis I
Biomed Opt Express. 2011 Mar 25;2(4):966-79. doi: 10.1364/BOE.2.000979.
Near Infra-Red Spectroscopy (NIRS) is a non-invasive technique which can be used to investigate cerebral haemodynamics and oxygenation with high temporal resolution. When combined with measures of Cerebral Blood Flow (CBF), it has the potential to provide information about oxygen delivery, utilization and metabolism. However, the interpretation of experimental results is complex. Measured NIRS signals reflect both scalp and cerebral haemodynamics and are influenced by many factors. The relationship between Arterial Blood Pressure (ABP) and CBF has been widely investigated and it central to cerebral autoregulation. Changes in arterial blood gas levels have a significant effect on ABP and CBF and these relationships have been quantified previously. The relationship between ABP and NIRS signals, however, has not been fully characterized. In this paper, we thus investigate the influence of changes in arterial blood gas levels both experimentally and theoretically, using an extended mathematical model of cerebral blood flow and metabolism, in terms of the phase angle at 0.1 Hz. The autoregulation response is found to be strongly dependent upon the carbon dioxide (CO2) partial pressure but much less so upon changes in arterial oxygen saturation (SaO2). The results for phase angle sensitivity to CO2 show good agreement between experimental and theory, but a poorer agreement is found for the sensitivity to SaO2.
近红外光谱（NIRS）是一种非侵入性技术，可用于以高时间分辨率研究脑血流动力学和氧合作用。当与脑血流量（CBF）测量相结合时，它有潜力提供有关氧输送、利用和代谢的信息。然而，实验结果的解释很复杂。测量的NIRS信号反映头皮和脑血流动力学，并且受许多因素影响。动脉血压（ABP）与CBF之间的关系已得到广泛研究，并且是脑自动调节的核心。动脉血气水平的变化对ABP和CBF有显著影响，并且这些关系先前已被量化。然而，ABP与NIRS信号之间的关系尚未得到充分表征。因此，在本文中，我们使用扩展的脑血流和代谢数学模型，从0.1Hz的相角方面，通过实验和理论研究动脉血气水平变化的影响。发现自动调节反应强烈依赖于二氧化碳（CO2）分压，但对动脉血氧饱和度（SaO2）变化的依赖性要小得多。相角对CO2的敏感性结果在实验和理论之间显示出良好的一致性，但对SaO2的敏感性一致性较差。
