Effectiveness of Near-Infrared Spectroscopy (NIRO-200NX, Pulse mode) for Risk Management in Carotid Artery Stenting

Abstract Background Near-infrared spectroscopy (NIRS) is an alternative monitoring method during carotid artery stenting (CAS). NIRS is reported to be effective in emergency care; however, it is unknown whether it can predict intraoperative ischemic intolerance and cerebral hyperperfusion during CAS. Objective Perioperative ischemic intolerance and cerebral hyperperfusion are potential events during CAS for carotid artery stenosis. We evaluated whether perioperative monitoring of the tissue oxygenation index (TOI) using NIRS (the NIRO system) can predict the occurrence of ischemic intolerance and cerebral hyperperfusion. Methods TOI of 27 patients was measured during CAS. The relationship between TOI and ischemic intolerance or cerebral hyperperfusion was analyzed, and the cut-off value of TOI was calculated to predict their occurrence. Results Ischemic intolerance occurred in five patients during balloon protection. TOI with ischemic intolerance was significantly lower than that without ischemic intolerance. The cut-off value of TOI to detect ischemic intolerance was 50%, and that of the TOI change rate before and after balloon protection was 80%. The ischemic symptoms in all cases recovered immediately after balloon deflation. Cerebral hyperperfusion phenomenon (CHP) was detected by single-photon emission computed tomography in four patients. These patients showed the transient rising of TOI immediately after CAS; however, none of these patients showed symptomatic CHP. The cut-off value of TOI to detect cerebral hyperperfusion was 109% compared to TOI before CAS. Conclusion The monitoring of TOI by the NIRO system is useful for detecting ischemic intolerance and cerebral hyperperfusion during CAS, and for preventing perioperative adverse events.