Pham Thao, Fernandez Cristianne, Blaney Giles, Tgavalekos Kristen, Sassaroli Angelo, Cai Xuemei, Bibu Steve, Kornbluth Joshua, Fantini Sergio
Department of Biomedical Engineering, Tufts University, Medford, MA, United States.
Department of Neurology, Tufts University School of Medicine, Boston, MA, United States.
Front Neurol. 2021 Nov 16;12:745987. doi: 10.3389/fneur.2021.745987. eCollection 2021.
Cerebral autoregulation limits the variability of cerebral blood flow (CBF) in the presence of systemic arterial blood pressure (ABP) changes. Monitoring cerebral autoregulation is important in the Neurocritical Care Unit (NCCU) to assess cerebral health. Here, our goal is to identify optimal frequency-domain near-infrared spectroscopy (FD-NIRS) parameters and apply a hemodynamic model of coherent hemodynamics spectroscopy (CHS) to assess cerebral autoregulation in healthy adult subjects and NCCU patients. In five healthy subjects and three NCCU patients, ABP oscillations at a frequency around 0.065 Hz were induced by cyclic inflation-deflation of pneumatic thigh cuffs. Transfer function analysis based on wavelet transform was performed to measure dynamic relationships between ABP and oscillations in oxy- (), deoxy- (), and total- () hemoglobin concentrations measured with different FD-NIRS methods. In healthy subjects, we also obtained the dynamic CBF-ABP relationship by using FD-NIRS measurements and the CHS model. In healthy subjects, an interval of hypercapnia was performed to induce cerebral autoregulation impairment. In NCCU patients, the optical measurements of autoregulation were linked to individual clinical diagnoses. In healthy subjects, hypercapnia leads to a more negative phase difference of both and oscillations vs. ABP oscillations, which are consistent across different FD-NIRS methods and are highly correlated with a more negative phase difference CBF vs. ABP. In the NCCU, a less negative phase difference of vs. ABP was observed in one patient as compared to two others, indicating a better autoregulation in that patient. Non-invasive optical measurements of induced phase difference between and ABP show the strongest sensitivity to cerebral autoregulation. The results from healthy subjects also show that the CHS model, in combination with FD-NIRS, can be applied to measure the CBF-ABP dynamics for a better direct measurement of cerebral autoregulation.
在体循环动脉血压（ABP）发生变化时，脑自动调节可限制脑血流量（CBF）的变异性。在神经重症监护病房（NCCU）中，监测脑自动调节对于评估脑部健康状况至关重要。在此，我们的目标是确定最佳频域近红外光谱（FD-NIRS）参数，并应用相干血流动力学光谱（CHS）的血流动力学模型来评估健康成年受试者和NCCU患者的脑自动调节。在5名健康受试者和3名NCCU患者中，通过气动大腿袖带的周期性充气-放气来诱发频率约为0.065 Hz的ABP振荡。基于小波变换进行传递函数分析，以测量ABP与采用不同FD-NIRS方法测得的氧合血红蛋白（）、脱氧血红蛋白（）和总血红蛋白（）浓度振荡之间的动态关系。在健康受试者中，我们还通过使用FD-NIRS测量和CHS模型获得了动态CBF-ABP关系。在健康受试者中，进行了一段高碳酸血症期以诱发脑自动调节功能受损。在NCCU患者中，自动调节的光学测量结果与个体临床诊断相关联。在健康受试者中，高碳酸血症导致与ABP振荡相比，和振荡的相位差更负，这在不同的FD-NIRS方法中是一致的，并且与CBF与ABP之间更负的相位差高度相关。在NCCU中，与另外两名患者相比，一名患者的与ABP之间的相位差负性较小，表明该患者的自动调节功能较好。对与ABP之间诱发的相位差进行无创光学测量对脑自动调节显示出最强的敏感性。健康受试者的结果还表明，CHS模型与FD-NIRS相结合，可用于测量CBF-ABP动态变化，以便更好地直接测量脑自动调节。
