2．脳血流モニターと運動誘発電位

Intraoperative Monitoring of Cerebral and Spinal Cord Perfusion in Thoracic and Thoracoabdominal Aortic Surgery

心臓血管外科領域における術中神経障害は，生命予後のみならず術後の生活の質（QOL）を著しく損なう重大な合併症の一つである．その主な原因の一つに，体外循環中の低灌流があげられる．特に弓部大動脈手術においては，弓部分枝（腕頭動脈，左総頸動脈，左鎖骨下動脈）の再建操作を伴うため，適切な脳保護を行わなければ低酸素性脳症を招く危険がある．

Neurological complications during thoracic and thoracoabdominal aortic surgery remain significant issues affecting both postoperative quality of life and long-term survival. Inadequate cerebral and spinal cord perfusion, as well as embolic events, are major contributors to such outcomes. Near-infrared spectroscopy （NIRS）-based regional cerebral oxygen saturation （rSO2） monitoring allows continuous, non-invasive assessment of cerebral perfusion and has become a routine adjunct in high-risk procedures. Factors such as mean arterial pressure, arterial carbon dioxide tension （PaCO2）, hemoglobin levels, and cardiac output all significantly influence rSO2 values. For spinal cord protection, motor evoked potential （MEP） monitoring provides a real-time assessment of the corticospinal tract integrity. Its utility is particularly prominent in thoracoabdominal aortic aneurysm repairs where spinal ischemia poses a risk of paraplegia. Prompt intraoperative responses―such as increasing blood pressure, cerebrospinal fluid drainage, or intercostal artery reconstruction―can be initiated based on MEP changes. At our institution, over 300 cases have been managed with MEP guidance, yielding favorable neurological outcomes. Integration of NIRS and MEP enables early detection of ischemia and timely interventions, thereby reducing neurological complications. Continued refinement and standardization of these modalities, in conjunction with other physiological and imaging assessments, are essential to further improve surgical outcomes.