Feasibility of intraoperative resting-state functional near-infrared spectroscopy for assessing the effects of propofol anesthesia on frontal cortical activity and network organization

The neurological mechanisms of general anesthesia have been studied extensively using electroencephalography (EEG) and functional magnetic resonance imaging (fMRI). The current study evaluated the feasibility of using functional near-infrared spectroscopy (fNIRS) to evaluate the effects of propofol-based general anesthesia on frontal cortical activity and functional connectivity (FC) during surgery. Seventy-eight patients scheduled for elective colorectal cancer resection were recruited. Frontal fNIRS signals were recorded before anesthesia and during stable anesthesia following resection. Analyses focused on changes in fractional amplitude of low-frequency fluctuations (fALFF), resting-state (rs) FC, and graph theory network metrics. Significant reductions in frontal fALFF, rsFC, and Eg (global efficiency of the frontal network) were detected during anesthesia, particularly among components of the executive control and dorsal attention networks. Characteristic path length (Lp) was longer during anesthesia. The small-world metrics sigma and gamma were also weaker during anesthesia, but network small-world properties (σ > 1) were preserved. Functional near-infrared spectroscopy can detect hemodynamic correlates of anesthesia-associated changes in cortical activity and network organization, providing indirect signatures of altered cortical states and providing evidence for the future development of complementary intraoperative monitoring approaches and investigation of anesthesia-related cortical mechanisms. Chinese Clinical Trial Registry, identifier: ChiCTR2200063584, Date: 12/9/2022.